Abstract:

The strain KLDS 1.0338 capable of producing a high yield of bacteriocin, an antimicrobial substance effective
against Staphylococcus aureus, was screened from 7 strains of lactic acid bacteria preserved in our laboratory by separation
and purification. By eliminating the interference of organic acid and hydrogen peroxide and by conducting protease
sensitivity tests, we confirmed the antimicrobial role of this bacteriocin. Based on morphological, physiological and
biochemical characteristics and 16S rDNA sequence analysis, the strain was identified as Lactobacillus casei ATCC 334.
This strain was used to produce cottage cheese and the changes in cheese quality during storage at 4 ℃ were examined. The
experimental group obtained from co-fermentation with L. casei was compared with the control group fermented without
using L. casei. In the experimental group, the antibacterial activity was significantly enhanced (P < 0.01), the pH value
decreased gradually, the shelf-life of cottage cheese was effectively extended while maintaining the original color, flavor,
texture and other sensory characteristics of products.

Key words: bacteriocin, isolation and screening, cottage cheese, shelf-life