Dina H El-Ghonemy | National Research Centre (original) (raw)

Papers by Dina H El-Ghonemy

Research paper thumbnail of Immobilization and characterization of a thermostable beta-glucosidase from Aspergillus terreus NRRL 265

The Journal of Microbiology, Biotechnology and Food Sciences, Feb 1, 2015

Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment ... more Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment in calcium-alginate beads. The activity of the free and immobilized enzymes as a function of pH, temperature, and periodic use were compared. Whey permeate, a byproduct of cheese industry, was served as an inexpensive medium, which made the process economical and reduced the cost of enzyme production and also reduced the environmental pollution. The results indicated that, the immobilized β-glucosidase was retained about 73 % of the original activity exhibited by the free enzyme. The optimum temperature for the enzyme activity was improved by 5ºC after immobilization. Immobilized β-glucosidase was exhibited great thermal stability, whereas, at 70ºC, the free enzyme lost its activity after 30 min of incubation, while the immobilized enzyme showed more stability in comparison to the free form as it retained about 13.4 % of its initial activity under the same conditions. Moreover, the pH stability was improved following immobilization, whereas, the immobilized enzyme was stable in pH ranging from 4.0 to 7.0 with no change in activity, while its stability slightly decreases for more alkaline or acidic conditions (retaining 82.4 % and 67.4 % of the initial activity at pH 8.0 and 3.5, after 1 h of incubation). The results also indicated the possibility of reusing Ca alginate-immobilized β-glucosidase in industrial applications for 10 cycles with 53.7 % retained activity. ARTICLE INFO

Research paper thumbnail of Extracellular β-d-fructofuranosidase from a novel Aspergillus sp. DHE1 with high potential for biotechnological applications: Purification and biochemical characterization

Biocatalysis and agricultural biotechnology, Mar 1, 2023

Research paper thumbnail of Extracellular Glutaminase-Free L-Asparaginase from Trichoderma Viride F2: Purification, Biochemical Characterization and Evaluation of Its Potential in Mitigating Acrylamide Formation in Starchy Fried Food

The Journal of Microbiology, Biotechnology and Food Sciences, Oct 1, 2021

Research paper thumbnail of Screening Studies on the Formation of Β-Glucosidase from Some Filamentous Fungi

Advances in food sciences, 2009

ABSTRACT Twenty-five strains of different filamentous fungi were screened for their abilities to ... more ABSTRACT Twenty-five strains of different filamentous fungi were screened for their abilities to produce intracellular β-glucosidase using modified D-cellobiose Czapek Doxs liquid medium. The results revealed that nearly all fungi under study (23 out of 25) produced β-glucosidase in different proportions. Aspergillus terreus NRRL 265, A. phoenicis NRRL 365, Penicillium martensii NRC 345, P. purpurescens NRC 846 and P. cyclopium NRC 881, producing considerable amounts of enzyme as compared to the other cultures, were selected for β-glucosidase quantitative assay. Among them, Aspergillus terreus NRRL 265 was found to produce high levels of an intracellular β-glucosidase besides the other two components of cellulase system, namely exo-(1,4)-β-D-glucanase ( FPase, EC 3.2.1.91 ) and endo-(1,4)-β-D-glucanase (carboxymethyl cellulase (CMCase), EC 3.2.1.4).

Research paper thumbnail of Optimization of Culture Conditions for the Highest Lipid Production from some Oleaginous Fungi for Biodiesel Preparation

Asian Journal of Applied Sciences, Oct 15, 2014

Ten different filamentous fungi were screened for their abilities to produce lipid. An oleaginous... more Ten different filamentous fungi were screened for their abilities to produce lipid. An oleaginous fungus strain Trichoderma viride NRC 314 was found to be the highest lipid producer (>20%) among the tested filamentous fungi. Optimization of culture conditions for maximum lipid production was investigated, and the results reported clearly indicated that, the potato dextrose (PD) liquid medium, at a concentration of 50 g/l for dextrose, was the most suitable medium for lipid production with initial pH 5.0, incubation temperature 28°C, after five days of incubation in a static condition. In addition, neither yeast extract nor sugar cane molasses supplement exhibits any significant effects on lipid accumulation. The GC/Ms analysis indicated that, the n-hexane lipid fraction of T. viride 314 was mainly composed of 30.01% Palmitoleic acid (C16:1), 23% Linoleic Acid (C18:2), 13% Linolenic acid (C18:3) and about 8% Erucic acid (C22:1). Furthermore, the total saturated fatty acids represented 8.3%, while that of the unsaturated was 81.74%. Therefore, our study suggests that, SCOs of oleaginous fungi could be used as a potential feedstock for biodiesel production with Trichoderma viride NRC 314 as a promising candidate.

Research paper thumbnail of Effective bioconversion of feather-waste Keratin by Thermo-Surfactant Stable Alkaline Keratinase produced from Aspergillus sp. DHE7 with promising biotechnological application in detergent formulations

Biocatalysis and agricultural biotechnology, Aug 1, 2021

Abstract Keratin-rich wastes are troublesome pollutants that their accumulation could lead to env... more Abstract Keratin-rich wastes are troublesome pollutants that their accumulation could lead to environmental problems. Microbial degradation of keratin wastes has emerged as an alternative bio-catalyst to steam-pressure cooking and alkali hydrolysis for the recycling of such residues to value-added products. The current work investigates the purification and biochemical characterisation of an extracellular keratinase from new Aspergillus sp. DHE7 using turkey feathers as substrate. The enzyme was purified 31-fold with a final yield of 37.5%. Purified keratinase is monomeric and its molecular mass was estimated to be 33 kDa as demonstrated on SDS-PAGE. The enzyme was active in wide range of pH (7.0–11) and temperature (37–70 °C) profiles with maximum activity at pH 8.5 and 60 °C. The activity was strongly suppressed by phenylmethylsulfonyl fluoride (93.4% inhibition) and moderately inhibited by EDTA (41.2% inhibition), suggesting that the current keratinase belongs to serine-metalloprotease. Bivalent cations, such as Ca2+, Zn2+, and Mn2+, enhanced enzyme activity by 165.7%, 176.3%, and 194.8%, respectively. The purified keratinase exhibited a wide proteolytic activity towards soluble and insoluble protein substrates displaying its greater activity toward casein, keratin, bovine serum albumin, and gelatin, followed by feathers, goat hair, and wool, and was substantially stable and compliant with surfactants and commercial laundry detergents. The Km, Vmax, Kcat and Kcat/Km values on keratin were 2.2 mg/mL, 2702.7 U/mL, 136.5 s−1 and 62.04 (s−1/mg mL−1), respectively. According to these characteristics, Aspergillus sp. DHE7 keratinase is suggested as a potential candidate for use in detergent formulations (as an additive) and in various biotechnological applications.

Research paper thumbnail of Extracellular Alkaline Lipase from a Novel Fungus Curvularia sp. DHE 5: Optimization of Physicochemical Parameters, Partial Purification and Characterization

Food Technology and Biotechnology, 2017

Thirty isolated fungal strains were screened for lipase production using Phenol Red plates, conta... more Thirty isolated fungal strains were screened for lipase production using Phenol Red plates, containing tributyrin as lipidic substrate, and a novel fungus identified genetically as Curvularia sp. DHE 5 was found as the most prominent strain. Various agro-industrial substrates were evaluated as inert supports for lipase production in solid-state fermentation. The highest yield of lipase ((83.4±2.2) U/g on dry mass basis) was reported with wheat bran medium after seven days of fermentation at pH=7.0, temperature of 30 °C, 70 % moisture content, inoculum size of 1.27•10 7 spore/mL and 2 % olive oil as an inducer. Supplementation of the medium with 0.05 % KCl as an ion source further increased lipase production to (88.9±1.2) U/g on dry mass basis. The enzyme was partially purified through ammonium sulphate fractionation (40 %) followed by dialysis, and its optimum pH and temperature were reported at 8.0 and 50 °C, respectively, with remarkable pH and thermal stability.

Research paper thumbnail of Production and purification of bioactive compounds with potent antimicrobial activity from a novel terrestrial fungus Aspergillus sp. DHE 4

Biocatalysis and agricultural biotechnology, Sep 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Purification and characterization of the enzymes involved in nicotinamide adenine dinucleotide degradation by Penicillium brevicompactum NRC 829

3 biotech, Jan 21, 2016

The present study was conducted to investigate a new pathway for the degradation of nicotinamide ... more The present study was conducted to investigate a new pathway for the degradation of nicotinamide adenine dinucleotide (NAD) by Penicillium brevicompactum NRC 829 extracts. Enzymes involved in the hydrolysis of NAD, i.e. alkaline phosphatase, aminohydrolase and glycohydrolase were determined. Alkaline phosphatase was found to catalyse the sequential hydrolysis of two phosphate moieties of NAD molecule to nicotinamide riboside plus adenosine. Adenosine was then deaminated by aminohydrolase to inosine and ammonia. While glycohydrolase catalyzed the hydrolysis of the nicotinamide-ribosidic bond of NAD? to produce nicotinamide and ADP-ribose in equimolar amounts, enzyme purification through a 3-step purification procedure revealed the existence of two peaks of alkaline phosphatases, and one peak contained deaminase and glycohydrolase activities. NAD deaminase was purified to homogeneity as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis with an apparent molecular mass of 91 kDa. Characterization and determination of some of NAD aminohydrolase kinetic properties were conducted due to its biological role in the regulation of cellular NAD level. The results also revealed that NAD did not exert its feedback control on nicotinamide amidase produced by P. brevicompactum.

Research paper thumbnail of Screening and Media Optimization for Enhancing L-asparaginase Production, an Anticancer Agent, from Different Filamentous Fungi in Solid State Fermentation

British Biotechnology Journal, Jan 10, 2015

Aim: The aim of present study was to screen new potent fungal isolates and microorganisms possess... more Aim: The aim of present study was to screen new potent fungal isolates and microorganisms possessing extracellular L-asparaginase production capacity. In addition, optimization of cultural and environmental conditions required for enzyme production will be carried out for the highest Lasparaginase producer in solid state fermentation (SSF) technique using agro-industrial residues. Study Design: Screening and physiological studies on the formation of L-asparaginase by Trichoderma viride F2 in order to obtain the optimum cultural and environmental conditions required for enzyme production. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between July 2013 and June 2015. Methodology: Optimization of physical and nutritional parameters for enzyme production was investigated. Various locally available agro-industrial residues have been screened individually or as mixtures for L-asparaginase production. The combination of Rice husk (RH) with wheat bran Original Research Article Elshafei and El-Ghonemy; BBJ, 9(3): 1-15, 2015; Article no.BBJ.19728 2 (WB) (3:2) proved to be an efficient mixture for enzyme production as it gave the highest enzyme activity (71.87±3.19 U/g-ds) when compared to individual RH (66.71±2.76 U/g-ds) or WB (62.28±2.13 U/g-ds) substrates. Results: Maximal L-asparaginase production (113.43±5.11 U/g-ds) by T. viride F2 was obtained with moisture content of 75%, an inoculums size of 1 x 10 spores/ml and an initial medium pH of 5.0 when incubated at 28oC for four days. Presence of Tween 20 enhanced enzyme production by 1.19 folds. Glucose (1.0%), Casein (1.5%) and MgCl2 (0.05%) were found to be the best carbon, organic nitrogen and ion sources, respectively. Supplementation of the medium with NaNO3 (0.15%) as an inorganic nitrogen source further increased L-asparaginase production. Under these optimized conditions, L-asparaginase production by T. viride F2 was maximum with a yield of 276.5±13.4 U/g-ds in SSF, which was more than 19-fold enhancement in enzyme activity as compared to that obtained in the basal medium (SmF) (14.23±0.87 U/ml). Conclusion: The results suggest that choosing a suitable substrate coupled with optimization of different parameters can improves enzyme production markedly. Moreover, the production of Lasparaginase from a process based on RH and WB as substrates in SSF is economically attractive due to abundant substrates availability in agriculture-based countries with cheaper cost.

Research paper thumbnail of Antioxidant and antimicrobial activities of exopolysaccharides produced by a novel Aspergillus sp. DHE6 under optimized submerged fermentation conditions

Biocatalysis and agricultural biotechnology, Sep 1, 2021

Purpose: Cynara scolymus is a medicinal plant frequently used in traditional medicine for stomach... more Purpose: Cynara scolymus is a medicinal plant frequently used in traditional medicine for stomach and liver diseases. The purpose of the study was to identify the most suitable extraction solvent for maximum antioxidant and antimicrobial effect of fluidized bed extracts. Methods: The extracts were obtained by conventional maceration and fluidized bed extraction using 25, 50, 75 and 97 % v/v ethanol as solvent. The antioxidant effect of the extracts was determined by 2,2diphenyl-1-picrylhydrazyl (DPPH) method. The quantities of phenols and flavonoids, and the reducing power of the extracts were also determined. The antimicrobial activity of the extracts was tested against different microbial strains using agar well diffusion method. The minimum inhibiting concentration (MIC) of the fluidized bed extract was also determined. Results: The ethanol extract showed the highest antioxidant activity as well as yielded the largest quantity of polyphenolic compounds. For the extract obtained by fluidized bed technique, the optimum concentration of 10 mg/ml gave maximum antioxidant activity of 65.15 %. The MIC values obtained using the freeze-dried extract ranged from 5.0 mg/ml-15.0 mg/ml. The extracts showed significant inhibitory activity against the tested strains of Listeria innocua CMGB 218, Bacillus cereus CMGB 215 with MIC of 5 mg/ml but showed MIC of 15 mg/ml for the other strains. Conclusion: The results indicate that the freeze-dried extract from Cynara scolymus is capable of yielding nutritional supplements with antioxidant and antimicrobial activities.

Research paper thumbnail of Optimization of Culture Conditions for the Production of Extracellular Cellulases via Solid State Fermentation

British microbiology research journal, Jan 10, 2014

ABSTRACT Aim: The aims of the present study were to screen different filamentous fungi for extrac... more ABSTRACT Aim: The aims of the present study were to screen different filamentous fungi for extracellular cellulases production and to optimize solid-state fermentation medium and culture conditions to enhance cellulases production. Study Design: Using agro-industrial waste as raw material for the production of cellulases by a hyper cellulase producing fungus and evaluating the influence of various parameters to design a suitable SSF process for cellulase production. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between January 2013 and October 2013. Methodology: Different filamentous fungi were grown and maintained on potato dextrose agar slants at 28ºC for 7 days. The spores were washed down by distilled water. Then, 2.0 ml aliquots were used to inoculate 250 ml Erlenmeyer flasks, containing rice straw as the only carbon source. The inoculated flasks were incubated for 5 days at 28ºC. The enzymes were extracted by mixing homogenously the fermented substrate with 50 ml citrate phosphate buffer (0.1 M, pH 5.0) and agitated (150 rpm) for 1 hr. Pooled extracts were centrifuged at 5000 rpm for 15min and the clear supernatant was used as a source of extracellular enzyme. Results: Aspergillus oryzae NRRL 3484 exhibited relatively higher cellulases production. The optimum incubation period, temperature, and initial moisture level were reported on the 7th day, at 28°C, and 70%, respectively. Peptone proved to be the suitable nitrogen source followed by yeast extract, while pH 5.0 was ideal for cellulases production. Conclusion: Using ligninolytic fungi, including their enzymes, may be one potential alternative to provide a more practical and environmental-friendly approach for enhancing the nutritive value of rice straw. Moreover, the application of ligninolytic fungi or their enzymes combined with chemical pre-treatments to rice straw may be an alternative way to shorten the period of the incubation times and (or) decrease the amount of chemicals, effecting some synergy.

Research paper thumbnail of Improvement of lipid production from an oil-producing filamentous fungus, Penicillium brevicompactum NRC 829, through central composite statistical design

Annals of Microbiology, Aug 7, 2017

In the present study, 13 filamentous fungi were screened for their lipid production and an oleagi... more In the present study, 13 filamentous fungi were screened for their lipid production and an oleaginous fungus, Penicillium brevicompactum NRC 829, was found to be the highest lipid producer. Screening of various agroindustrial residues was performed and sunflower oil cake proved to be the best substrate for lipid production. A central composite design was employed to investigate the optimum concentrations of the most significant medium components required to improve the lipid production by P. brevicompactum. The results clearly revealed that the maximal lipid production of 8.014 ± 0.06 gL −1 (representing 57.6% lipid/dry biomass) was achieved by the fungus when grown for 6 days at 30°C under static condition in a medium containing sunflower oil cake, NaNO 3 and KCl at final concentrations of 8, 0.75 and 0.25 gL −1 , respectively. Gas chromatography-mass spectrometry analysis of P. brevicompactum lipid indicated that linoleic acid (LA) (C18:2-6, 9) was the most abundant fatty acid, accounting for up to 62% of the total fatty acid profile, followed by palmitoleic acid (C16:1, 16%) and linolenic acid (C18:3, 8%). These results suggest that P. brevicompactum NRC 829 may have potential for commercial development for the production of LA by fermentation using cheap raw material.

Research paper thumbnail of Immobilization and Characterization of a Thermostable Β-Glucosidase from Aspergillus Terreus NRRL 265

DOAJ (DOAJ: Directory of Open Access Journals), Feb 1, 2015

Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment ... more Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment in calcium-alginate beads. The activity of the free and immobilized enzymes as a function of pH, temperature, and periodic use were compared. Whey permeate, a byproduct of cheese industry, was served as an inexpensive medium, which made the process economical and reduced the cost of enzyme production and also reduced the environmental pollution. The results indicated that, the immobilized β-glucosidase was retained about 73 % of the original activity exhibited by the free enzyme. The optimum temperature for the enzyme activity was improved by 5ºC after immobilization. Immobilized β-glucosidase was exhibited great thermal stability, whereas, at 70ºC, the free enzyme lost its activity after 30 min of incubation, while the immobilized enzyme showed more stability in comparison to the free form as it retained about 13.4 % of its initial activity under the same conditions. Moreover, the pH stability was improved following immobilization, whereas, the immobilized enzyme was stable in pH ranging from 4.0 to 7.0 with no change in activity, while its stability slightly decreases for more alkaline or acidic conditions (retaining 82.4 % and 67.4 % of the initial activity at pH 8.0 and 3.5, after 1 h of incubation). The results also indicated the possibility of reusing Ca alginate-immobilized β-glucosidase in industrial applications for 10 cycles with 53.7 % retained activity. ARTICLE INFO

Research paper thumbnail of Optimization of extracellular ethanol-tolerant β-glucosidase production from a newly isolated Aspergillus sp. DHE7 via solid state fermentation using jojoba meal as substrate: purification and biochemical characterization for biofuel preparation

Journal of Genetic Engineering and Biotechnology, Mar 24, 2021

Background: The increasing demand and the continuous depletion in fossil fuels have persuaded res... more Background: The increasing demand and the continuous depletion in fossil fuels have persuaded researchers to investigate new sources of renewable energy. Bioethanol produced from cellulose could be a cost-effective and a viable alternative to petroleum. It is worth note that β-glucosidase plays a key role in the hydrolysis of cellulose and therefore in the production of bioethanol. This study aims to investigate a simple and standardized method for maximization of extracellular β-glucosidase production from a novel fungal isolate under solid-state fermentation using agro-industrial residues as the sole source of carbon and nitrogen. Furthermore, purification and characterization of β-glucosidase were performed to determine the conditions under which the enzyme displayed the highest performance. Results: A fungus identified genetically as a new Aspergillus sp. DHE7 was found to exhibit the highest extracellular β-glucosidase production among the sixty fungal isolates tested. Optimization of culture conditions improved the enzyme biosynthesis by 2.1-fold (174.6 ± 5.8 U/g of dry substrate) when the fungus grown for 72 h at 35°C on jojoba meal with 60% of initial substrate moisture, pH 6.0, and an inoculum size of 2.54 × 10 7 spores/mL. The enzyme was purified to homogeneity through a multi-step purification process. The purified β-glucosidase is monomeric with a molecular mass of 135 kDa as revealed by the SDS-PAGE analysis. Optimum activity was observed at 60°C and pH of 6.0, with a remarkable pH and thermal stability. The enzyme retained about 79% and 53% of its activity, after 1 h at 70°C and 80°C, respectively. The purified β-glucosidase hydrolysed a wide range of substrates but displaying its greater activity on p-nitrophenyl-β-D-glucopyranoside and cellobiose. The values of K m and V max on p-nitrophenyl β-D-glucopyranoside were 0.4 mM and 232.6 U/mL, respectively. Purified β-glucosidase displayed high catalytic activity (improved by 25%) in solutions contained ethanol up to 15%.

Research paper thumbnail of Purification, Characterization and Antitumor Activity of L-asparaginase from Penicillium brevicompactum NRC 829

British microbiology research journal, Jan 10, 2012

ABSTRACT Aim: The aims of this study were to attempt to extract, purify and characterize of Laspa... more ABSTRACT Aim: The aims of this study were to attempt to extract, purify and characterize of Lasparaginase, an antitumor agent, from Penicillium brevicompactum NRC 829. Study Design: Testing of antitumor activity of L-asparaginase against four different tumor human cell lines. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between June 2010 and November 2011. Methodology: Penicillium brevicompactum NRC 829, a local isolated strain from Culture Collection of the National Research Centre of Egypt, was grown and maintained on modified Czapek Dox medium. The fresh fungal biomass was thoroughly ground with washed cold sand. The cell contents were extracted with cold 0.1M Tris-HCl pH 8.0, thereafter, the slurry obtained was centrifuged at 5500 rpm for 15 min and the supernatant was directly used as the source of enzyme. The purification of L-asparaginase from crudeenzyme extracts of P. brevicompactum was achieved by a sequential multi-steps process starting by heat treatment for 20 min at 50ºC, followed by gel filtration on Sephadex G-100 column, and the most active fractions of L-asparaginase were dialyzed out, lyophilized and then loaded on a Sephadex G-200 column. Results: An intracellular glutaminase-free-L-asparaginase from Penicillium brevicompactum NRC 829 was purified to homogeneity with an apparent molecular mass (Mr) of 94 kDa. The purified enzyme was 151.12 fold with a final specific activity of 574.24 IU/mg protein and about 40% yield recovery. The purified L-asparaginase showed its maximal activity against L-asparagine when incubated at pH 8.0 at 37ºC for 30 min. Theenzyme was more stable at alkaline pH than the acidic one and thermally stable up to 60 min at 50-60ºC. L-asparaginase was highly specific for its natural substrate, L-asparagine with a Km value of 1.05 mM. The activity of L-asparaginase is activated by mono cations and various effectors including K+, Na+, 2-mercaptoethanol (2-ME), and reduced glutathione (r-GSH), whereas it is moderately inhibited by various divalent ions including Hg2+, Cu2+, and Ag+. Results indicated the involvement of sulfhydryl group(s) in the enzyme active site(s). The purified enzyme inhibited the growth of human cell line hepatocellular carcinoma (Hep-G2), with IC50 value of 43.3μg/ml. Conclusion: L-asparaginase purified from Penicillium brevicompactum NRC 829 is a potential candidate for medical applications.

Research paper thumbnail of Role of Microbial Enzymes in the Biodegradation of Rice Straw via Biotechnological Techniques

Research paper thumbnail of Thermo-alkali-stable lipase from a novel <i>Aspergillus niger</i>: statistical optimization, enzyme purification, immobilization and its application in biodiesel production

Preparative Biochemistry & Biotechnology, Aug 18, 2020

Abstract The influences of nutritional components affecting lipase production from the new Asperg... more Abstract The influences of nutritional components affecting lipase production from the new Aspergillus niger using wheat bran as substrate were studied by employing Plackett–Burman and central composite statistical designs. Out of the 11 medium components tested, sucrose, KH2PO4 and MgSO4 at final concentrations of 3.0, 1.0 and 0.5 g/L, respectively, were reported to contribute positively to enzyme production (20.09 ± 0.98 U/g ds). The enzyme was purified through ammonium sulfate precipitation followed by Sephadex G-100 gel filtration. Molecular mass of the purified lipase was 57 kDa as evident on SDS-PAGE. Different methods of immobilization were studied and the highest immobilization yield of 81.7 ± 2.18% was reported with agarose (2%) and the optimum temperature was raised from 45 to 50 °C. Immobilized lipase could retain 80% of its original activity at 60 °C after 1 hr of incubation, and was stable at pH values between neutral and alkaline pH. Lipase-catalyzed transesterification process of fungal oil resulted in a fatty acid methyl ester yield consisting of a high percentage of polyunsaturated fatty acids (83.6%), making it appropriate to be used as winter-grade biodiesel. The operational stability studies revealed that the immobilized lipase could keep 70% of its total activity after 5 cycles of the transesterification process.

Research paper thumbnail of Microbial Amidases and their Industrial Applications: A Review

Journal of Medical Microbiology and Diagnosis, 2015

Among the pediatric cancer in developed countries, acute leukemia ¬constitutes the major part wit... more Among the pediatric cancer in developed countries, acute leukemia ¬constitutes the major part with affecting 30-45 per 1,000,000 children each year. The effect of treatment varies with differences in patients clinical, immunologic and genetic characteristics. Therefore, the search for efficient drugs to solve this problem is being continued worldwide. Although several kinds of treatments are available, enzyme therapy is equally effective. Enzymes have been used as drugs; likewise L-asparaginase and L-glutaminase had received much attention in recent years due to their anticarcinogenic potential. These enzymes constitute one of the most biotechnologically and biomedically important group of therapeutic enzymes accounting for about 40% of the total worldwide enzyme sales. Various sources are found to be good producers of the enzymes: bacteria, fungi along with some of the plant and animal species. Food and Drug Administration and World Health Organization have approved L-asparaginase for the effective treatment of acute lymphoblastic leukemia and lymphsarcoma. L-asparaginase and L-glutaminase break down L-asparagine or L-glutamine into L-aspartic acid or L-glutamic acid, respectively, and ammonia. L-asparagine depletion results in nutritional deprivation, inhibition of protein synthesis, and subsequent apoptotic cell death in lymphoblasts. On the other hand, the ability of L-asparaginase to selectively hydrolyzes L-asparagine into L-aspartateis a potential way to reduce the amount of free L-asparagine in the starting materials of food production, thus reducing the imminent risk of generating a potential carcinogenic and neurotoxic acrylamide that formed from L-asparagine and reducing sugars in carbohydrate-containing foods (such as snacks and biscuits) when they are heated above 120oC. Therefore, the present review is an attempt to compile information on the sources, antino plastic action and industrial application of microbial amidases enzymes.

Research paper thumbnail of Therapeutic impact of purified Trichoderma viride l-asparaginase in murine model of liver cancer and in vitro Hep-G2 cell line

Journal of Genetic Engineering and Biotechnology, Mar 30, 2023

Background Hepatocellular carcinoma (HCC) is among the common cancers, but difficult to diagnose ... more Background Hepatocellular carcinoma (HCC) is among the common cancers, but difficult to diagnose and treat. l-asparaginase has been introduced in the treatment protocol of pediatric acute lymphoblastic leukemia (ALL) since the 1960s with a good outcome and increased survival rates to nearly 90%. Moreover, it has been found to have therapeutic potential in solid tumors. Production of glutaminase-free-l-asparaginase is of interest to avoid glutaminaserelated toxicity and hypersensitivity. In the current study, an extracellular l-asparaginase that is free of l-glutaminase was purified from the culture filtrate of an endophytic fungus Trichoderma viride. The cytotoxic effect of the purified enzyme was evaluated in vitro against a panel of human tumor cell lines and in vivo against male Wister albino mice intraperitoneally injected with diethyl nitrosamine (200 mg/kg bw), followed by (after 2 weeks) oral administration of carbon tetrachloride (2 mL/kg bw). This dose was repeated for 2 months, and after that, the blood samples were collected to estimate hepatic and renal injury markers, lipid profiles, and oxidative stress parameters. Results l-asparaginase was purified from T. viride culture filtrate with 36 purification folds, 688.1 U/mg specific activity, and 38.9% yield. The highest antiproliferative activity of the purified enzyme was observed against the hepatocellular carcinoma (Hep-G2) cell line, with an IC 50 of 21.2 g/mL, which was higher than that observed for MCF-7 (IC 50 34.2 g/mL). Comparing the DENA-intoxicated group to the negative control group, it can be demonstrated that l-asparaginase adjusted the levels of the liver function enzymes and the hepatic injury markers that had previously changed with DENA intoxication. DENA causes kidney dysfunction and altered serum albumin and creatinine levels as well. Administration of l-asparaginase was found to improve the levels of the tested biomarkers including kidney and liver function tests. l-asparaginase treatment of the DENA-intoxicated group resulted in a significant improvement in the liver and kidney tissues to near normal similar to the healthy control group. Conclusion The results suggest that this purified T. viride l-asparaginase may be able to delay the development of liver cancer and may be used as a potential candidate for future application in medicine as an anticancer medication.

Research paper thumbnail of Immobilization and characterization of a thermostable beta-glucosidase from Aspergillus terreus NRRL 265

The Journal of Microbiology, Biotechnology and Food Sciences, Feb 1, 2015

Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment ... more Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment in calcium-alginate beads. The activity of the free and immobilized enzymes as a function of pH, temperature, and periodic use were compared. Whey permeate, a byproduct of cheese industry, was served as an inexpensive medium, which made the process economical and reduced the cost of enzyme production and also reduced the environmental pollution. The results indicated that, the immobilized β-glucosidase was retained about 73 % of the original activity exhibited by the free enzyme. The optimum temperature for the enzyme activity was improved by 5ºC after immobilization. Immobilized β-glucosidase was exhibited great thermal stability, whereas, at 70ºC, the free enzyme lost its activity after 30 min of incubation, while the immobilized enzyme showed more stability in comparison to the free form as it retained about 13.4 % of its initial activity under the same conditions. Moreover, the pH stability was improved following immobilization, whereas, the immobilized enzyme was stable in pH ranging from 4.0 to 7.0 with no change in activity, while its stability slightly decreases for more alkaline or acidic conditions (retaining 82.4 % and 67.4 % of the initial activity at pH 8.0 and 3.5, after 1 h of incubation). The results also indicated the possibility of reusing Ca alginate-immobilized β-glucosidase in industrial applications for 10 cycles with 53.7 % retained activity. ARTICLE INFO

Research paper thumbnail of Extracellular β-d-fructofuranosidase from a novel Aspergillus sp. DHE1 with high potential for biotechnological applications: Purification and biochemical characterization

Biocatalysis and agricultural biotechnology, Mar 1, 2023

Research paper thumbnail of Extracellular Glutaminase-Free L-Asparaginase from Trichoderma Viride F2: Purification, Biochemical Characterization and Evaluation of Its Potential in Mitigating Acrylamide Formation in Starchy Fried Food

The Journal of Microbiology, Biotechnology and Food Sciences, Oct 1, 2021

Research paper thumbnail of Screening Studies on the Formation of Β-Glucosidase from Some Filamentous Fungi

Advances in food sciences, 2009

ABSTRACT Twenty-five strains of different filamentous fungi were screened for their abilities to ... more ABSTRACT Twenty-five strains of different filamentous fungi were screened for their abilities to produce intracellular β-glucosidase using modified D-cellobiose Czapek Doxs liquid medium. The results revealed that nearly all fungi under study (23 out of 25) produced β-glucosidase in different proportions. Aspergillus terreus NRRL 265, A. phoenicis NRRL 365, Penicillium martensii NRC 345, P. purpurescens NRC 846 and P. cyclopium NRC 881, producing considerable amounts of enzyme as compared to the other cultures, were selected for β-glucosidase quantitative assay. Among them, Aspergillus terreus NRRL 265 was found to produce high levels of an intracellular β-glucosidase besides the other two components of cellulase system, namely exo-(1,4)-β-D-glucanase ( FPase, EC 3.2.1.91 ) and endo-(1,4)-β-D-glucanase (carboxymethyl cellulase (CMCase), EC 3.2.1.4).

Research paper thumbnail of Optimization of Culture Conditions for the Highest Lipid Production from some Oleaginous Fungi for Biodiesel Preparation

Asian Journal of Applied Sciences, Oct 15, 2014

Ten different filamentous fungi were screened for their abilities to produce lipid. An oleaginous... more Ten different filamentous fungi were screened for their abilities to produce lipid. An oleaginous fungus strain Trichoderma viride NRC 314 was found to be the highest lipid producer (>20%) among the tested filamentous fungi. Optimization of culture conditions for maximum lipid production was investigated, and the results reported clearly indicated that, the potato dextrose (PD) liquid medium, at a concentration of 50 g/l for dextrose, was the most suitable medium for lipid production with initial pH 5.0, incubation temperature 28°C, after five days of incubation in a static condition. In addition, neither yeast extract nor sugar cane molasses supplement exhibits any significant effects on lipid accumulation. The GC/Ms analysis indicated that, the n-hexane lipid fraction of T. viride 314 was mainly composed of 30.01% Palmitoleic acid (C16:1), 23% Linoleic Acid (C18:2), 13% Linolenic acid (C18:3) and about 8% Erucic acid (C22:1). Furthermore, the total saturated fatty acids represented 8.3%, while that of the unsaturated was 81.74%. Therefore, our study suggests that, SCOs of oleaginous fungi could be used as a potential feedstock for biodiesel production with Trichoderma viride NRC 314 as a promising candidate.

Research paper thumbnail of Effective bioconversion of feather-waste Keratin by Thermo-Surfactant Stable Alkaline Keratinase produced from Aspergillus sp. DHE7 with promising biotechnological application in detergent formulations

Biocatalysis and agricultural biotechnology, Aug 1, 2021

Abstract Keratin-rich wastes are troublesome pollutants that their accumulation could lead to env... more Abstract Keratin-rich wastes are troublesome pollutants that their accumulation could lead to environmental problems. Microbial degradation of keratin wastes has emerged as an alternative bio-catalyst to steam-pressure cooking and alkali hydrolysis for the recycling of such residues to value-added products. The current work investigates the purification and biochemical characterisation of an extracellular keratinase from new Aspergillus sp. DHE7 using turkey feathers as substrate. The enzyme was purified 31-fold with a final yield of 37.5%. Purified keratinase is monomeric and its molecular mass was estimated to be 33 kDa as demonstrated on SDS-PAGE. The enzyme was active in wide range of pH (7.0–11) and temperature (37–70 °C) profiles with maximum activity at pH 8.5 and 60 °C. The activity was strongly suppressed by phenylmethylsulfonyl fluoride (93.4% inhibition) and moderately inhibited by EDTA (41.2% inhibition), suggesting that the current keratinase belongs to serine-metalloprotease. Bivalent cations, such as Ca2+, Zn2+, and Mn2+, enhanced enzyme activity by 165.7%, 176.3%, and 194.8%, respectively. The purified keratinase exhibited a wide proteolytic activity towards soluble and insoluble protein substrates displaying its greater activity toward casein, keratin, bovine serum albumin, and gelatin, followed by feathers, goat hair, and wool, and was substantially stable and compliant with surfactants and commercial laundry detergents. The Km, Vmax, Kcat and Kcat/Km values on keratin were 2.2 mg/mL, 2702.7 U/mL, 136.5 s−1 and 62.04 (s−1/mg mL−1), respectively. According to these characteristics, Aspergillus sp. DHE7 keratinase is suggested as a potential candidate for use in detergent formulations (as an additive) and in various biotechnological applications.

Research paper thumbnail of Extracellular Alkaline Lipase from a Novel Fungus Curvularia sp. DHE 5: Optimization of Physicochemical Parameters, Partial Purification and Characterization

Food Technology and Biotechnology, 2017

Thirty isolated fungal strains were screened for lipase production using Phenol Red plates, conta... more Thirty isolated fungal strains were screened for lipase production using Phenol Red plates, containing tributyrin as lipidic substrate, and a novel fungus identified genetically as Curvularia sp. DHE 5 was found as the most prominent strain. Various agro-industrial substrates were evaluated as inert supports for lipase production in solid-state fermentation. The highest yield of lipase ((83.4±2.2) U/g on dry mass basis) was reported with wheat bran medium after seven days of fermentation at pH=7.0, temperature of 30 °C, 70 % moisture content, inoculum size of 1.27•10 7 spore/mL and 2 % olive oil as an inducer. Supplementation of the medium with 0.05 % KCl as an ion source further increased lipase production to (88.9±1.2) U/g on dry mass basis. The enzyme was partially purified through ammonium sulphate fractionation (40 %) followed by dialysis, and its optimum pH and temperature were reported at 8.0 and 50 °C, respectively, with remarkable pH and thermal stability.

Research paper thumbnail of Production and purification of bioactive compounds with potent antimicrobial activity from a novel terrestrial fungus Aspergillus sp. DHE 4

Biocatalysis and agricultural biotechnology, Sep 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Purification and characterization of the enzymes involved in nicotinamide adenine dinucleotide degradation by Penicillium brevicompactum NRC 829

3 biotech, Jan 21, 2016

The present study was conducted to investigate a new pathway for the degradation of nicotinamide ... more The present study was conducted to investigate a new pathway for the degradation of nicotinamide adenine dinucleotide (NAD) by Penicillium brevicompactum NRC 829 extracts. Enzymes involved in the hydrolysis of NAD, i.e. alkaline phosphatase, aminohydrolase and glycohydrolase were determined. Alkaline phosphatase was found to catalyse the sequential hydrolysis of two phosphate moieties of NAD molecule to nicotinamide riboside plus adenosine. Adenosine was then deaminated by aminohydrolase to inosine and ammonia. While glycohydrolase catalyzed the hydrolysis of the nicotinamide-ribosidic bond of NAD? to produce nicotinamide and ADP-ribose in equimolar amounts, enzyme purification through a 3-step purification procedure revealed the existence of two peaks of alkaline phosphatases, and one peak contained deaminase and glycohydrolase activities. NAD deaminase was purified to homogeneity as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis with an apparent molecular mass of 91 kDa. Characterization and determination of some of NAD aminohydrolase kinetic properties were conducted due to its biological role in the regulation of cellular NAD level. The results also revealed that NAD did not exert its feedback control on nicotinamide amidase produced by P. brevicompactum.

Research paper thumbnail of Screening and Media Optimization for Enhancing L-asparaginase Production, an Anticancer Agent, from Different Filamentous Fungi in Solid State Fermentation

British Biotechnology Journal, Jan 10, 2015

Aim: The aim of present study was to screen new potent fungal isolates and microorganisms possess... more Aim: The aim of present study was to screen new potent fungal isolates and microorganisms possessing extracellular L-asparaginase production capacity. In addition, optimization of cultural and environmental conditions required for enzyme production will be carried out for the highest Lasparaginase producer in solid state fermentation (SSF) technique using agro-industrial residues. Study Design: Screening and physiological studies on the formation of L-asparaginase by Trichoderma viride F2 in order to obtain the optimum cultural and environmental conditions required for enzyme production. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between July 2013 and June 2015. Methodology: Optimization of physical and nutritional parameters for enzyme production was investigated. Various locally available agro-industrial residues have been screened individually or as mixtures for L-asparaginase production. The combination of Rice husk (RH) with wheat bran Original Research Article Elshafei and El-Ghonemy; BBJ, 9(3): 1-15, 2015; Article no.BBJ.19728 2 (WB) (3:2) proved to be an efficient mixture for enzyme production as it gave the highest enzyme activity (71.87±3.19 U/g-ds) when compared to individual RH (66.71±2.76 U/g-ds) or WB (62.28±2.13 U/g-ds) substrates. Results: Maximal L-asparaginase production (113.43±5.11 U/g-ds) by T. viride F2 was obtained with moisture content of 75%, an inoculums size of 1 x 10 spores/ml and an initial medium pH of 5.0 when incubated at 28oC for four days. Presence of Tween 20 enhanced enzyme production by 1.19 folds. Glucose (1.0%), Casein (1.5%) and MgCl2 (0.05%) were found to be the best carbon, organic nitrogen and ion sources, respectively. Supplementation of the medium with NaNO3 (0.15%) as an inorganic nitrogen source further increased L-asparaginase production. Under these optimized conditions, L-asparaginase production by T. viride F2 was maximum with a yield of 276.5±13.4 U/g-ds in SSF, which was more than 19-fold enhancement in enzyme activity as compared to that obtained in the basal medium (SmF) (14.23±0.87 U/ml). Conclusion: The results suggest that choosing a suitable substrate coupled with optimization of different parameters can improves enzyme production markedly. Moreover, the production of Lasparaginase from a process based on RH and WB as substrates in SSF is economically attractive due to abundant substrates availability in agriculture-based countries with cheaper cost.

Research paper thumbnail of Antioxidant and antimicrobial activities of exopolysaccharides produced by a novel Aspergillus sp. DHE6 under optimized submerged fermentation conditions

Biocatalysis and agricultural biotechnology, Sep 1, 2021

Purpose: Cynara scolymus is a medicinal plant frequently used in traditional medicine for stomach... more Purpose: Cynara scolymus is a medicinal plant frequently used in traditional medicine for stomach and liver diseases. The purpose of the study was to identify the most suitable extraction solvent for maximum antioxidant and antimicrobial effect of fluidized bed extracts. Methods: The extracts were obtained by conventional maceration and fluidized bed extraction using 25, 50, 75 and 97 % v/v ethanol as solvent. The antioxidant effect of the extracts was determined by 2,2diphenyl-1-picrylhydrazyl (DPPH) method. The quantities of phenols and flavonoids, and the reducing power of the extracts were also determined. The antimicrobial activity of the extracts was tested against different microbial strains using agar well diffusion method. The minimum inhibiting concentration (MIC) of the fluidized bed extract was also determined. Results: The ethanol extract showed the highest antioxidant activity as well as yielded the largest quantity of polyphenolic compounds. For the extract obtained by fluidized bed technique, the optimum concentration of 10 mg/ml gave maximum antioxidant activity of 65.15 %. The MIC values obtained using the freeze-dried extract ranged from 5.0 mg/ml-15.0 mg/ml. The extracts showed significant inhibitory activity against the tested strains of Listeria innocua CMGB 218, Bacillus cereus CMGB 215 with MIC of 5 mg/ml but showed MIC of 15 mg/ml for the other strains. Conclusion: The results indicate that the freeze-dried extract from Cynara scolymus is capable of yielding nutritional supplements with antioxidant and antimicrobial activities.

Research paper thumbnail of Optimization of Culture Conditions for the Production of Extracellular Cellulases via Solid State Fermentation

British microbiology research journal, Jan 10, 2014

ABSTRACT Aim: The aims of the present study were to screen different filamentous fungi for extrac... more ABSTRACT Aim: The aims of the present study were to screen different filamentous fungi for extracellular cellulases production and to optimize solid-state fermentation medium and culture conditions to enhance cellulases production. Study Design: Using agro-industrial waste as raw material for the production of cellulases by a hyper cellulase producing fungus and evaluating the influence of various parameters to design a suitable SSF process for cellulase production. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between January 2013 and October 2013. Methodology: Different filamentous fungi were grown and maintained on potato dextrose agar slants at 28ºC for 7 days. The spores were washed down by distilled water. Then, 2.0 ml aliquots were used to inoculate 250 ml Erlenmeyer flasks, containing rice straw as the only carbon source. The inoculated flasks were incubated for 5 days at 28ºC. The enzymes were extracted by mixing homogenously the fermented substrate with 50 ml citrate phosphate buffer (0.1 M, pH 5.0) and agitated (150 rpm) for 1 hr. Pooled extracts were centrifuged at 5000 rpm for 15min and the clear supernatant was used as a source of extracellular enzyme. Results: Aspergillus oryzae NRRL 3484 exhibited relatively higher cellulases production. The optimum incubation period, temperature, and initial moisture level were reported on the 7th day, at 28°C, and 70%, respectively. Peptone proved to be the suitable nitrogen source followed by yeast extract, while pH 5.0 was ideal for cellulases production. Conclusion: Using ligninolytic fungi, including their enzymes, may be one potential alternative to provide a more practical and environmental-friendly approach for enhancing the nutritive value of rice straw. Moreover, the application of ligninolytic fungi or their enzymes combined with chemical pre-treatments to rice straw may be an alternative way to shorten the period of the incubation times and (or) decrease the amount of chemicals, effecting some synergy.

Research paper thumbnail of Improvement of lipid production from an oil-producing filamentous fungus, Penicillium brevicompactum NRC 829, through central composite statistical design

Annals of Microbiology, Aug 7, 2017

In the present study, 13 filamentous fungi were screened for their lipid production and an oleagi... more In the present study, 13 filamentous fungi were screened for their lipid production and an oleaginous fungus, Penicillium brevicompactum NRC 829, was found to be the highest lipid producer. Screening of various agroindustrial residues was performed and sunflower oil cake proved to be the best substrate for lipid production. A central composite design was employed to investigate the optimum concentrations of the most significant medium components required to improve the lipid production by P. brevicompactum. The results clearly revealed that the maximal lipid production of 8.014 ± 0.06 gL −1 (representing 57.6% lipid/dry biomass) was achieved by the fungus when grown for 6 days at 30°C under static condition in a medium containing sunflower oil cake, NaNO 3 and KCl at final concentrations of 8, 0.75 and 0.25 gL −1 , respectively. Gas chromatography-mass spectrometry analysis of P. brevicompactum lipid indicated that linoleic acid (LA) (C18:2-6, 9) was the most abundant fatty acid, accounting for up to 62% of the total fatty acid profile, followed by palmitoleic acid (C16:1, 16%) and linolenic acid (C18:3, 8%). These results suggest that P. brevicompactum NRC 829 may have potential for commercial development for the production of LA by fermentation using cheap raw material.

Research paper thumbnail of Immobilization and Characterization of a Thermostable Β-Glucosidase from Aspergillus Terreus NRRL 265

DOAJ (DOAJ: Directory of Open Access Journals), Feb 1, 2015

Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment ... more Partially purified β-glucosidase from Aspergillus terreus NRRL 265 was immobilized by entrapment in calcium-alginate beads. The activity of the free and immobilized enzymes as a function of pH, temperature, and periodic use were compared. Whey permeate, a byproduct of cheese industry, was served as an inexpensive medium, which made the process economical and reduced the cost of enzyme production and also reduced the environmental pollution. The results indicated that, the immobilized β-glucosidase was retained about 73 % of the original activity exhibited by the free enzyme. The optimum temperature for the enzyme activity was improved by 5ºC after immobilization. Immobilized β-glucosidase was exhibited great thermal stability, whereas, at 70ºC, the free enzyme lost its activity after 30 min of incubation, while the immobilized enzyme showed more stability in comparison to the free form as it retained about 13.4 % of its initial activity under the same conditions. Moreover, the pH stability was improved following immobilization, whereas, the immobilized enzyme was stable in pH ranging from 4.0 to 7.0 with no change in activity, while its stability slightly decreases for more alkaline or acidic conditions (retaining 82.4 % and 67.4 % of the initial activity at pH 8.0 and 3.5, after 1 h of incubation). The results also indicated the possibility of reusing Ca alginate-immobilized β-glucosidase in industrial applications for 10 cycles with 53.7 % retained activity. ARTICLE INFO

Research paper thumbnail of Optimization of extracellular ethanol-tolerant β-glucosidase production from a newly isolated Aspergillus sp. DHE7 via solid state fermentation using jojoba meal as substrate: purification and biochemical characterization for biofuel preparation

Journal of Genetic Engineering and Biotechnology, Mar 24, 2021

Background: The increasing demand and the continuous depletion in fossil fuels have persuaded res... more Background: The increasing demand and the continuous depletion in fossil fuels have persuaded researchers to investigate new sources of renewable energy. Bioethanol produced from cellulose could be a cost-effective and a viable alternative to petroleum. It is worth note that β-glucosidase plays a key role in the hydrolysis of cellulose and therefore in the production of bioethanol. This study aims to investigate a simple and standardized method for maximization of extracellular β-glucosidase production from a novel fungal isolate under solid-state fermentation using agro-industrial residues as the sole source of carbon and nitrogen. Furthermore, purification and characterization of β-glucosidase were performed to determine the conditions under which the enzyme displayed the highest performance. Results: A fungus identified genetically as a new Aspergillus sp. DHE7 was found to exhibit the highest extracellular β-glucosidase production among the sixty fungal isolates tested. Optimization of culture conditions improved the enzyme biosynthesis by 2.1-fold (174.6 ± 5.8 U/g of dry substrate) when the fungus grown for 72 h at 35°C on jojoba meal with 60% of initial substrate moisture, pH 6.0, and an inoculum size of 2.54 × 10 7 spores/mL. The enzyme was purified to homogeneity through a multi-step purification process. The purified β-glucosidase is monomeric with a molecular mass of 135 kDa as revealed by the SDS-PAGE analysis. Optimum activity was observed at 60°C and pH of 6.0, with a remarkable pH and thermal stability. The enzyme retained about 79% and 53% of its activity, after 1 h at 70°C and 80°C, respectively. The purified β-glucosidase hydrolysed a wide range of substrates but displaying its greater activity on p-nitrophenyl-β-D-glucopyranoside and cellobiose. The values of K m and V max on p-nitrophenyl β-D-glucopyranoside were 0.4 mM and 232.6 U/mL, respectively. Purified β-glucosidase displayed high catalytic activity (improved by 25%) in solutions contained ethanol up to 15%.

Research paper thumbnail of Purification, Characterization and Antitumor Activity of L-asparaginase from Penicillium brevicompactum NRC 829

British microbiology research journal, Jan 10, 2012

ABSTRACT Aim: The aims of this study were to attempt to extract, purify and characterize of Laspa... more ABSTRACT Aim: The aims of this study were to attempt to extract, purify and characterize of Lasparaginase, an antitumor agent, from Penicillium brevicompactum NRC 829. Study Design: Testing of antitumor activity of L-asparaginase against four different tumor human cell lines. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between June 2010 and November 2011. Methodology: Penicillium brevicompactum NRC 829, a local isolated strain from Culture Collection of the National Research Centre of Egypt, was grown and maintained on modified Czapek Dox medium. The fresh fungal biomass was thoroughly ground with washed cold sand. The cell contents were extracted with cold 0.1M Tris-HCl pH 8.0, thereafter, the slurry obtained was centrifuged at 5500 rpm for 15 min and the supernatant was directly used as the source of enzyme. The purification of L-asparaginase from crudeenzyme extracts of P. brevicompactum was achieved by a sequential multi-steps process starting by heat treatment for 20 min at 50ºC, followed by gel filtration on Sephadex G-100 column, and the most active fractions of L-asparaginase were dialyzed out, lyophilized and then loaded on a Sephadex G-200 column. Results: An intracellular glutaminase-free-L-asparaginase from Penicillium brevicompactum NRC 829 was purified to homogeneity with an apparent molecular mass (Mr) of 94 kDa. The purified enzyme was 151.12 fold with a final specific activity of 574.24 IU/mg protein and about 40% yield recovery. The purified L-asparaginase showed its maximal activity against L-asparagine when incubated at pH 8.0 at 37ºC for 30 min. Theenzyme was more stable at alkaline pH than the acidic one and thermally stable up to 60 min at 50-60ºC. L-asparaginase was highly specific for its natural substrate, L-asparagine with a Km value of 1.05 mM. The activity of L-asparaginase is activated by mono cations and various effectors including K+, Na+, 2-mercaptoethanol (2-ME), and reduced glutathione (r-GSH), whereas it is moderately inhibited by various divalent ions including Hg2+, Cu2+, and Ag+. Results indicated the involvement of sulfhydryl group(s) in the enzyme active site(s). The purified enzyme inhibited the growth of human cell line hepatocellular carcinoma (Hep-G2), with IC50 value of 43.3μg/ml. Conclusion: L-asparaginase purified from Penicillium brevicompactum NRC 829 is a potential candidate for medical applications.

Research paper thumbnail of Role of Microbial Enzymes in the Biodegradation of Rice Straw via Biotechnological Techniques

Research paper thumbnail of Thermo-alkali-stable lipase from a novel <i>Aspergillus niger</i>: statistical optimization, enzyme purification, immobilization and its application in biodiesel production

Preparative Biochemistry & Biotechnology, Aug 18, 2020

Abstract The influences of nutritional components affecting lipase production from the new Asperg... more Abstract The influences of nutritional components affecting lipase production from the new Aspergillus niger using wheat bran as substrate were studied by employing Plackett–Burman and central composite statistical designs. Out of the 11 medium components tested, sucrose, KH2PO4 and MgSO4 at final concentrations of 3.0, 1.0 and 0.5 g/L, respectively, were reported to contribute positively to enzyme production (20.09 ± 0.98 U/g ds). The enzyme was purified through ammonium sulfate precipitation followed by Sephadex G-100 gel filtration. Molecular mass of the purified lipase was 57 kDa as evident on SDS-PAGE. Different methods of immobilization were studied and the highest immobilization yield of 81.7 ± 2.18% was reported with agarose (2%) and the optimum temperature was raised from 45 to 50 °C. Immobilized lipase could retain 80% of its original activity at 60 °C after 1 hr of incubation, and was stable at pH values between neutral and alkaline pH. Lipase-catalyzed transesterification process of fungal oil resulted in a fatty acid methyl ester yield consisting of a high percentage of polyunsaturated fatty acids (83.6%), making it appropriate to be used as winter-grade biodiesel. The operational stability studies revealed that the immobilized lipase could keep 70% of its total activity after 5 cycles of the transesterification process.

Research paper thumbnail of Microbial Amidases and their Industrial Applications: A Review

Journal of Medical Microbiology and Diagnosis, 2015

Among the pediatric cancer in developed countries, acute leukemia ¬constitutes the major part wit... more Among the pediatric cancer in developed countries, acute leukemia ¬constitutes the major part with affecting 30-45 per 1,000,000 children each year. The effect of treatment varies with differences in patients clinical, immunologic and genetic characteristics. Therefore, the search for efficient drugs to solve this problem is being continued worldwide. Although several kinds of treatments are available, enzyme therapy is equally effective. Enzymes have been used as drugs; likewise L-asparaginase and L-glutaminase had received much attention in recent years due to their anticarcinogenic potential. These enzymes constitute one of the most biotechnologically and biomedically important group of therapeutic enzymes accounting for about 40% of the total worldwide enzyme sales. Various sources are found to be good producers of the enzymes: bacteria, fungi along with some of the plant and animal species. Food and Drug Administration and World Health Organization have approved L-asparaginase for the effective treatment of acute lymphoblastic leukemia and lymphsarcoma. L-asparaginase and L-glutaminase break down L-asparagine or L-glutamine into L-aspartic acid or L-glutamic acid, respectively, and ammonia. L-asparagine depletion results in nutritional deprivation, inhibition of protein synthesis, and subsequent apoptotic cell death in lymphoblasts. On the other hand, the ability of L-asparaginase to selectively hydrolyzes L-asparagine into L-aspartateis a potential way to reduce the amount of free L-asparagine in the starting materials of food production, thus reducing the imminent risk of generating a potential carcinogenic and neurotoxic acrylamide that formed from L-asparagine and reducing sugars in carbohydrate-containing foods (such as snacks and biscuits) when they are heated above 120oC. Therefore, the present review is an attempt to compile information on the sources, antino plastic action and industrial application of microbial amidases enzymes.

Research paper thumbnail of Therapeutic impact of purified Trichoderma viride l-asparaginase in murine model of liver cancer and in vitro Hep-G2 cell line

Journal of Genetic Engineering and Biotechnology, Mar 30, 2023

Background Hepatocellular carcinoma (HCC) is among the common cancers, but difficult to diagnose ... more Background Hepatocellular carcinoma (HCC) is among the common cancers, but difficult to diagnose and treat. l-asparaginase has been introduced in the treatment protocol of pediatric acute lymphoblastic leukemia (ALL) since the 1960s with a good outcome and increased survival rates to nearly 90%. Moreover, it has been found to have therapeutic potential in solid tumors. Production of glutaminase-free-l-asparaginase is of interest to avoid glutaminaserelated toxicity and hypersensitivity. In the current study, an extracellular l-asparaginase that is free of l-glutaminase was purified from the culture filtrate of an endophytic fungus Trichoderma viride. The cytotoxic effect of the purified enzyme was evaluated in vitro against a panel of human tumor cell lines and in vivo against male Wister albino mice intraperitoneally injected with diethyl nitrosamine (200 mg/kg bw), followed by (after 2 weeks) oral administration of carbon tetrachloride (2 mL/kg bw). This dose was repeated for 2 months, and after that, the blood samples were collected to estimate hepatic and renal injury markers, lipid profiles, and oxidative stress parameters. Results l-asparaginase was purified from T. viride culture filtrate with 36 purification folds, 688.1 U/mg specific activity, and 38.9% yield. The highest antiproliferative activity of the purified enzyme was observed against the hepatocellular carcinoma (Hep-G2) cell line, with an IC 50 of 21.2 g/mL, which was higher than that observed for MCF-7 (IC 50 34.2 g/mL). Comparing the DENA-intoxicated group to the negative control group, it can be demonstrated that l-asparaginase adjusted the levels of the liver function enzymes and the hepatic injury markers that had previously changed with DENA intoxication. DENA causes kidney dysfunction and altered serum albumin and creatinine levels as well. Administration of l-asparaginase was found to improve the levels of the tested biomarkers including kidney and liver function tests. l-asparaginase treatment of the DENA-intoxicated group resulted in a significant improvement in the liver and kidney tissues to near normal similar to the healthy control group. Conclusion The results suggest that this purified T. viride l-asparaginase may be able to delay the development of liver cancer and may be used as a potential candidate for future application in medicine as an anticancer medication.