Proteomic and metabolomic approach to rationalize the differential mosquito larvicidal toxicity in Bacillus sp. isolated from the mid-gut of Culex quinquefasciatus mosquito larvae.

From the distinct wild locations of the Mumbai (India), dead Culex mosquito larvae were collected. The mid-gut micro-flora of these dead mosquito larvae was isolated on three different media that were selective for only the Gram-positive bacteria. These bacteria were tested against the third instar stage of  Culex quinquefasciatus  larvae, cultured in the laboratory, for their larvicidal activity. After performing the toxicity assay four times in duplicates, the average statistical values showed four bacteria exhibiting differential toxicities. Identification of these strains was done by 16S rRNA sequencing and their respective surface morphologies were studied by scanning electron microscopy (SEM). The differential toxicities of the four identified Bacillus strains were rationalized by performing differential proteomics and metabolomics approach using LC-MS and these results were analyzed against customized mosquito larvicidal toxin database which was further compared with the in silico p-BLAST data of that respective Bacillus sp. from the NCBI database. The presence and significance of the various mosquitocidal toxins in the identified Bacillus sp. are elucidated. The present study also attempted to identify new bacterial species exhibiting mosquitocidal toxicities that have not been reported earlier.