Isolation and characterization of the culturable microbes associated with gut of adult dung beetle Onitis philemon (Fabricius)

Abstract

Experiments were done to identify and characterize the gut microbes of the adult dung beetle Onitis philemon for their ability to degrade cellulose, pectin and lignin. Ten bacterial isolates were isolated from the gut of O. philemon and identified using biochemical and 16S rDNA analysis. Cellulose degraders were identified as Acinetobacter baumannii (OPNF5.3), Citrobacter amalonaticus (OPYH5.15), Citrobacter freundii (OPNH10.3) Aeromonas caviae (OPNH8.2) and Acinetobacter sp. (OPMH8.8). The cellulolytic index ranged from 3.25 to 5.0 indicating robust CMCase production. Three isolates namely Aeromonas hydrophila (OPNH5.10), A. caviae (OPNH8.2) and C. freundii (OPNH10.3) were able to hydrolyze pectin and the maximum pectinase activity was also seen in the isolate C. freundii OPNH10.3 which was 1.08IU/ml. Citrobacter amalonaticus (OPYH5.15) and C. freundii (OPNH10.3) were also positive for lignin peroxidase indicating that they could degrade lignin. Citrobacter species could be playing an important role in the digestion of complex organic matter thus aiding in provision of nutrition to the dung beetle. The significance of identifying these isolates lies in possible application in organic waste decomposition.