Identification and screenging of bacteriocin-producing lactic acid bacteria

Three lactic acid bacterium were isolated from Hunan traditonal fermented meats, which exhibited strong inhibitory activity against Listeria monocytogenes 54002. After eliminating the interference factors such as the organic acids, hydrogen peroxides, the inhibitory activity still existed. But inhibitory activity was lost after treatment with trypsin and pepsin. Therefore, the inhibiotory substance could be classed as bacteriocin. The bacteriocin exhibited good thermal stability and its active pH range from 5¹0. The three bacteriocin-producing bacteria were identified on the base of physiological and biochemical characteristics and 16S rRNA gene sequence. The sequence fragments around 1600bp 16S ribosomal RNA were amplified from total DNA of the three isolated strains by PCR. The sequence was completed by the application of BLAST on the websites of NCBI and phylogenetic tree was drawn with MEGA5.0. According to the high homology of 16S rRNA sequence, the three bacteriocin-producing bacteria was identified as Enterococcus faecium.