Enzymatic hydrolysis of lignocellulosic material using acidic cellulase and xylanase enzyme combination produced from Bacillus sp. strains and investigation of its usability in bioethanol production

In the study, cellulase and xylanase were produced from our own isolates, Bacillus sp strains, characterizations were performed, and the strains were molecularly identified. Using UV mutation, a yeast strain capable of fermenting six- and five-carbon sugar compounds has been developed. First, physical disintegration processes were applied to the cellulosic material, then weak acid and thermal pre-hydrolysis processes were applied, followed by enzymatic hydrolysis with different enzyme combinations, and ethanol was produced with mutant and recombinant yeast strains. The cellulase is optimally active at 60°C and pH 6.0 and producing strain was identified as Bacillus cereus. The xylanase is optimally active at 50°C and pH 6.0 and producing strain was identified as Bacillus subtilis. The developed mutant Saccharomyces cereviciae strain gained the ability to grow at 23% alcohol, 45% glucose and 35°C, and converted six- and five-carbon sugars into 86% alcohol compared to the recombinant ATCC 20618 strain. At the end of 96 hours of fermentation, 0.35 ml/g ethanol was obtained from the hydrolyzate obtained by using 5% substrate with ATCC 20618 strain, and 0.30 ml/g ethanol was obtained from our mutant strain.