The new exopolysaccharide produced by the probiotic strain L. reuteri B2: extraction, biological properties, and possible application for Ni 2+ ion removal from the contaminated water

As one of the most promising groups of microbes, lactic acid bacteria (LAB) can synthesize metabolites that can be used in different industries over the world, mainly in the pharmaceutical, food, and dairy industries. In this study, a novel exopolysaccharide was extracted and isolated from the probiotic strain Lactobacillus reuteri B2, and assessed on biological activity and its possible application as a biosorbent for the removal of Ni 2+ ions from contaminated water. New exopolysaccharide was characterized using FTIR, SEM, XRD, NMR, MALDI-TOF MS, and TGA/DTG analysis. Biological assays included antioxidative activity, cytotoxic assay, and adhesion assay of L. reuteri B2 to HT29 cells. Our hypothesis was that if this exopolysaccharide is nontoxic, it can be used as a novel biomaterial for the possible application of the removal of Ni 2+ ions from contaminated water. The scavenging effect of nontoxic exopolysaccharide was 76% at 2 mg/mL using ABTS assay, in biological assays, while the removal efficiency of nickel from the aqueous solution was 92.96% in biosorption study. According to these results, this exopolysaccharide can be considered a very promising biomaterial for potential application in different industries, from pharmacy to wastewater treatments. Graphical abstract