Molecular Biology and Epidemiology of Vibrio cholerae

Vibrio cholerae is autochthonous to the aquatic environment and hence monitoring this bacterium in water sources is important. We are interested in studying its molecular biology with respect to virulence profile and antibiotic resistance pattern. Serotyping results confirm that most of the strains screened so far belonged to non-O1/non-O139 group. Four novel allele/variant of tcpA in environmental toxigenic strains were reported. The studies carried out in our laboratory also revealed high frequency of multiple drug resistance in environmental isolates. The study revealed that the strains isolated from Alappuzha district were resistant to all major antibiotics administered to treat cholera and other diarrhoeal diseases. The emergence of such multidrug resistant strains in the environment is a serious concern in the context of public health. Hence study of molecular mechanisms involved in the drug resistance is very essential. Our group is interested in the role of plasmids, SXT constin and Class 1 integrons in conferring multiple drug resistance in environmental isolates of V. cholerae.

Search of novel bioactive molecules from Actinomycetes that interfere with quorum sensing in Vibrios

Virulent genes in V. cholerae are regulated by quorum sensing, a phenomenon by which bacteria monitor their cell population density through the extracellular accumulation of signaling molecules called autoinducers. Recently, single as well as multiple quorum sensing circuits of varying architecture have been identified in the Vibrios. Quorum sensing plays an important role in biofilm formation. Several studies have suggested that biofilms may be important for survival, virulence and stress resistance of Vibrio spp. in the environment. We are interested in V. cholerae biofilm inhibition, and potential biofilm inhibitors will be isolated from suitable bioresources and its mechanism of action will be explored. We are also interested in the up-regulation and down-regulation of various candidate genes during the process of biofilm inhibition. These studies should advance identification of new targets for inhibitors of bacterial biofilm development. Most antibiotics initially work extremely well, killing more than 99.9% of microbes they target. But through mutation and the selection pressure exerted by the antibiotic, a few bacterial cells inevitably manage to survive, repopulate the bacterial community, and flourish as antibiotic resistant strains.

Bioprospecting bacteria isolated from the Arctic

The permanently cold environments on the Earth’s surface have been successfully colonized by a group of extremophilic microorganisms that are known as psychrophiles (cold-loving). The ability to thrive at temperatures that are close to, or below the freezing point of water requires a vast array of adaptations to maintain the metabolic rates and sustained growth compatible with life in these stressed environmental conditions. Therefore, it is possible that psychrophiles produce cold-adapted enzymes, which exhibit high catalytic activities at low temperature, in order to adapt to a cold habitat. It is in this context we are exploring the potential of cold adapted bacteria for producing various enzymes such as β-galactosidases, proteases and lipases. Our lab is successful in the characterization of a crude β-galactosidase from a psychrotrophic Enterobacter sp. Future studies include identification of novel cold adapted genes, promoters/ expression systems and biofilm inhibitors from bacteria isolated from the Arctic and its molecular characterization.
Microbe-hunting expedition to the North Pole