嗜热链球菌在鲜奶发酵中的抗逆性研究

本研究旨在探讨嗜热链球菌(Streptococcus thermophilus)对低蛋白浓度、双氧水及抗生素等因素的抗逆性,为产品研发提供依据。试验采用添加9ppm双氧水和蛋白含量为2.3%的鲜奶作为试验组,正常无添加双氧水和蛋白含量为2.9%的鲜奶为对照组,测定菌株发酵时间和酸奶质构差异,评价菌株对低蛋白浓度和双氧水的耐受性;采用纸片琼脂扩散法(K-B法),以金黄色葡萄球菌ATCC25923为参比菌株,测试菌株对5大类(林可霉素类、β内酰胺类、氨基糖苷类、氟喹诺酮类及其他类)共8种抗生素的耐药性。结果显示,供试菌株对于低蛋白、双氧水和抗生素等条件的抗逆性存在较大差异,少量菌株表现出较好的抗逆性,所有菌株对林可霉素类、青霉素类和氯霉素类表现敏感。

The resistance study of streptococcus thermophilus in milk fermentation

This study aimed to the resistant study of Streptococcus thermophilus to the low protein concentration,hydrogen peroxide and antibiotic,as to providing the basis for products development.To evaluate the tolerances of strains in the low protein concentration and hydrogen peroxide,we chose milk with hydrogen peroxide of 9 ppm and protein content of 2.3% as the experimental group,compared to the control group of milk without hydrogen peroxide and the protein content of 2.9%,and tested the differences of fermentation time and texture.To study the resistance to antibiotics of tested strains,five categories of antibiotics (Lincomycin,penicillins,aminoglycosides,fluoroquinolones and others) witha total of eight antibiotics were used in the test.The strains were detected in an disk agar diffusion technique (K-B method),with Staphylococcus aureus ATCC25923 as reference strains.The results showed that the tested strains had a great performance difference in the conditions of low-protein,hydrogen peroxide and antibiotic.There are a few of strains to show good resistance,however,all strains performed sensitive to Lincomycin,penicillins and chloramphenicol.