Nisin抗性嗜热链球菌的筛选

采用两倍稀释法在脱脂乳培养基和乳清培养基中测定了nisin对嗜热链球菌9的最小抑菌浓度(MIC)。在脱脂乳培养基中逐渐增加nisin的浓度，驯化嗜热链球菌9，直到其抗性达到300IU／ml。经生产性能鉴定和遗传性状实验，获得两株适宜做酸奶发酵剂的nisin抗性嗜热链球菌9.31和9．4。

Isolation of Nisin-resistant Streptococcus thermophilus

The MIC of nisin to Streptococcus thermophilus was determined by serial twofold dilutions in skim milk medium and whey medium. In skim milk medium, Streptococcus thermophilus 9 was tamed by gradually increasing the nisin concentration until its resistance reaching 300 IU of nisin per ml. The two nisin-resistant Streptococcus thermophilus strains 9.31 and 9.4, fit for two yogurt culture were gained and assayed by production performance identification and genetic stability test.