Bacteriocinogenic potential and virulence traits of and isolated from human milk.

BACKGROUND AND OBJECTIVES

Human milk is a continuous supply of Lactic Acid bacteria (LAB), including enterococci with probiotic potentials. The aim of this study was to analyze two species, isolated from human milk for their probiotic potential, bacteriocin producing ability and virulence traits.

MATERIALS AND METHODS

TA0033 and TA102 were tested for acid and bile tolerance, survival in simulated gastric and intestinal conditions. The antibacterial spectrum of the isolates was tested by agar well diffusion assay. The antagonistic agent was characterized by physico-chemical methods. The enterocin structural genes, virulence determinants, vancomycin resistance and biogenic amine genes, such as , , , and were also determined.

RESULTS

The tested isolates survived acidic conditions, high bile salt (1%), simulated gastric and intestinal conditions. The culture supernatant fluids of the two isolates inhibited the growth of , , , , and . The antagonistic activity was lost in the presence of proteolytic enzymes but tolerated the action of catalase, lysozyme and lipase. In contrast to enterocin TA102, enterocin TA0033 possessed bactericidal mode of action. Bacteriocin structural genes, and were present in the genome of the two isolates, while TA102 additionally harboured and genes. The phenotypic and genotypic virulence assessment studies indicated hyaluronidase () production and vancomycin resistance in TA102 while, none of the isolates harboured the biogenic amine genes.

CONCLUSION

The presence of virulence genes in TA102 calls for careful monitoring of isolates for their safety parameters.