Rapid inactivation of Salmonella by a quaternized biopolymeric flocculant

We report the characteristics and biocidal properties of a biopolymeric flocculant produced by Klebsiella terrigena capable of flocculating Salmonella efficiently from water. In order to impart an antimicrobial function, the native biopolymer was quaternized and the trimethyl biopolymeric derivative (TMB) was analysed physically, chemically and for flocculating properties. The quaternized biopolymer was evaluated for antimicrobial effects against four strains of Salmonella namely, S. typhimurium ATCC 23564, MTCC 1251, MTCC 98 and S. typhi MTCC 733. TMB did not differ significantly (p < 0.05) in either chemical and physical properties or flocculating ability when compared to its native counterpart. TMB completely inactivated Salmonella (60 μg/mL, at ambient temperature) within 60 min of exposure. Cell injury and death were evidenced by rapid increase in electrical conductivity in the media and release of intracellular alkaline phosphatase and glucose-6-phosphate dehydrogenases indicating permeation of cells. Electron micrographs revealed grossly altered morphology suggesting damage to the cell membranes as a possible reason for inactivation. The results of this study suggest a potential application of the developed biocidal bioflocculant for water treatment.