Optimization of cellulose degrading bacteria isolated from rice rhizosphere for enhanced cellulase production and in situ residues decomposition

Abstract

Paddy residues burning is a common practice in the sub-continent to manage paddy waste,which results in deterioration of air quality in the surrounding areas and causes smog issue. In situ decomposition could be a viable option to manage this problem. About thirteen (13) cellulose degrading bacterial strains were selected and further screened based on various enzymatic activities. Finally, two strains (GW7 and HA 121) with highest enzymatic potential were selected for optimization of factors to enhance cellulase production. The selected bacterial strain GW7 was found positive for urease, protease, catalase, phosphates and cellulase activity. While HA121 strain was positive for urease, protease, phosphatase and cellulase enzymes. The strains GW7 and HA121 exhibited maximum cellulose activity of 23 U mL-1 and 19 U mL-1, respectively, at optimized conditions. The optimal conditions for GW7 were temperature 35°C, pH 8, 1.5% glucose and 0.5% urea concentration. However, for HA121 the highest cellulase activity was attained when 1% glucose and 0.5% urea as co-inducers were used at a temperature of 35 °C and pH 8 where cellulase enzyme production was found to be 19 U mL-1. The optimization of cellulolytic bacterial cultures for enhanced cellulase production has established its potential utilization for field application.