Pathogenicity, genetic aspects and characterization of vibrio species isolated from marine environment

Abstract

Vibrio is the gram negative bacteria possessing comma shape and it produces the copious diarrhea characteristic of enteric diseases by means of a potent enterotoxin, cholera toxin (CT). Vibrio spp. are facultative anaerobes that show positive result for oxidase test and are non-spore formers. Based upon the past results these Vibrio spp., 11 of which are known to be pathogenic for humans. Most of the pathogenic Vibrio strains are natural inhabitants of marine environment worldwide. As TCBS media contained a combination of alkaline pH and bile salts, it is a most preferable media for the isolation of Vibrio strains from the contaminants. In addition to antibiotic resistance, a high percentage of heavy metal resistance to the MIC tested was observed among isolated Vibrio spp. Certain pathogenic characteristics such as proteolysis, haemolysis, slime production and biofilm formation have been found among isolated Vibrio spp. PCR targeted to amplify trh, tdh, and toxRS gene were identified among isolates, which is responsible for the virulence factor. The isolate was grown under different stress conditions using metals (Hg, As, Zn, Cd), and the toxRS level of Arsenic is found to be at the highest level followed by Cadmium, Mercury and Zinc. Thus, in mercury and zinc contaminated environment, pathogenecity of Vibrio spp. is inhibited. In cadmium and arsenic contaminated environment, the pathogenicity appears to increase.