Influence of sex and geographical location on culturable midgut bacterial diversity of pink bollworm, Pectinophora gossypiella larvae and their enzyme production potential.

Gut microbes play a dynamic role in many metabolic and physiological activities in insects. Recent studies have shown the difference in the gut microbiota associated with both sex and geographical locations. Deciphering the gut microbiota hosted with respect to their function in an economic pest like pink bollworm, Pectinophora gossypiella, is essential to understand the relationship between insect and its gut microbiome. In the present study, culturable midgut bacteria were isolated from Bt cotton resistant P. gossypiella larvae (male and female) collected from different cotton growing regions across India. A total of 37 bacterial isolates, 21 from male and 16 from female were obtained and identified based on 16S rRNA gene sequence. All the isolates belonged to two major phyla, Proteobacteria and Firmicutes. Only three isolates, Enterococcus casseliflavus, Enterobacter hormaechei subsp. xiangfangensis and Bacillus cereus were common to both the sexes, while the rest were specific to each sex. The study also indicated a higher bacterial diversity in populations collected from two locations, Adilabad and Khandwa. All the isolates were screened for extracellular hydrolytic enzyme production, protease, amylase, cellulase, xylanase and chitinase. The results revealed that, among 37 bacterial isolates, 33, 7, 6 and 4 isolates exhibited protease, cellulase, chitinase and amylase activity, respectively. Maximum production of protease was noticed in Pantoea dispersa GM2 (0.39 ± 0.02 U/ml), amylase from B. cereus RF2 (0.17 ± 0.04 U/ml), cellulase from Burkholderia contaminans KhF1 (endoglucanase – 8.29 ± 1.60 U/ml; exoglucanase – 12.77 ± 1.5 U/ml; β-glucosidase – 10.01 ± 0.7 U/ml) and chitinase from E. hormaechei subsp. xiangfangensis AuF (87 ± 0.02 U/ml). The findings suggest that the gut bacterial community is influenced by both sex and geographical locations and the enzyme production are confined to specific locations. Further molecular studies would reveal the factors responsible for microbial community diversity and enzyme production.