Cellulolytic Potential of Lysinibacillus fusiformis Strain WGI4 Isolated From White Grub Beetle Phyllophaga sp. (Coleoptera: Scarabaeidae) Larvae Gut

Thirteen cellulolytic bacteria were isolated, screened and characterized from the larval guts of grub beetle Phyllophaga sp. To delimit the growth of non-cellulolytic bacteria, the isolated bacteria were grown directly on selective medium containing Carboxymethyl cellulose (CMC) as sole carbon source. The potent cellulase producing isolate was further subjected to morphological, biochemical and molecular characterization. A gram positive, rod shaped motile isolate WGI4 showed maximum endonuclease (or CMCase) activity of 0.93 IU/ml and exonuclease (or FPase) activity of 1.8 IU/ml at temperature 37 °C and alkaline pH between 24 and 48 h of incubation. Based on 16S rRNA gene analysis the strain was found to be most closely related to Lysinibacillus sphaericus, L. cavernae, L. macroides (99.01%, 99.01%, 98.87% similarity, respectively) and identified as Lysinibacillus fusiformis. Further, the larvae gut was subjected to scanning electron microscopic study which revealed presence of abundant rod shaped bacteria firmly attached to the gut wall. To the best of our knowledge this is the first report of SEM study of white grub beetle Phyllophaga sp. larvae gut and isolation of a novel bacterial strain.