Isolation and Characterization of Cellulase Producing Bacteria from the Gut of Termites (Odontotermes and Heterotermes Species)

Aim: To identify, characterize and compare the cellulolytic potentials of strains isolated from the gut of Odontotermes and Heterotermes species.

Methodology: Termites were collected, identified, surface sterilized and used as source of cellulase producers. Enrichment of cellulose utilizers were done using liquid media containing carboxy methyl cellulose (CMC) as the sole source of carbon and their cellulolytic potentials were confirmed using congo red plate screening method. The isolates showing considerable zone of clearance were biochemically characterized. Three effective isolates were further identified by 16S rRNA gene sequence analysis. Growth curves of the strains were constructed under six different conditions (static and shaking at 25°C, 37°C and 45°C). Their cellulase activities- endoglucanase, FPase and β-glucosidase, assayed at 18 hours of incubation were compared under the above mentioned conditions.

Results: Five isolates showing significant zone of clearance were selected, out of which three belonged to Bacillus and one each to Staphylococcus and Enterobacter sp. The three Bacillus sp. which were dominant cellulase producers were found to belong to Bacillus cereus (strain HT from Heterotermes sp. and ODO1, ODO2 from Odontotermes sp.). All the isolates showed high growth at 37°C under shaker condition. Bacillus cereus ODO2 displayed a higher cellulolytic potential compared to strain HT and ODO1. The endoglucanase, FPase and β-glucosidase activities of ODO2 were 5.06 U/mg, 2.52 U/mg and 6.01 U/mg respectively. ODO2 showed optimum specific activity at 37°C in shaker condition, whereas ODO1 and HT preferred static at same temperature.

Conclusion: The strains obtained in the present study are potent cellulase producers and thus can find application in food, animal feed, textile, fuel and chemical industries. Optimization of media and genetic modification of the strains can further improve their efficiency. All the three isolates are promising in view of use in future.