Cloning and sequencing of biofilm-associated protein (bapA) gene and its occurrence in different serotypes of Salmonella.

Aims: Salmonella spp. has the capability to form biofilm on various surfaces. Biofilm-associated protein (bapA), a large surface protein has been shown to play a leading role in the development of biofilm in Salmonella. Objective of this study was to investigate the presence of bapA gene in different serotypes of Salmonella spp. and to characterize DNA fragment encoding bapA protein of Salmonella Enteritidis. Methods and Results: Sixty-seven Salmonella strains belonging to 34 serovars isolated from diverse sources in India were screened for the presence of bapA gene employing a primer designed for the purpose. All the strains yielded a positive amplification indicating that the bapA gene is well conserved in Salmonella spp. The amplified gene fragment of bapA was cloned in Escherichia coli (DH5 alpha) cells by using pGEM-T easy cloning vector. On partial sequence analysis, the product exhibited 667 base pairs, corresponding to 218 amino acids. Conclusions BapA gene was found to be highly conserved in Salmonella. Partial sequence analysis of this gene from a strain of Salm. Enteritidis revealed close association with serotypes of poultry origin and also with some other animal/zoonotic serotypes. Significance and Impact of the Study: BapA gene can be targeted for the genus-specific detection of this organism from different sources. Antigenic index of bapA protein indicates its protective and diagnostic potentials.