Biological treatment of lignocellulosic biomass by Chaetomium globosporum: Process derivation and improved biogas production.

Chaetomium globosporum was isolated from aeolian soil samples collected from semi-arid locations in the state of Rajasthan, India. The efficiency of fungal strain for biological treatment of biomass to improve biogas yield was screened by estimating laccase enzyme activity under submerged fermentation system. Further, lignocellulosic biomass(s) wheat and pearl millet straw were subjected to biological treatment and subsequent increase in release of reducing sugar as compared to untreated straw was determined. Optimization of biological treatment conditions was accomplished by employing response surface methodology with Box Behnken design of experiments. Impact of three parameters (temperature, residence time, moisture content) was analyzed using three severity levels on output response of biological treatment in terms of released reducing sugar (g/L). Observed values were well fitted with second order polynomial equation (R = 0.91) and predicted outcomes were in agreement with experimental results. Optimized treatment conditions were: 36 °C, 31 days residence time and 81% moisture. A 2.9 fold increase in reducing sugar was released when substrates were treated under these conditions. Our research findings emphasize importance of optimizing biological treatment conditions to achieve high biogas yield when using wheat and pearl millet straw as feedstocks and similar treatment could be carried out for other lignocellulosic feedstocks.