Bioprocessing & Biotechniques Enhanced Saccharification of Steam-Pretreated Rice Straw by Commercial Cellulases Supplemented with Xylanase (original) (raw)
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Biotechnology Progress, 2011
Ethanol production from lignocellulosic raw materials includes a pretreatment step before enzymatic hydrolysis (EH). Pretreated substrates contain complex hemicelluloses in the solid fraction that can protect the cellulose from enzymatic attack. In addition, soluble xylooligomers are contained in the pretreated materials and may have an inhibitory effect on cellulase activity. In this context, several approaches for xylanase supplementation have been studied to increase EH yields. In this study, the whole slurry obtained after steam explosion pretreatment of wheat straw has been used as substrate. EH experiments were performed using commercial cellulase preparations supplemented with an endoxylanase (XlnC) from Aspergillus nidulans. Among different strategies of XlnC supplementation, the 24-h xylanase treatment before cellulase addition yielded an increase of 40.1 and 10.1% in glucose and xylose production, respectively. Different XlnC addition strategies were integrated in a simultaneous saccharification and cofermentation process (SSCF) using the xylose fermenting strain Saccharomyces cerevisiae F12. Ethanol production in SSCF was 28.4% higher when comparing to a simultaneous saccharification and fermentation process. V
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
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.
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.
International Journal of Environment, Agriculture and Biotechnology, 2020
Sugarcane straw (SS) was used in an economic biosystem to evaluate the production of xylanases and cellulases in submerged fermentation (SmF) by axenic and mixed mode from Trichoderma and Aspergillus species. T. reesei QM9414 axenic culture reached the highest xylanase production (90.2 U/mL) and 0.5 FPU/mL of cellulase activity. The evaluation of agro-industrial residues on fibrolytic enzymes production was performed by a D-optimal design, and revealed the best supplementation of 100% SS, while wheat bran and citric pulp showed lower inductive effects on enzymes production. Also, the scale-up in a stirred tank showed the same yield production profile (xylanase ~ 90 U/mL and celullase 0.6 FPU/mL). Xylanase was characterized by an optimum pH of 5-6 and temperature at 50 ºC, and thermal stability was below 50 ºC. The ion Mn2+ (5 and 10 mM) had a stimulatory effect on xylanase activity. The biobleaching application showed that 30 U/g of xylanases during 15 min decreased Kappa number in 9.37. These results indicate SS as an alternative substrate for fungi fibrolytic enzymes production and the xylanase with low cellulase extract as a potential biobleaching application.
2017
editor@tjprc.org SACCHARIFICATION OF ALKALINE TREATED RICE STRAW BY SUBSEQUENTLY HYDROLYSIS OF XYLANOLYTIC-CELLULOLYTIC ENZYMES FOR XYLOOLIGOSACCHARIDES AND GLUCOSE PRODUCTION KANOK WONGRATPANYA , JUNJARUS SERMSATHANASWADI , THIDARAT NIMCHUA , RATTIYA WAEONUKUL , PATTHRA PASON, CHAKRIT TACHAAPAIKOON , AKIHIKO KOSUGI 7 & KHANOK RATANAKHANOKCHAI 8 School of Bioresources and Technology, King Mongkut’ s University of Technology Thonburi, Bangkuntien Campus , Bangkok, Thailand Department of Chemical Technology, Faculty of Scienc e and Technology, Suan Dusit Rajabhat University, Bangkok, Thailand Enzyme Technology Laboratory, Bioresources Technolo gy Unit, National Center for Genetic Engineering and Biotechnology, Biotec, Thailand Science Park, Pathu mthani, Thailand Pilot Plant Development and Training Institute, Kin g Mongkut’s University of Technology Thonburi (Bangkuntien Campus), Bangkok, Thailand Biological Resources and Post-Harvest Division, Jap an International Research Center fo...
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.
Bioresources, 2017
Xylanase is a key enzyme in the conversion of lignocellulosic biomass into various oligosaccharides and simpler monomeric units through the hydrolysis of hemicellulose. Rice straw is readily available around the world and is a rich source of hemicellulose. Recently, there has been growing interest in the exploitation of rice straw as a low-cost substrate for the production of hemicellulolytic enzyme, i.e., xylanase. This study aimed to optimize the nutritional components (rice straw, magnesium sulphate, and calcium chloride concentrations) and physical parameters (temperature and pH) for xylanase production with a newly isolated Aspergillus oryzae LC1 under submerged fermentation using central composite design based response surface methodology. The optimum media constituents were 1% rice straw (w/v), 1.0 g/L calcium chloride, and 0.3 g/L magnesium sulphate, and the optimum physical parameters were pH 5 and 25 °C. The statistical design showed increased xylanase production with a ma...
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.
Energy & Fuels, 2014
Among the three Aspergillus spp. (A. niger, A. oryzae, and A. f umigatus) screened for cellulolytic enzyme production potential, A. niger produced cellulolytic enzyme in relatively higher concentrations than the other two isolates. Enzyme produced by all three isolates was optimally active at pH 5.0. Cellulases from A. niger and A. f umigatus were optimally active at 55°C, while the enzyme from A. oryzae showed optimum activity at 50°C. Cellulase from A. niger and A. f umigatus retained more than 80 and 70% activity, respectively, while cellulase from A. oryzae could retain only 20% activity at 55°C after 12 h. Cellulase from A. niger exhibited better stability at higher temperatures than the enzyme from the other two Aspergillus spp., showing half-life (t 1/2) of about 5 and 3 h at 70 and 80°C, respectively. Zymogram revealed multiple forms of endoglucanase, cellobiohydrolase, and β-glucosidase with molecular mass ranging between 28 and 154 kDa for cellulase from all three isolates. Hydrolysis of rice straw at 12.5% (w/v) with crude cellulase from A. niger HO resulted in fermentable sugar concentration and productivity of 66.2 g L −1 and 2.75 g L −1 h −1 , respectively, showing potential for the reported enzyme in biofuel industry.