冷冻对冷饮中大肠埃希菌亚致死性损伤的实验观察

Observation on the Sub-Fatal Damage of Freezing on the Colon Bacillus in Cold Beverages

目的在灭菌的冷饮中加入大肠埃希菌(8099),观察大肠埃希菌经冷冻(-20℃)后在3种培养基上的生长情况。方法将经过90 mim和(48±2)h冷冻后的大肠埃希菌用倾注法在胰化大豆琼脂(TSA),单倍乳糖胆盐培养基(以下简称单料)和双倍乳糖胆盐培养基(以下简称双料)上培养,进行菌落计数,并计算出单料,双料培养基上菌落数减少的百分比。结果大肠埃希菌在活菌浓度为10-3cfu/ml时冷冻后与TSA相比,单料上的菌落数减少51.2%,双料减少33.4%。大肠埃希菌在3种培养基上冷冻90 min和(48±2)h,菌落数差异无显著性。结论亚致死性损伤菌在TSA上能够生长,而在含胆盐的单料和双料上则菌落数明显减少。

[ Objective] Colon bacillus was put into sterilized cold beverages; observation was carried out on their growth on 3 kinds of culture media. [Methods] Colon bacillus that had been frozen forgo minutes and （48 ± 2） hours was poured onto TSA, haploid lactose bile salt culture （HC） and diploid lactose bile salt culture （DC） respectively; the colony counting was calculated. [Results] Compared with TSA, the colony counting （ the concentration of live colon bacillus was 10 - 3 cfu/mlon） on HC decreased by 51.2%, that on DC decreased by 33.4%. No significant difference was found in the colon counting under the condition of being frozen for 90 rain and （48 ± 2） hours. [ Conclusion] The sub- fatal damage bacteria can grow on TSA but the colony counting of which decreases obviously on HC and DC.