Significance of marine salt pans as imminent source of bioactive secondary metabolites

Abstract

The marine environment is an interesting source for research and development. The potential of the domain in the discovery of new microorganisms capable of producing novel and useful bioactive secondary metabolites remains largely unexplored. Solar salt pans are hypersaline ecosystems and thus extreme environments. They consist of a series of inter-linked enclosures with a discontinuously increasing salinity gradient, due to the evaporation of seawater. Salinities here vary from 3.5 to 350 psu. Besides the obvious high salt content in the salt pans, the other stress conditions also include high temperature and heavy solar radiations. The salinity in these ecological niches supports halotolerant and halophilic microorganisms. Such an environment imposes a selective pressure on the residing organisms and thus the organism may be compelled to produce metabolites to make its surrounding conducive for its survival. Many new species of microbes have been identified and reported from the salt pans. However research applications are still in infancy, considering the wealth of the novel species existing in salt pans, as most of these studies are based on culture methods. In India, major saltpans are located along the coastal regions of Gujarat, Tamil Nadu, Maharashtra, Karnataka, Orissa, West Bengal and Goa. Bioprospecting of microbes from salt pans in India is comparatively still unexplored though few reports are available from Indian salterns. Some of the products reported from salt pans around the world include bacteriorhodopsin; compatible solutes; enzymes (hydrolases and isomerases); and biopolymers (biosurfactants, exopolysaccharides, liposomes, poly (gamma-D-glutamic acid), lectins and bioplastics). However, as compared to other marine ecosystems, the least number of bioactive products have been isolated from marine salterns. Hence, salt pans are still unexplored potential environments giving a wide scope for research in finding novel bioactive secondary metabolites.