Molecular and biochemical characterization of three bacterial symbionts of fruit fly, Bactrocera tau (Tephritidae: Diptera).

Characterization of three bacterial symbionts (BC1, BC2 and BC3) of fruit fly Bactrocera tau including morphological, biochemical and 16S rDNA (rrs gene) analysis was done to determine their taxonomic position. Morphological and biochemical characterization placed two bacteria (BC1, Klebsiella oxytoca and BC2, Pantoea agglomerans) into family Enterobacteriaceae and the third one (BC3, Staphylococcus sp.) into family Staphylococcaceae. 16S rDNA gene sequence comparison with the available NCBI database sequences further confirmed the characterizations of bacterial symbionts. Molecular phylogeny of Klebsiella oxytoca and Pantoea agglomerans closely related to the other free living enterobacterial members with 74 to 93% sequence homology (genetic distance 0.000 to 0.085); however, they showed only 74 to 87% similarity with other insect symbionts (genetic distance 0.090 to 0.121). Staphylococcus sp. showed 94% sequence homology with other members of family Staphylococcaceae with the genetic distance of 0.013. Population of these symbionts in adult fruit flies increased exponentially up to the 10th day of adult emergence and thereafter it became almost constant.