Variation in Particle Size, Moisture Content and Supplements for Improvement of Cotton Stalks’ Lignin Degradation by <i>Phlebia radiata</i> 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.