EVALUATION OF CELLULASE PRODUCTION BY RUMEN BACTERIA USING LIGNOCELLULOSIC SUBSTRATES AS CARBON SOURCE

Abstract

The rumen is a special digestive vessel of ruminants, where digestion of cellulose and other plant polysaccharides occurs through microbial activities. On average, cellulose accounts for 50% of the dry weight of plant biomass. Cellulose and agricultural wastes were used as sole carbon sources for the production of cellulase by bacteria. This study focused on isolating and screening cellulase-producing rumen bacteria. The isolated rumen bacteria were identified using morphological and biochemical tests. The design of the research involved a laboratory based comparative study of the performance of bacterial species in terms of cellulase production and activity. Serially diluted sample was spread plated on Carboxy methyle cellulose enriched LB agar for screening cellulase producing bacteria. The bacterial isolates were grown on carboxymethyl cellulose agar plates at different pH, temperature, incubation period, carbon source and substrate concentration. Three selected isolates showed clear hydrolysis zone on agar plates containing Carboxy methyle cellulose agar after detection with Congo-red staining as cellulase-producing bacteria. The isolates were later on identified as Pseudomonas (HUG3b and HUS2a) and the other one as Aeromonas (HUC4b). Among the isolates, HUG4b produced the highest cellulase production (2.02 u/ml) at pH 6.0 and a temperature of 30°C after an incubation period of 8 hours at 2% wheat straw concentration. Among the selected growth substrates (sorghum, wheat straw and baggase), wheat straw resulted in the highest amount of cellulase. The bacterial species present in rumen have the potential for cellulase production. This study generally revealed that bacterial isolates with cellulase activity might be an important part of future research to build up effective cellulase producing system that can be employed in industrial applications.