Optimization of growth determinants of a potent cellulolytic bacterium isolated from lignocellulosic biomass for enhancing biogas production

Abstract

Anaerobic digestion of lignocellulosic biomass is limited by inefficient hydrolysis of recalcitrant substrates, leading to low biogas yields where bacteria can be utilized successfully. In this study, we have chosen ten cellulose-degrading bacteria from active anaerobic slurry identified as Enterobacter ludwigii, Klebsiella pneumoniae, Pantoea agglomerans, Bacillus subtilis, Bacillus pumilus, Bacillus anthracis, Pseudomonas sp., Enterobacteriaceae bacterium Staphylococcus warneri, and Bacillus safensis; among them, E. ludwigii was found to be the most potent having an endoglucanase gene in the genome. The growth conditions of E. ludwigii were further optimized using Response Surface Methodology that designated 35 °C temperature, 6.5 pH, 5 % carboxymethylcellulose, 5 % yeast extract, 1 % ammonium nitrate as optimum growth conditions. The optimized growth module found to accelerate cellulase production at both transcription and translation level that in turn enhanced biogas production inside anaerobic digester as well. Finally, the growth-cellulase production relationship could be helpful in efficient industrial applications.