Functional and physicochemical characterization of marine exopolysaccharide derived from the novel bacterium Algoriphagus sp. K5R and its application towards biomineralization of gold and silver

The widespread use of synthetic polymers in various industries has raised worldwide concerns regarding their ecological impact and effects on human health. As a result, biopolymers have emerged as a promising alternative. Among them, exopolysaccharides (EPSs) produced by microbes from terrestrial niches have been extensively studied. However, recent reports have indicated that microbes from marine environments can also produce unique EPSs that could serve as sustainable substitutes to meet the escalating demand for biopolymers. The present study, for the first time, reports EPS production from novel marine bacterium Algoriphagus sp. K5R for sustainable application development. Interestingly, physicochemical analyses suggest that EPS K5R is a high molecular weight (1190.63 kDa) heteropolysaccharide composed of galacturonic acid, glucose and mannose. To evaluate EPS production, growth and fermentation kinetics were performed, which revealed that it was a primary metabolite having a maximum production of 4.79 +/- 0.57 g L-1 with 2% (w/v) glucose. Moreover, EPS K5R exhibits exceptional functional properties, namely high water-holding capacity (720% +/- 80.29%) and oil-holding capacity (493.33% +/- 49.74% for coconut oil and 533.32% +/- 17.47% for olive oil), and non-Newtonian pseudo-plastic behavior which render it a promising candidate for application in the cosmetics and food industries. In fact, its anti-oxidant capabilities make it an ideal biological reducing agent for metal nanoparticle synthesis. Overall, this study highlights the potential of marine EPSs for a diverse array of industrial applications.