Statistical Optimization of Nutritional and Physical Parameters for Xylanase Production from Newly Isolated Aspergillus oryzae LC1 and Its Application in the Hydrolysis of Lignocellulosic Agro-Residues (original) (raw)
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Journal of Technology Innovations in Renewable Energy, 2012
Alkali pretreated rice straw was used as substrate for cellulase production by a locally isolated fungus Aspergillus fumigatus NITDGPKA3 under solid state fermentation. Critical process parameters such as incubation period, temperature, basal medium content and pH were statistically optimized for an enhanced cellulase and xylanase yield by response surface methodology. The design predicted an optimum yield of 3.1 IU/g dry substrate, 64.18 IU/g dry substrate and 1040.57 IU/g dry substrate for FPase, CMCase and xylanase respectively under the optimum conditions of incubation period of 90 h, temperature at 33 o C, initial basal medium content of 62% and initial pH 4. The experimental values under optimum conditions correlated well with the predicted results. Further, crude enzyme extract from Aspergillus fumigatus NITDGPKA3 was used for saccharification of pretreated rice straw and this released 189.50 mg/g of reducing sugar. This work was carried out in the
Brazilian Journal of Development, 2020
In order to optimize the production of xylanase from a new thermophilic strain of Aspergillus fumigatus (OI-1R-T), Plackett-Burman design (PBD) and central composite rotational design (CCRD) were performed. The response surface plots indicated a trend for increased xylanase biosynthesis with increasing concentrations of corn straw. The optimized xylanase activity was 530 U mL-1 in the presence of 6.5% (w/v) of the residual biomass, which was 11 times (1,157%) higher than that obtained with only the PBD (45.8 U mL-1). Interestingly, xylanase thermostability was maintained at 90% at 50 °C for 6 h. Enzymatic hydrolysis assays conducted for 96 h with 2 U mL-1 of xylanase and crude corn straw, pre-treated corn straw (hemicellulose) and xylan from beechwood, resulted in the net production of 3.89, 20.96 and 21.64 µmol mL-1 of reducing sugars, respectively. Thus, A. fumigatus xylanase was equally able to hydrolyzes hemicellulose from corn straw and xylan from beechwood. The present data indicate that the xylanase activity of A. fumigatus could be applied to the production of low molecular weight sugars for use by pentose-fermenting yeast for the production of fuels and chemicals, among other products.
Biomass Conversion and Biorefinery, 2020
Most of the lignocellulosic biomass residues are decomposed and transformed by a variety of microbes in the natural environment. The xylanase production from Aspergillus niger strain BG has been produced using wheat bran under solid-state fermentation (SSF). One factor at a time approach (OFAT) was used to optimize the effect of the incubation period, initial pH, moisture content, and cultivation temperature on the xylanase production. Furthermore, experiments were designed with a Box-Behnken design (BBD) on the same variables using response surface methodology (RSM). Analysis of variance (ANOVA) was carried out and the xylanase production was expressed with a mathematical equation depending on the factors. Maximum xylanase yield after OFAT approach and RSM optimization was significant with maximum values of 4008.25 ± 3.73 U/g of dry substrate (U/gds) and 5427.51 ± 4.4 U/gds which have been recorded respectively compared with the initial conditions (1899.02 ± 1.6 U/gds) after 7 days of fermentation. The effects of individual, interaction, and square terms on xylanase production were represented using the non-linear regression equations with significant R 2 and p values. The optimum conditions established by RSM method for the maximum xylanase production were obtained with a pH media of 2.5 at 37°C using wheat bran as 84% humidified substrate after 66 h of incubation, this conditions resulted in 65.01% increased level of the xylanase production than produced in the initial conditions. Xylanase production from Aspergillus niger strain BG using RSM is considered advantageous for bioconversion of the agriculture residues.
Xylanase production by a newly isolated Aspergillus terreus MTCC 8661 was optimized using palm fiber in solid state fermentation (SSF). Different fermentation parameters such as incubation temperature, moisture content, medium pH, particle size, incubation time, inoculum, xylose and sodium nitrate concentrations were investigated at the individual and interactive level by the Taguchi methodology. All selected fermentation parameters influenced xylanase production. Moisture content, incubation time and inoculum concentration were the major [∼85%] influential parameters on xylanase production at the individual level. At the interactive level, inoculum concentration was important and accounted for more than 50% of the severity index with particle size and incubation temperature. Xylanase production improved from 41,000 to 115,000 U/g indicating 227% improvement after optimization suggesting that this fungal strain, A. terreus MTCC 8661, has the commercial potential for hemicellulosic enzyme production.
For successful commercialization of biomass to ethanol process, the techno-economic hurdles have to be overcome. Complete substrate utilization is the key for making economics favorable. Existing enzyme preparations do not give high saccharification efficiency, thus, a broader suite of hydrolases is required. Xylanase supplementation in enzyme cocktail is an important strategy to increase sugar yields. In our study, hyperxylanolytic Aspergillus awamori F18 was used to produce xylanase. A. awamori F18 expressed high levels of xylanase during Solid state fermentation of corncob and also, Carboxy Methyl Cellulase (CMCase), filter paper activity (FP lyase) and β-glucosidase (524.43, 43.95, 8.64 and 29.81 IU mg -1 proteins respectively). A 10.6-12.5 fold concentration of these activities was achieved by single-step acetone precipitation. Supplementing concentrated xylanase to Accellerase ® 1500 resulted in 69.5% enhancement in sugars released after 72 h of saccharification of steam-pretr...
Bioprocess and Biosystems Engineering, 2012
The production of extracellular xylanase by a locally isolated strain of Aspergillus tubingensis JP-1 was studied under solid-state fermentation. Among the various agro residues used wheat straw was found to be the best for high yield of xylanase with poor cellulase production. The influence of various parameters such as initial pH, moisture, moistening agents, nitrogen sources, additives, surfactants and pretreatment of substrates were investigated. The production of the xylanase reached a peak in 8 days using untreated wheat straw with modified MS medium, pH 6.0 at 1:5 moisture level at 30°C. Under optimized conditions yield as high as 6,887 ± 16 U/g of untreated wheat straw was achieved. Crude xylanase was used for enzymatic saccharification of agro-residues like wheat straw, rice bran, wheat bran, sugarcane bagasse and industrial paper pulp. Dilute alkali (1 N NaOH) and acid (1 N H 2 SO 4) pretreatment were found to be beneficial for the efficient enzymatic hydrolysis of wheat straw. Dilute alkali and acid-pretreated wheat straw yielded 688 and 543 mg/g reducing sugar, respectively. Yield of 726 mg/g reducing sugar was obtained from paper pulp after 48 h of incubation.
Biochemical Engineering Journal, 2010
Xylanase production by Aspergillus foetidus MTCC 4898 was carried out under solid state fermentation using wheat bran and anaerobically treated distillery spent wash. Response surface methodology involving Box-Behnken design was employed for optimizing xylanase production. The interactions among various fermentation parameters viz. moisture to substrate ratio, inoculum size, initial pH, effluent concentration and incubation time were investigated and modeled. The predicted xylanase activity under optimized parameters was 8200-8400 U/g and validated xylanase activity was 8450 U/g with very poor cellulase activity. Crude xylanase was used for enzymatic saccharification of agroresidues like wheat straw, rice straw and corncobs. Dilute NaOH and ammonia pretreatments were found to be beneficial for the efficient enzymatic hydrolysis of all the three substrates. Dilute NaOH pretreated wheat straw, rice straw and corncobs yielded 4, 4.2, 4.6 g/l reducing sugars, respectively whereas ammonia treated wheat straw, rice straw and corncobs yielded 4.9, 4.7, 4.6 g/l reducing sugars, respectively. The hydrolyzates were analysed by HPTLC. Xylose was found to be the major end product with traces of glucose in the enzymatic hydrolyzates of all the substrates.
Bioscience Journal, 2016
This study reports the optimization of xylanase production under solid state fermentation (SSF) by a thermotolerant Aspergillus fumigatus strain (SCB4) isolated from sugarcane bagasse piles of Brazilian Cerrado. Different combinations of low-cost agricultural byproducts in SSF were evaluated: sugarcane bagasse and wheat bran (1:1), sugarcane bagasse and corn straw (1:1) and only sugarcane bagasse. The enzyme biosynthesis by SSF was carried out at different temperatures (40, 45, 50 and 55 o C). The maximum levels of xylanase activity were obtained after 24 h at 45 °C using a culture medium containing sugarcane bagasse and wheat bran (1:1). Under optimal conditions, the fungal culture produced 574 U g-1 of xylanase (units/g of dry substrate). The crude enzyme showed optimal activity at 60 °C and pH 4.5. It exhibited thermostability up to 55 °C, wide range of pH stability and tolerance to ethanol, xylose and glucose. The physicochemical properties shown by this enzyme are appropriate for its application in hydrolysis of lignocellulosic residues for ethanol production and other bioproducts.
Xylanolytic and cellulolytic potential of a soil isolate, Aspergillus fumigatus (MS16) was studied by growing it on a variety of lignocellulosics, purified cellulose and xylan supplemented media. It was noted that carboxymethyl cellulose, salicin and xylan induce the production of endoglucanase, β-glucosidase and xylanase, respectively. The study revealed that Aspergillus fumigatus (MS16) co-secretes xylanase and cellulase in the presence of xylan; the ratio of the two enzymes was influenced by the initial pH of the medium. The maximum titers of xylanase and cellulase were noted at initial pH of 5.0. Relatively higher titers of both the enzymes were obtained when the fungus was cultivated at 35 o C. Whereas, cellulase production was not detected when the fungus was cultivated at 40 o C. The volumetric productivity (Q p) of xylanase was much higher than cellulases. The organism produced 2-3 folds higher titers of xylanase when grown on lignocellulosic materials in submerged cultivation than under solid-state cultivation, suggesting a different pattern of enzyme production in presence and in absence of free water. The partial characterization of enzymes showed that xylanase from this organism has higher melting temperature than endoglucanase and β-glucosidase. The optimum temperature for activity was higher for xylanases than cellulases, whereas the optimum pH differed slightly i.e. in the range of 4.0-5.0. Enzyme preparation from this organism was loaded on some crude substrates and it showed that the enzyme preparation can be used to hydrolyze a variety of vegetable and agricultural waste materials.
Molecules, 2021
Plant biomass constitutes the main source of renewable carbon on the planet. Its valorization has traditionally been focused on the use of cellulose, although hemicellulose is the second most abundant group of polysaccharides on Earth. The main enzymes involved in plant biomass degradation are glycosyl hydrolases, and filamentous fungi are good producers of these enzymes. In this study, a new strain of Aspergillus niger was used for hemicellulase production under solid-state fermentation using wheat straw as single-carbon source. Physicochemical parameters for the production of an endoxylanase were optimized by using a One-Factor-at-a-Time (OFAT) approach and response surface methodology (RSM). Maximum xylanase yield after RSM optimization was increased 3-fold, and 1.41- fold purification was achieved after ultrafiltration and ion-exchange chromatography, with about 6.2% yield. The highest activity of the purified xylanase was observed at 50 °C and pH 6. The enzyme displayed high th...