Objective: Evaluation of Extracellular Polymeric Substance (EPS) induced heavy metal tolerance in Kocuria sp. BRI 36.Methods: Initially, the effect of different concentrations of glucose (1-10 %) on EPS production by BRI 36 was examined. At optimum glucose concentrations, EPS levels were measured by varying heavy metal concentrations (10-50 ppm) of Pb2+, Cd 2+and Cr3+. Maximum tolerable concentration (MTC) and survival percentage of BRI 36 were determined under conditions that support EPS synthesis. Comparative analysis of extracted crude EPS was performed by Fourier Transform Infrared Spectroscopy (FTIR) to establish functional groups involved in the metal interaction. Results: Kocuriasp. BRI 36 produced maximum EPS (1g/l) at 5% glucose. Increase in EPS production up to 89% (considering 1g/l as 100%) with an increase in concentrations of heavy metals up to 40 ppm. MTC levels of BRI 36 for heavy metals increased up to 700 ppm when it was cultivated in presence of 5% glucose indicating a major role of surface polymer in metal adsorption. The function of EPS as a protective cover was also evident from an increase in survival percentage of BRI 36 up to 39.4 at MTC. Comparative analysis of extracted crude EPS by FTIR revealed the involvement of O-H, C=O, and C-O-C groups in metal adsorptionConclusion: Antarctic oceanic isolate Kocuria sp. BRI 36 has an ability to produced EPS under stress conditions of heavy metals. Simultaneously, its MTC values increased due to increase in EPS levels. These observations suggest the possibility to develop gentle, environmentally safe and cost-effective method for heavy metal removal.
EXTRACELLULAR POLYMERIC SUBSTANCE (EPS) FROM KOCURIA SP. BRI 36: A KEY COMPONENT IN HEAVY METAL RESISTANCE