Abstract: SAU-2, a bacteriocin-producing strain, was screened out of 34 strains isolated from milk residue in West Sichuan plateau. The strain was identified as Enterococcus based on colonial morphology, physiological and biochemical characteristics and 16S rDNA sequence phylogenetic analysis. SAU-2 had no hemolytic activity. All the virulence factors of agg, gelE, cylM, cylB, cylA, esp, efaAfm, cpd, cob, ccf, cyILL, cyILS, fsrB and hyLEfm were negative. These results indicate that SAU-2 is safe. In addition, bacteriocin produced by SAU-2 could tolerate heat treatment at 121 ℃ for 20 min, and exhibited antibacterial activity at pH 2.0-12.0, but was sensitive to trypsin and proteinase K. It showed strong inhibitory effect on relative strains of SAU-2 and Gram-positive bacteria, and could also inhibit one strain of Pseudomonas aeruginosa and one strain of Rhodotorula glutinis, but had no inhibitory effect on other Gram-negative bacteria and fungi.

Key words: milk residue, Enterococcus, bacteriocin, virulence factors, characterization