Polysaccharide-based silver nanoparticles synthesized by Klebsiella oxytoca DSM 29614 cause DNA fragmentation in E-coli cells

Silver nanoparticles (AgNPs), embedded into a specific exopolysaccharide (EPS), were produced by Klebsiella oxytoca DSM 29614 by adding AgNO3 to the cultures during exponential growth phase. In particular, under aerobic or anaerobic conditions, two types of silver nanoparticles, named AgNPs-EPS(aer) and the AgNPs-EPS(anaer), were produced respectively. The effects on bacterial cells was demonstrated by using Escherichia coli K12 and Kocuria rhizophila ATCC 9341 (ex Micrococcus luteus) as Gram-negative and Gram-positive tester strains, respectively. The best antimicrobial activity was observed for AgNPs-EPS(aer), in terms of minimum inhibitory concentrations and minimum bactericidal concentr…