Optimization of submerged cultivation parameters for a novel biological pretreatment of rice straw to enhance enzymatic hydrolysis

Abstract

Statistical optimization of submerged cultivation parameters was carried out by Taguchi orthogonal array design for delignification of rice straw using a novel alkalophilic fungus MVI.2011. Parameters such as media composition, pH, temperature, inoculum volume, biomass volume and incubation time were optimized in this study. The objective was to maximize the release of glucose (% of saccharification) at the end of 8 h enzymatic hydrolysis. Incubation time and concentration of peptone in the cultivation media, with P‐values 0.027 and 0.041, respectively, were the most significant factors affecting the delignification reaction. Optimal run gave percentage of saccharification of 14.18 ± 1.13% (g g−1) analogous to an increase of 1.96‐fold in comparison with untreated rice straw (7.23 ± 0.04% [g g−1]). The reaction was scaled up to delignify 120 g rice straw in a 5‐L fermenter, the % saccharification of which was 13.5 ± 0.68% (g g−1), equivalent to an increase of 1.87‐fold when compared to untreated straw. Fungal pretreatment with MVI.2011 exhibited exemplary hydrolysis rate and demanded less than a week for delignification. The study reports for the first time, a biological pretreatment technique that takes only 6 days. This method can be extended to the pretreatment of other lignocelluloses. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13020, 2019