Isolation, Screening and Molecular Characterization of Exopolysaccharide Producing Moderately Halotolerant Bacteria from Various Coastal Sites of Gujarat

Abstract

The exopolysaccharides (EPSs) are natural polymers of carbohydrates and are excreted by some bacteria outside of their cell walls. The microbial EPS have several biotechnological applications viz. cosmetics, textiles, pharmaceuticals, agriculture, paints and petroleum industries. The wide range of applications and bioactive roles of EPS has triggered increased interest for search unusual and novel EPS.The bacteria from marine ecosystem are also known to secrete novel EPSs. In this context, the main objective of this research is isolation, screening of most potent culturable EPS producing halotolerant bacteria with novel EPS characteristics which can be used in uncommon applications related to the environment. All the bacterial isolates were isolated from coastal regions of Gujarat as it contains 1600 km long costal area, with wide microbial diversity and can serve as a source for promising EPS producers. 9 soil samples were collected from various coastal sites viz. Mundra, Jodiya, Dwarka, Somnath, Diu, Bhavnagar, Khambhat, Dumas and Umargam. Total 59 EPS producing bacterial isolates were obtained in Primary Screening. Based on the results of primary screening, potential morphologically diverse 9 isolates were selected for EPS production in liquid medium. The EPS production ranged from 22.3 to 33.5 mg/ml. The isolate VHP 34 gave best EPS production and was identified as Enterobacter cloacae by 16 s rRNA gene sequencing method. The isolate Enterobacter cloacae VHP-34 was able to grow 0-15% NaCl concentration, hence categorized as Moderately Halotolerant.