Variation in Particle Size, Moisture Content and Supplements for Improvement of Cotton Stalks’ Lignin Degradation by Phlebia radiata and Saccharification

Particle size, moisture content and media supplements were studied for delignification of cotton stalks by Phlebia radiata MTCC 2791 in solid-state fermentation. Highest lignin degradation of 31.02 ± 1.27% (w/w) with cellulose loss of 14.39 ± 0.53% (w/w) observed in cotton stalks having particle size 5 mm and 75% moisture content, after 40 days. Supplements Cu2+, Mn2+ and veratryl alcohol (VA) enhanced the lignolytic enzymes production and the lignin degradation. Supplements Mn2+ at 1 mM with lignin degradation 36.58 ± 0.28% (w/w), high selectivity value (SV) 2.81; Cu2+ at 0.5 mM with lignin degradation 31.75 ± 1.74% (w/w), SV 2.56; VA 0.5 mM with lignin degradation 33.96 ± 0.54% (w/w), SV 2.30 were optimal for pretreatment. The glucose yield increased to 113.22 ± 3.79 mg/g from 40 days pretreated cotton stalks with Mn2+ (1 mM) supplements, more than twofolds higher from untreated cotton stalks. Strong linear correlation of R2 = 0.956 between lignin degradation and glucose yield was observed.