A thermotolerant yeast from cow's rumen utilize lignocellulosic biomass from wheat straw for xylanase production and fermentation to ethanol

Abstract

For recycling agricultural wastes into the production of biofuel, fermentation technology is currently gaining more attention. Bioethanol is a widely used biofuel, however in industries, the fermentation of hemicellulosic feedstock is challenging since fermenting yeasts consume fewer xylose. To enhance the availability of renewable biofuels, Pioneers are keen to develop industrial strains that assimilate xylose along with glucose. In attempt to eliminate the obstacle, xylanolytic yeast with enhanced xylanase production were investigated. A thermotolerant yeast species, Pichia kudriavzevii strain SVMS2019, isolated from the cow's rumen was studied for xylanase production under solid-state fermentation with simultaneous degradation and saccharification of alkali-treated wheat straw biomass for the liberation of xylose sugars and then conversion into bioethanol. After statistical optimization through response surface methodology, the xylanase enzyme yield was enhanced up to 2.23 fold; the optimum conditions were 30 °C, pH 3.5, 72 h of incubation, and 1.5% of pretreated wheat straw to produce 273.02 IU/ml xylanase activity. The maximum of crude xylanase activity was shown at 50 °C and pH 6. The fermentation of xylose to ethanol by Pichia kudriavzevii SVMS2019, bioethanol was obtained at a maximum of about 3.18% at 42 °C in 72 h intervals. Through the novel source, we have obtained the strain that has a significant of hemicellulosic enzymatic saccharification with 2.23 fold increase in xylanase production yield through statistical optimization and produce bioethanol. While xylanolytic activity of yeast has been optimized, potential benefit of cellulosic hydrolytic activity also need to be studied to achieve the co-utilization of glucose and xylose.