产细菌素乳酸菌的筛选及对农家干酪保质期的影响

从实验室保存的7 株乳酸菌中，经分离纯化，以金黄色葡萄球菌为指示菌，筛选获得1 株高产细菌素的菌株KLDS 1.0338，排除有机酸和过氧化氢的干扰以及蛋白酶敏感性实验，确定抑菌作用是由细菌素产生的。通过菌株形态学分析，生理生化及16S rDNA分析鉴定菌株KLDS 1.0338为干酪乳杆菌ATCC 334。进一步利用该菌株制作农家干酪，考察4 ℃贮藏期间干酪的变化，添加KLDS 1.0338干酪乳杆菌的实验组抑菌活性显著大于未添加KLDS 1.0338干酪乳杆菌组（P＜0.01），实验组的pH值下降平缓，可以有效延长农家干酪的货架期，并保持产品原有的色泽、风味、质构等感官特性。

Screening of Bacteriocin-Producing Lactic Acid Bacteria and Application in Extending Shelf-Life of Cottage Cheese

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.