Identification and characterization of chitinase-producing bacteria from gut of pleurostict scarab beetle grubs (Coleoptera: Scarabaeidae)

An investigation was conducted to isolate, identify and molecularly characterize the chitinase-producing bacterial isolates from the guts of four pleurostict scarab beetle larvae [one species belonging to subfamily Rutelinae ( Anomala bengalensis ) and three species belonging to subfamily Melolonthinae ( Brahmina coriacea, Holotrichia setticollis and Holotrichia longipennis )] through 16 S rRNA sequencing. A total of 74 chitinase-producing bacterial strains were isolated from different gut compartments of selected species; of which 20 bacterial isolates recorded a clear halo zone of ≥ 5 mm (diameter) around the bacterial colony indicating chitinase activity. These 20 chitinase-producing bacteria were selected and sequenced for the 16 S rRNA gene. Maximum chitinase-producing bacteria were isolated from the fermentation chamber of all the selected scarab beetle larvae. The chitinase-producing bacterial community was represented by only two phyla i.e., Firmicutes and Actinobacteria. Bacillus was the most dominant group with 17 isolates. In addition to this, the insecticidal properties of chitinase-producing bacterial isolates were evaluated against mustard aphid ( Lipaphis erysimi ). Maximum per cent mortality was recorded by Bacillus licheniformis strain CHG3FC1 i.e., 30.00 ± 10.00% 72 h after treatment. Thus, the experiment proved that scarab beetle larvae possess great potential to be a source of novel chitinolytic bacteria, that can be exploited for management of phyto-pathogenic fungi, bacteria and insect pests.