Metal removal and reduction potential of an exopolysaccharide produced by Arctic psychrotrophic bacterium<em> Pseudomonas</em> sp. PAMC 28620

Abstract

An exopolysaccharide (EPS) was produced from psychrotrophic Arctic glacier fore-field soil bacterium <em>Pseudomonas</em> sp. PAMC 28620 using glycerol enriched medium, where the maximum productivity 7.24 ± 0.31 g L-1 with 8.74 ± 0.14 g L-1 of biomass was obtained after 168 h of fermentation. The EPS was purified and analysed by HPLC, GC-MS, FT-IR, 1H and 13C NMR. The EPS obtained from Arctic strain PAMC 28620 exhibits a distinctive structural composition and the constituent sugar monomers are rhamnose, galactose, glucose, fucose, mannose and ribose. The purified EPS had shown excellent flocculating and emulsification capacities with promising biotechnological and ecological implications. From the metal removal experiments, the EPS exhibited remarkable metal adsorption (99%) potential adopting the order Fe2+>Cu2+>Mg2+>Zn2+>Mn2+>Ca2+. FE-SEM combined with EDX analysis has shown that the metal ions were complexed or immobilized onto the EPS matrix and further reduced to nanoparticles (150-950 nm). This study is significant in terms of metal removal and reduction potential of Arctic bacterial EPS and the possible ecological roles of the EPS in Arctic environment.