关键词: 发酵酸乳；屎肠球菌；细菌素；抑菌

Abstract: A total of 308 strains suspected of being Lactobacillus were isolated from traditional fermented yoghurt collected from Hongyuan, Sichuan province, and were screened by 96-well plate method and agar well diffusion method. Among these strains, SC-Y112 was selected for its obvious antibacterial effect. It was identified as Enterococcus faecium by morphological observation, 16S rDNA and ropA housekeeping gene sequencing analysis, and physiological and biochemical tests. After removing the influence of organic acid and hydrogen peroxide, the fermentation supernatant of the strain still had considerable antibacterial activity. The antibacterial effect decreased and even disappeared after being treated with protease, which indicated that the antibacterial components in the fermentation supernatant were proteins. Further, the biological characteristics, genetic stability and bacteriostatic characteristics of the bacteriocin produced by the strain were investigated, which showed that the bacteriocin was produced at 6 h and reached the maximum at 12?h after inoculation; the bacteriocin production ability was relatively stable within 86 consecutive generations; the bacteriocin was stable under the condition of pH 3.0-7.0 and heat-treatment at 100 ℃ for 30 min. The bacteriocin had a wide antibacterial spectrum, especially against Listeria monocytogenes.

Key words: fermented yogurt; Enterococcus faecium; bacteriocin; inhibition