经辐照杀菌的无菌袋中耐辐照微生物分离与鉴定

对某番茄酱生产企业提供的辐照杀菌（辐照剂量≥15 kGy）的5 L无菌袋进行菌落计数、分离和鉴定。3 L无菌水反复漂洗，滤膜过滤后进行平板菌落计数，分离纯化后采用16S rDNA和dnaJ序列分析分别鉴定到属和种。结果表明，5 批次的样品中均有细菌检出，数量在5～132 CFU/袋，9 个典型菌落经过16S rDNA序列分析后，分别属6 个属，其中栖水菌属（Enhydrobacter）、不动杆菌属（Acinetobacter）和考克斯菌属（Kocuria）各1 株，微球菌属（Micrococcus）、微杆菌属（Microbacterium）和芽孢杆菌属（Bacillus）各2 株；dnaJ序列分析则将一株葡萄球菌C8-3鉴定到种-表皮葡萄球菌（Staphylococcus epidermidis）。辐照杀菌的无菌袋虽然微生物数量不高，但是依然残留了一些耐辐照的细菌，它们或多或少会给内装食品带来一定的食品安全隐患或影响食品保质期。

Isolation and Identification of Radiation Resistant Microorganisms Detected in Radiation Sterilize Pouches

Objective: To count, isolate and identify the radiation-resistant microorganisms present in 5 L sterile pouches provided by a tomato paste producer, sterilized by radiation at doses equal to or greater than 15 kGy. Methods: The pouches were washed repeatedly with 3 L of sterile water. The water was filtrated through a membrane and then spread on medium plates for counting microbial colonies. Finally, the microorganisms were isolated, purified and identified at the genus and species levels by analysis of their 16S rDNA sequences and dnaJ sequences. Results: All 5 batches of samples were found to contain detectable levels of bacteria, varying from 5 to 132 CFU/pouch. After analysis of the 16S rDNA sequences of 9 typical colonies, a total of 6 genera were found, namely, Enhydrobacter, Acinetobacter, Kocuria, Micrococcus, Microbacterium and Bacillus. Among these, strain C8-3 was identified as Staphylococcus epidermidis by dnaJ sequence analysis. Conclusion: Although the quantity of the radiation resistant bacteria in sterile pouches is sparse, some of them survive the radiation. Those bacteria may cause more or less effects on food safety and the stability of food quality.