Isolation of cellulolytic bacteria and production of cellulase using different substrates

Abstract

Background and aim: Cellulase is an enzyme system that catalyzes the hydrolysis of cellulose into reducing sugars. Cellulases
are important industrial enzymes and have wide range of applications in industries such as food, brewery, wine, paper and pulp,
textile, feed, detergent, in agriculture and in the production of bioethanol. Methodology: In this work, bacteria were isolated from
cow dung and screened for the production of cellulase. Results: Highest enzyme production was shown by the isolate 10. Based
on morphological and biochemical reactions, the isolate was identified as Bacillus sp. Optimum pH and temperature for the growth
of the isolate was found to be 8.0 and 40°C respectively. Different agro- based wastes such as paddy straw, wheat bran; tamarind
seed powder and coconut shell powder were used as substrates for the production of cellulase by solid state fermentation. The
novel substrates- tamarind seed powder and coconut shell powder were found to be promising substrates for the production of
cellulase. Process optimization was done for different substrate concentrations, pH and temperatures. Maximal enzyme activity
with paddy straw and wheat bran was found at 20% substrate concentration, pH 7.0 and 40°C; with tamarind seed powder, at 25%
substrate concentration, pH 8.0 and 40°C; and with coconut shell powder, at 20% substrate concentration, pH 9.0 and 50°C. Partial
purification of the enzyme was carried out by ammonium sulfate precipitation followed by dialysis. The activity of the precipitated
enzyme was determined by gel diffusion method and maximum enzyme activity was recorded at 40% ammonium sulfate
concentration