Cellulomonas sp. Isolated from termite gut for saccharification and fermentation of agricultural biomass

Abstract

Biofuel is an important alternative source of fuel, as many countries are looking to decrease their dependence on fossil fuels. One of the critical steps in biofuel production is the conversion of lignocelluloses to fermentable sugars, and there is need for cheaper and more efficient enzymatic strategies. Consequently, lignocellulase genes from various organisms have been explored. Termites possess varied sets of efficient micro-scale lignocellulose degrading systems. In this study, bacteria that degraded cellulose and xylan were isolated from termite gastrointestinal tract. The isolate was identified as Cellulomonas sp. by 16S rRNA gene sequencing. The bacterial enzymes cellulase and xylanase showed the highest activity at 50 °C and pH 8.0. The agricultural substrates were hydrolyzed by cellulases and xylanases, and more sugar was released from corn stover (18.903+0.65 mM/L) than from rice straw or cotton stalk. After direct hydrolysis and fermentation of agricultural substrates, ethanol (0.425+0.035 g/L) and lactate (0.772+0.075 g/L) were the major end products. Thus, termite gut bacteria can efficiently hydrolyze hemicellulose and cellulose, and these bacteria also have the potential to convert these fermentable sugars into valuable secondary metabolites.