S. Mahadevan

Molecular Reproduction, Development & Genetics
Research Areas: 
Microbial genetics, physiology and evolution
Research Highlights: 

The primary focus of our research has been to understand the different survival strategies adopted by microorganisms in their natural habitats. In this context, the evolutionary significance of bacteria maintaining a set of genes that are apparently silent and uninducible has been examined using the beta-glucoside utilization (bgl) genes of Escherichia coli and related microorganisms as an experimental paradigm. We have recently demonstrated the involvement of the bgl operon in the regulation of an oligopeptide transporter oppA that allows the import of short peptides that can be used both as energy source as well as precursors, providing a growth advantage in stationary phase. Thus, modulation of the activity of genes that are maintained in a silent state offers a powerful mechanism for enhancing the metabolic capability of organisms under stress. The ability to hydrolyze aromatic beta-glucosides has been recently correlated with the capacity to avoid predation in the soil environment. The aglycones released during the hydrolysis are toxic to predators, conferring a chemical weapon against predators. Therefore, relief from predation in addition to the generation of metabolic energy provides a strong selective force for the retention of the bgl genes in the genome. The evolution of new metabolic functions by mutations in preexisting genetic systems has also been investigated with the chb and bglA genes of E. coli. These studies have integrated genetic, molecular and behavioural approaches to understand microbial physiology, ecology, and evolution.