Evaluation of cellulase and xylanase production from Trichoderma harzianum using acid-treated rice straw as solid substrate

Abstract

Rice straw is an agricultural waste potentially producing cellulases and xylanases enzymes, which are important to industrials. The present study reports on the effect of the furan derivatives from the acid-treated rice straw on the production of cellulase and xylanase by Trichoderma harzianum. The content of furan derivatives in rice straw treated with hydrochloric acid, sulphuric acid, acetic acid and nitric acid was analyzed by HPLC. Hydrochloric acid-treated rice straw was found to contain the highest concentration of 5-hydroxymethylfurfural, 96.4 μg/g, but lower furfural content. The furan derivatives content of hydrochloric acid-treated rice straw with different number of times washing and enzymes production were studied by a 5-days solid state fermentation. The furan derivatives content did not show significant negative impact on the production of cellulase and xylanase. The highest cellulase and xylanase contents were found to be 12.7 U/g and 110.7 U/g respectively in 2-washes of hydrochloric acid-treated rice straw. A 10-days of time growth profile was conducted to evaluate the cellulase and xylanase production of hydrochloric acid-treated (2-washes) and untreated rice straw. The maximum cellulase production was 16.1 U/g at day 2 using hydrochloric acid-treated rice straw. However, the maximum xylanase activity (271.5 U/g) was found to produce at day 3 in untreated rice straw. The morphology of untreated, hydrochloric acid-treated (2-washes) and fermented rice straw was characterized using SEM and FTIR. The compositions of cellulose and hemicellulose were increased after acid-pre-treatment, and reducing sugars was increased after solid state fermentation. The production of cellulase in hydrochloric acid-treated rice straw is higher as compared to untreated rice straw, yet, xylanase production is more significant with untreated rice straw.