Wensheng Qin - Academia.edu (original) (raw)

Papers by Wensheng Qin

Research paper thumbnail of Effect of Laponite Nanoparticles on Growth Characteristics and Chlorophyll Content of Chlorella sp

Water, Air, & Soil Pollution

Research paper thumbnail of Enhancement of saccharification of corn stover by cellulolytic enzyme produced from biomass-degrading bacteria

BioResources, 2022

Enzymatic saccharification of corn stover can be enhanced by partially replacing commercial enzym... more Enzymatic saccharification of corn stover can be enhanced by partially replacing commercial enzymes with bacterial crude enzyme extracts. Thus, in this study, three bacteria (Bacillus sp. A0, Bacillus sp. CH20S1, and Exiguobacterium sp. AS2B) were cultured in a media with corn stover as the substrate to produce crude enzyme extract and saccharify corn stover. The cultural conditions were monitored and optimized to maximize CMCase and xylanase activity in the crude enzyme extracts. After 72 h of hydrolysis of corn stover with diluted crude enzymes (DCE) from the three strains, reducing sugars ranging from 48.2 to 71.7 mg g-1 were released from non-pretreated and pretreated corn stover. Furthermore, the maximum reducing sugars of 316 and 321 mg g-1 were observed when 12 and 4 FPU g-1 of commercial cellulase were added to the DCE of the CH20S1 strain, respectively. It was shown that an effective combination of bacterial DCE with commercial enzymes could achieve higher saccharification ...

Research paper thumbnail of Enzyme Production and Lignin Degradation by Four Basidiomycetous Fungi in Submerged Fermentation of Peat Containing Medium

International Journal of Biology, 2011

Biomass decomposing abilities of four basidiomycetous fungi (Pleurotus ostreatus sensu Cooke, Cor... more Biomass decomposing abilities of four basidiomycetous fungi (Pleurotus ostreatus sensu Cooke, Coriolus versicolor (L.) Quel., Tyromyces albidus (Schaeff.) Donk, and Trametes gallica Fr.) were studied using statically submerged media containing peat. The laccase, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), and total cellulase enzymatic profiles of the four fungi were assessed. The results revealed that laccase is the predominant ligninolytic enzyme secreted during the statically submerged fermentation process using peat as the substrate. T. gallica was the most active laccase producer with about 103 U/L at day 25. C. versicolor produced relatively higher levels of MnP than the other three basidiomycetous fungi (10 U/L). No significant LiP activity was detected in any of the four white rot fungi (WRF). Furthermore, the production of total cellulase by the four white rot fungi is low, which is beneficial to the selectivity of the bio-delignification. The Klason lignin content www.ccsenet.org/ijb

Research paper thumbnail of Effect of different carbon sources on cellulase production by Hypocrea jecorina (Trichoderma reesei) strains

International journal of biochemistry and molecular biology, 2011

The ascomycete Hypocrea jecorina, an industrial (hemi)cellulase producer, can efficiently degrade... more The ascomycete Hypocrea jecorina, an industrial (hemi)cellulase producer, can efficiently degrade plant polysaccharides. At present, the biology underlying cellulase hyperproduction of T. reesei, and the conditions for the enzyme induction, are not completely understood. In the current study, three different strains of T. reesei, including QM6a (wild-type), and mutants QM9414 and RUT-C30, were grown on 7 soluble and 7 insoluble carbon sources, with the later group including 4 pure polysaccharides and 3 lignocelluloses. Time course experiments showed that maximum cellulase activity of QM6a and QM9414 strains, for the majority of tested carbon sources, occurred at 120 hrs, while RUT-C30 had the greatest cellulase activity around 72 hrs. Maximum cellulase production was observed to be 0.035, 0.42 and 0.33 µmol glucose equivalents using microcrystalline celluloses for QM6a, QM9414, and RUTC-30, respectively. Increased cellulase production was positively correlated in QM9414 and negative...

Research paper thumbnail of Soluble human core 2 beta6-G1cNAc-transferase C2GnT1 requires its conserved Cys residues for full activity

Research paper thumbnail of Purification of crude glycerol using acidification: effects of acid types and product characterization

Purification of crude glycerol is essential for its applications for high-value products. In this... more Purification of crude glycerol is essential for its applications for high-value products. In this study, crude glycerol was purified by acidification using sulfuric, hydrochloric or phosphoric acid, and the results were compared. Phosphoric acid was found to be the best purifying agent among the others. Acidification of a biodiesel plant waste crude glycerol (containing approximately 13 wt% glycerol and 6 wt% ash) for a total processing time of 1 h, produced a purified product containing approximately 96 wt% glycerol, and 0.7 wt% ash. Effects of pH values on the purification efficiency were investigated. The crude glycerol and the purified products were extensively characterized.

Research paper thumbnail of Discovery, Modification and Production of T4 Lysozyme for Industrial and Medical Uses

International Journal of Biology, 2014

Lysozyme has attracted immense attention as an antimicrobial agent because of its ability to lyse... more Lysozyme has attracted immense attention as an antimicrobial agent because of its ability to lyse the bacterial cell wall. It is found in a wide variety of body fluids and in cells of the innate immune system. Lysozyme can act as muramidase or as a Cationic Antimicrobial Peptide (CAMP). Lysozyme has many applications in the medical and industrial fields. Based on enzyme nomenclature, lysozyme is classified as a glycosylase under the group hydrolases. This manuscript covers a fundamental review of lysozyme in terms of discovery, history, functions and various sources and types of lysozyme. The biological and molecular structure is discussed as well as notable bioengineering and protein modifications. Furthermore, the mechanisms of resistance to lysozyme in microorganisms have also been discussed. Lastly, different methods that have been developed for detecting and measuring the activity of lysozyme are outlined. Although, a recombinant lysozyme has not yet been produced, several studies have attempted to generate a modified lysozyme either for large-scale production or that which is more suitable for industrialization purposes.

Research paper thumbnail of The Human Trifunctional Enzyme ofde NovoPurine Biosynthesis: Heterologous Expression, Purification, and Preliminary Characterization

Protein Expression and Purification, 1998

Research paper thumbnail of Catalytic conversion of glycerol to oxygenated fuel additive in a continuous flow reactor: Process optimization

Fuel, 2014

h i g h l i g h t s A continuous flow process for synthesis of solketal from glycerol was optimiz... more h i g h l i g h t s A continuous flow process for synthesis of solketal from glycerol was optimized. A maximum yield of 94 ± 2% was obtained at optimum conditions. Presence of impurities (salt and water) demonstrated an adverse effect on the yield. The catalyst after 24 h on-stream use proved to be regenerable.

Research paper thumbnail of Thermodynamic and kinetic studies of a catalytic process to convert glycerol into solketal as an oxygenated fuel additive

Fuel, 2014

h i g h l i g h t s Thermodynamics and kinetics of glycerol ketalization were studied for the fir... more h i g h l i g h t s Thermodynamics and kinetics of glycerol ketalization were studied for the first time. External mass transfer resistance was completely eliminated above 400 rpm. Moisture content demonstrated an adverse effect on the yield of solketal. Kinetics of the reaction was modeled by Langmuir-Hinshelwood rate expression. The activation energy for the reaction was determined to be 55.6 kJ mol À1 .

Research paper thumbnail of Antibacterial activity of northern Ontario medicinal plant extracts

Canadian Journal of Plant Science, 2014

Hassan, H. M., Jiang, Z.-H., Asmussen, C., McDonald, E. and Qin, W. 2014. Antibacterial activity ... more Hassan, H. M., Jiang, Z.-H., Asmussen, C., McDonald, E. and Qin, W. 2014. Antibacterial activity of northern Ontario medicinal plant extracts. Can. J. Plant Sci. 94: 417–424. In the present study, the antibacterial activity (in vitro) of the leaf and/or flower crude extracts of Anaphalis margaritacea (L.) Benth & Hook.f., Grindelia squarrosa (Pursh) Dunal, Apocynum androsaemifolium L., Arctostaphylos uva-ursi (L.) Spreng, Cornus canadensis L. and Xanthium strumarium L. medicinal plants was analyzed through the hole-plate diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays against Escherichia coli, Aeromonas caviae, Paenibacillus alvei, Micrococcus luteus, Mycobacterium avium subsp. avium and Bacillus cereus bacteria. In addition, the time-kill dynamic processes of these extracts against A. caviae, B. cereus, P. alvei, and M. luteus bacteria were also tested. The leaf and flower extracts of Anap. margaritacea and G. squarrosa possess ...

Research paper thumbnail of Review: Northern Ontario medicinal plants

Canadian Journal of Plant Science, 2012

Hassan, H. M., Jiang, Z.-H., Syed, T. A. and Qin, W. 2012. Review: Northern Ontario medicinal pla... more Hassan, H. M., Jiang, Z.-H., Syed, T. A. and Qin, W. 2012. Review: Northern Ontario medicinal plants. Can. J. Plant Sci. 92: 815–828. The majority of scholarly investigations conducted in the 20th century have provided the incentive for establishing plants as sources of diverse phytochemicals. With infectious and cancerous diseases causing millions of mortalities worldwide, and the advent of resistant strains, the discovery of new antimicrobial and anticancer agents is crucial. Hence, included in this review is a novel list of 48 northern Ontario medicinal plants that may be sources of antifungal, antibacterial and/or anticancer phytochemicals. A total of two ferns and allied plants, two sedges and grasses, six trees, four shrubs, one vine and 33 herbs were identified. These plants were accumulated through interviews with native Elders and a survey of ethnobotanical literature on northern Canadian species of medicinal plants. We also present a critical review of their potential cons...

Research paper thumbnail of Soluble human core 2 β6-N-acetylglucosaminyltransferase C2GnT1 requires its conserved cysteine residues for full activity

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics, 2003

Research paper thumbnail of A new continuous-flow process for catalytic conversion of glycerol to oxygenated fuel additive: Catalyst screening

Research paper thumbnail of Newly Isolated and Characterized Bacteria with

Research paper thumbnail of Agave Biomass is Excellent for Production of Bioethanol and Xylitol Using Bacillus Strain 65S3 and Pseudomonas Strain CDS3

Journal of Biobased Materials and Bioenergy, 2014

Research paper thumbnail of The prospects of cellulase-producing bacteria for the bioconversion of lignocellulosic biomass

International journal of biological sciences, 2009

Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversi... more Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. However, the biorefining process remains economically unfeasible due to a lack of biocatalysts that can overcome costly hurdles such as cooling from high temperature, pumping of oxygen/stirring, and, neutralization from acidic or basic pH. The extreme environmental resistance of bacteria permits screening and isolation of novel cellulases to help overcome these challenges. Rapid, efficient cellulase screening techniques, using cellulase assays and metagenomic libraries, are a must. Rare cellulases with activities on soluble and crystalline cellulose have been isolated from strains of Paenibacillus and Bacillus and shown to have high thermostability and/or activity over a wide pH spectrum. While novel cellulases from strains like Cellulomonas flavigena and Terendinibacter turnerae, produce multifunctional cellulases with broader substrate utilization. These ...

Research paper thumbnail of Overexpression of D-xylose reductase (xyl1) gene and antisense inhibition of D-xylulokinase (xyiH) gene increase xylitol production in Trichoderma reesei

BioMed research international, 2014

T. reesei is an efficient cellulase producer and biomass degrader. To improve xylitol production ... more T. reesei is an efficient cellulase producer and biomass degrader. To improve xylitol production in Trichoderma reesei strains by genetic engineering, two approaches were used in this study. First, the presumptive D-xylulokinase gene in T. reesei (xyiH), which has high homology to known fungi D-xylulokinase genes, was silenced by transformation of T. reesei QM9414 strain with an antisense construct to create strain S6-2-2. The expression of the xyiH gene in the transformed strain S6-2-2 decreased at the mRNA level, and D-xylulokinase activity decreased after 48 h of incubation. This led to an increase in xylitol production from undetectable levels in wild-type T. reesei QM9414 to 8.6 mM in S6-2-2. The T. reesei Δxdh is a xylose dehydrogenase knockout strain with increased xylitol production compared to the wild-type T. reesei QM9414 (22.8 mM versus undetectable). The copy number of the xylose reductase gene (xyl1) in T. reesei Δxdh strain was increased by genetic engineering to crea...

Research paper thumbnail of Increased expression of β-glucosidase A in Clostridium thermocellum 27405 significantly increases cellulase activity

Bioengineered

β-glucosidase A (bglA) in Clostridium thermocellum 27405 was increased by expression from shuttle... more β-glucosidase A (bglA) in Clostridium thermocellum 27405 was increased by expression from shuttle vector pIBglA in attempts to increase cellulase activity and ethanol titer by lowering the end product inhibition of cellulase. Through a modified electrotransformation protocol C. thermocellum transformant (+MCbglA) harbouring pIBglA was produced. The β-glucosidase activity of +MCbglA was 2.3- and 1.6-fold greater than wild-type (WT) during late log and stationary phases of growth. Similarly, total cellulase activity of +MCbglA was shown to be 1.7-, 2.3- and 1.6-fold greater than WT during, log, late log and stationary phases of growth. However, there was no significant correlation found between increased cellulase activity and increased ethanol titers for +MCbglA compared with the WT. C. thermocellum has industrial potential for consolidated bioprocessing (CBP) to make a more cost effective production of biofuels; however, the hydrolysis rate of the strain is still hindered by end pro...

Research paper thumbnail of Characterization of some efficient cellulase producing bacteria isolated from paper mill sludges and organic fertilizers

International journal of biochemistry and molecular biology, 2011

The wide variety of bacteria in the environment permits screening for more efficient cellulases t... more The wide variety of bacteria in the environment permits screening for more efficient cellulases to help overcome current challenges in biofuel production. This study focuses on the isolation of efficient cellulase producing bacteria found in organic fertilizers and paper mill sludges which can be considered for use in large scale biorefining. Pure isolate cultures were screened for cellulase activity. Six isolates: S1, S2, S3, S4, E2, and E4, produced halos greater in diameter than the positive control (Cellulomonas xylanilytica), suggesting high cellulase activities. A portion of the 16S rDNA genes of cellulase positive isolates were amplified and sequenced, then BLASTed to determine likely genera. Phylogenetic analysis revealed genera belonging to two major Phyla of Gram positive bacteria: Firmicutes and Actinobacteria. All isolates were tested for the visible degradation of filter paper; only isolates E2 and E4 (Paenibacillus species) were observed to completely break down filter...

Research paper thumbnail of Effect of Laponite Nanoparticles on Growth Characteristics and Chlorophyll Content of Chlorella sp

Water, Air, & Soil Pollution

Research paper thumbnail of Enhancement of saccharification of corn stover by cellulolytic enzyme produced from biomass-degrading bacteria

BioResources, 2022

Enzymatic saccharification of corn stover can be enhanced by partially replacing commercial enzym... more Enzymatic saccharification of corn stover can be enhanced by partially replacing commercial enzymes with bacterial crude enzyme extracts. Thus, in this study, three bacteria (Bacillus sp. A0, Bacillus sp. CH20S1, and Exiguobacterium sp. AS2B) were cultured in a media with corn stover as the substrate to produce crude enzyme extract and saccharify corn stover. The cultural conditions were monitored and optimized to maximize CMCase and xylanase activity in the crude enzyme extracts. After 72 h of hydrolysis of corn stover with diluted crude enzymes (DCE) from the three strains, reducing sugars ranging from 48.2 to 71.7 mg g-1 were released from non-pretreated and pretreated corn stover. Furthermore, the maximum reducing sugars of 316 and 321 mg g-1 were observed when 12 and 4 FPU g-1 of commercial cellulase were added to the DCE of the CH20S1 strain, respectively. It was shown that an effective combination of bacterial DCE with commercial enzymes could achieve higher saccharification ...

Research paper thumbnail of Enzyme Production and Lignin Degradation by Four Basidiomycetous Fungi in Submerged Fermentation of Peat Containing Medium

International Journal of Biology, 2011

Biomass decomposing abilities of four basidiomycetous fungi (Pleurotus ostreatus sensu Cooke, Cor... more Biomass decomposing abilities of four basidiomycetous fungi (Pleurotus ostreatus sensu Cooke, Coriolus versicolor (L.) Quel., Tyromyces albidus (Schaeff.) Donk, and Trametes gallica Fr.) were studied using statically submerged media containing peat. The laccase, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), and total cellulase enzymatic profiles of the four fungi were assessed. The results revealed that laccase is the predominant ligninolytic enzyme secreted during the statically submerged fermentation process using peat as the substrate. T. gallica was the most active laccase producer with about 103 U/L at day 25. C. versicolor produced relatively higher levels of MnP than the other three basidiomycetous fungi (10 U/L). No significant LiP activity was detected in any of the four white rot fungi (WRF). Furthermore, the production of total cellulase by the four white rot fungi is low, which is beneficial to the selectivity of the bio-delignification. The Klason lignin content www.ccsenet.org/ijb

Research paper thumbnail of Effect of different carbon sources on cellulase production by Hypocrea jecorina (Trichoderma reesei) strains

International journal of biochemistry and molecular biology, 2011

The ascomycete Hypocrea jecorina, an industrial (hemi)cellulase producer, can efficiently degrade... more The ascomycete Hypocrea jecorina, an industrial (hemi)cellulase producer, can efficiently degrade plant polysaccharides. At present, the biology underlying cellulase hyperproduction of T. reesei, and the conditions for the enzyme induction, are not completely understood. In the current study, three different strains of T. reesei, including QM6a (wild-type), and mutants QM9414 and RUT-C30, were grown on 7 soluble and 7 insoluble carbon sources, with the later group including 4 pure polysaccharides and 3 lignocelluloses. Time course experiments showed that maximum cellulase activity of QM6a and QM9414 strains, for the majority of tested carbon sources, occurred at 120 hrs, while RUT-C30 had the greatest cellulase activity around 72 hrs. Maximum cellulase production was observed to be 0.035, 0.42 and 0.33 µmol glucose equivalents using microcrystalline celluloses for QM6a, QM9414, and RUTC-30, respectively. Increased cellulase production was positively correlated in QM9414 and negative...

Research paper thumbnail of Soluble human core 2 beta6-G1cNAc-transferase C2GnT1 requires its conserved Cys residues for full activity

Research paper thumbnail of Purification of crude glycerol using acidification: effects of acid types and product characterization

Purification of crude glycerol is essential for its applications for high-value products. In this... more Purification of crude glycerol is essential for its applications for high-value products. In this study, crude glycerol was purified by acidification using sulfuric, hydrochloric or phosphoric acid, and the results were compared. Phosphoric acid was found to be the best purifying agent among the others. Acidification of a biodiesel plant waste crude glycerol (containing approximately 13 wt% glycerol and 6 wt% ash) for a total processing time of 1 h, produced a purified product containing approximately 96 wt% glycerol, and 0.7 wt% ash. Effects of pH values on the purification efficiency were investigated. The crude glycerol and the purified products were extensively characterized.

Research paper thumbnail of Discovery, Modification and Production of T4 Lysozyme for Industrial and Medical Uses

International Journal of Biology, 2014

Lysozyme has attracted immense attention as an antimicrobial agent because of its ability to lyse... more Lysozyme has attracted immense attention as an antimicrobial agent because of its ability to lyse the bacterial cell wall. It is found in a wide variety of body fluids and in cells of the innate immune system. Lysozyme can act as muramidase or as a Cationic Antimicrobial Peptide (CAMP). Lysozyme has many applications in the medical and industrial fields. Based on enzyme nomenclature, lysozyme is classified as a glycosylase under the group hydrolases. This manuscript covers a fundamental review of lysozyme in terms of discovery, history, functions and various sources and types of lysozyme. The biological and molecular structure is discussed as well as notable bioengineering and protein modifications. Furthermore, the mechanisms of resistance to lysozyme in microorganisms have also been discussed. Lastly, different methods that have been developed for detecting and measuring the activity of lysozyme are outlined. Although, a recombinant lysozyme has not yet been produced, several studies have attempted to generate a modified lysozyme either for large-scale production or that which is more suitable for industrialization purposes.

Research paper thumbnail of The Human Trifunctional Enzyme ofde NovoPurine Biosynthesis: Heterologous Expression, Purification, and Preliminary Characterization

Protein Expression and Purification, 1998

Research paper thumbnail of Catalytic conversion of glycerol to oxygenated fuel additive in a continuous flow reactor: Process optimization

Fuel, 2014

h i g h l i g h t s A continuous flow process for synthesis of solketal from glycerol was optimiz... more h i g h l i g h t s A continuous flow process for synthesis of solketal from glycerol was optimized. A maximum yield of 94 ± 2% was obtained at optimum conditions. Presence of impurities (salt and water) demonstrated an adverse effect on the yield. The catalyst after 24 h on-stream use proved to be regenerable.

Research paper thumbnail of Thermodynamic and kinetic studies of a catalytic process to convert glycerol into solketal as an oxygenated fuel additive

Fuel, 2014

h i g h l i g h t s Thermodynamics and kinetics of glycerol ketalization were studied for the fir... more h i g h l i g h t s Thermodynamics and kinetics of glycerol ketalization were studied for the first time. External mass transfer resistance was completely eliminated above 400 rpm. Moisture content demonstrated an adverse effect on the yield of solketal. Kinetics of the reaction was modeled by Langmuir-Hinshelwood rate expression. The activation energy for the reaction was determined to be 55.6 kJ mol À1 .

Research paper thumbnail of Antibacterial activity of northern Ontario medicinal plant extracts

Canadian Journal of Plant Science, 2014

Hassan, H. M., Jiang, Z.-H., Asmussen, C., McDonald, E. and Qin, W. 2014. Antibacterial activity ... more Hassan, H. M., Jiang, Z.-H., Asmussen, C., McDonald, E. and Qin, W. 2014. Antibacterial activity of northern Ontario medicinal plant extracts. Can. J. Plant Sci. 94: 417–424. In the present study, the antibacterial activity (in vitro) of the leaf and/or flower crude extracts of Anaphalis margaritacea (L.) Benth & Hook.f., Grindelia squarrosa (Pursh) Dunal, Apocynum androsaemifolium L., Arctostaphylos uva-ursi (L.) Spreng, Cornus canadensis L. and Xanthium strumarium L. medicinal plants was analyzed through the hole-plate diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays against Escherichia coli, Aeromonas caviae, Paenibacillus alvei, Micrococcus luteus, Mycobacterium avium subsp. avium and Bacillus cereus bacteria. In addition, the time-kill dynamic processes of these extracts against A. caviae, B. cereus, P. alvei, and M. luteus bacteria were also tested. The leaf and flower extracts of Anap. margaritacea and G. squarrosa possess ...

Research paper thumbnail of Review: Northern Ontario medicinal plants

Canadian Journal of Plant Science, 2012

Hassan, H. M., Jiang, Z.-H., Syed, T. A. and Qin, W. 2012. Review: Northern Ontario medicinal pla... more Hassan, H. M., Jiang, Z.-H., Syed, T. A. and Qin, W. 2012. Review: Northern Ontario medicinal plants. Can. J. Plant Sci. 92: 815–828. The majority of scholarly investigations conducted in the 20th century have provided the incentive for establishing plants as sources of diverse phytochemicals. With infectious and cancerous diseases causing millions of mortalities worldwide, and the advent of resistant strains, the discovery of new antimicrobial and anticancer agents is crucial. Hence, included in this review is a novel list of 48 northern Ontario medicinal plants that may be sources of antifungal, antibacterial and/or anticancer phytochemicals. A total of two ferns and allied plants, two sedges and grasses, six trees, four shrubs, one vine and 33 herbs were identified. These plants were accumulated through interviews with native Elders and a survey of ethnobotanical literature on northern Canadian species of medicinal plants. We also present a critical review of their potential cons...

Research paper thumbnail of Soluble human core 2 β6-N-acetylglucosaminyltransferase C2GnT1 requires its conserved cysteine residues for full activity

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics, 2003

Research paper thumbnail of A new continuous-flow process for catalytic conversion of glycerol to oxygenated fuel additive: Catalyst screening

Research paper thumbnail of Newly Isolated and Characterized Bacteria with

Research paper thumbnail of Agave Biomass is Excellent for Production of Bioethanol and Xylitol Using Bacillus Strain 65S3 and Pseudomonas Strain CDS3

Journal of Biobased Materials and Bioenergy, 2014

Research paper thumbnail of The prospects of cellulase-producing bacteria for the bioconversion of lignocellulosic biomass

International journal of biological sciences, 2009

Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversi... more Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. However, the biorefining process remains economically unfeasible due to a lack of biocatalysts that can overcome costly hurdles such as cooling from high temperature, pumping of oxygen/stirring, and, neutralization from acidic or basic pH. The extreme environmental resistance of bacteria permits screening and isolation of novel cellulases to help overcome these challenges. Rapid, efficient cellulase screening techniques, using cellulase assays and metagenomic libraries, are a must. Rare cellulases with activities on soluble and crystalline cellulose have been isolated from strains of Paenibacillus and Bacillus and shown to have high thermostability and/or activity over a wide pH spectrum. While novel cellulases from strains like Cellulomonas flavigena and Terendinibacter turnerae, produce multifunctional cellulases with broader substrate utilization. These ...

Research paper thumbnail of Overexpression of D-xylose reductase (xyl1) gene and antisense inhibition of D-xylulokinase (xyiH) gene increase xylitol production in Trichoderma reesei

BioMed research international, 2014

T. reesei is an efficient cellulase producer and biomass degrader. To improve xylitol production ... more T. reesei is an efficient cellulase producer and biomass degrader. To improve xylitol production in Trichoderma reesei strains by genetic engineering, two approaches were used in this study. First, the presumptive D-xylulokinase gene in T. reesei (xyiH), which has high homology to known fungi D-xylulokinase genes, was silenced by transformation of T. reesei QM9414 strain with an antisense construct to create strain S6-2-2. The expression of the xyiH gene in the transformed strain S6-2-2 decreased at the mRNA level, and D-xylulokinase activity decreased after 48 h of incubation. This led to an increase in xylitol production from undetectable levels in wild-type T. reesei QM9414 to 8.6 mM in S6-2-2. The T. reesei Δxdh is a xylose dehydrogenase knockout strain with increased xylitol production compared to the wild-type T. reesei QM9414 (22.8 mM versus undetectable). The copy number of the xylose reductase gene (xyl1) in T. reesei Δxdh strain was increased by genetic engineering to crea...

Research paper thumbnail of Increased expression of β-glucosidase A in Clostridium thermocellum 27405 significantly increases cellulase activity

Bioengineered

β-glucosidase A (bglA) in Clostridium thermocellum 27405 was increased by expression from shuttle... more β-glucosidase A (bglA) in Clostridium thermocellum 27405 was increased by expression from shuttle vector pIBglA in attempts to increase cellulase activity and ethanol titer by lowering the end product inhibition of cellulase. Through a modified electrotransformation protocol C. thermocellum transformant (+MCbglA) harbouring pIBglA was produced. The β-glucosidase activity of +MCbglA was 2.3- and 1.6-fold greater than wild-type (WT) during late log and stationary phases of growth. Similarly, total cellulase activity of +MCbglA was shown to be 1.7-, 2.3- and 1.6-fold greater than WT during, log, late log and stationary phases of growth. However, there was no significant correlation found between increased cellulase activity and increased ethanol titers for +MCbglA compared with the WT. C. thermocellum has industrial potential for consolidated bioprocessing (CBP) to make a more cost effective production of biofuels; however, the hydrolysis rate of the strain is still hindered by end pro...

Research paper thumbnail of Characterization of some efficient cellulase producing bacteria isolated from paper mill sludges and organic fertilizers

International journal of biochemistry and molecular biology, 2011

The wide variety of bacteria in the environment permits screening for more efficient cellulases t... more The wide variety of bacteria in the environment permits screening for more efficient cellulases to help overcome current challenges in biofuel production. This study focuses on the isolation of efficient cellulase producing bacteria found in organic fertilizers and paper mill sludges which can be considered for use in large scale biorefining. Pure isolate cultures were screened for cellulase activity. Six isolates: S1, S2, S3, S4, E2, and E4, produced halos greater in diameter than the positive control (Cellulomonas xylanilytica), suggesting high cellulase activities. A portion of the 16S rDNA genes of cellulase positive isolates were amplified and sequenced, then BLASTed to determine likely genera. Phylogenetic analysis revealed genera belonging to two major Phyla of Gram positive bacteria: Firmicutes and Actinobacteria. All isolates were tested for the visible degradation of filter paper; only isolates E2 and E4 (Paenibacillus species) were observed to completely break down filter...