Identification and characterization of hydrogen peroxide-generating Lactobacillus fermentum CS12-1

Lactic acid bacteria were isolated from silage, which produce high level of hydrogen peroxide in cell culture supernatant. The 16S rDNA sequeces of the isolate matched perfectly with that of Lactobacillus fermentum (99.9%), examined by a 16S rDNA gene sequence analysis and similarity search using the GenBank database, thus named L.fermentum CS12-1. L.fermentum CS 12-1 showed resistance to low pH and bile acid. The production of hydrogen peroxide by L. fermentum CS 12-1 was confirmed by catalase treatment and high-performance liquid chromatography L. fermentum CS 12-1 accumulated hydrogen peroxide in culture broth as cells grew, and the highest concentration of hydrogen peroxide reached 3.5 mM at the late stationary growth phase. The cell-free supernatant of L. fermentum CS 12-1 both before and after neutralization inhibited the growth of enterotoxigenic Escherichia coli K88 that causes diarrhea in piglets.