This study aimed to evaluate the fate of Listeria monocytogenes in water microcosm and rainbow trout fillet under salinity stress of 0% and 30% NaCl at refrigerator temperature (4 ± 2 ℃). Bacterial culturability was studied by standard culture and colony count method. Reverse transcription-PCR (RT-PCR) of 16 S rRNA gene was used to detect viability of non-culturable bacteria. Also, the qualitative expression of pathogenic genes (hly and inlA) was studied using RT-PCR. The results showed that bacteria in water microcosm lost their culturability at 13 days under 0% salinity (starvation or distilled water) and at 27 days under 30% salinity; however, bacteria in rainbow trout fillet remained culturable under 0% and 30% NaCl. RT-PCR of 16 S rRNA gene was positive for all treatments during the period of this study, indicating the entering of L. monocytogenes into the viable but non-culturable state in water microcosm under 0% and 30% NaCl. Also, viable but non-culturable L. monocytogenes retained the expression of hly and inlA genes. So, it could be concluded that L. monocytogenes in viable but non-culturable state can cause serious health problems and further investigation is necessary to elucidate the effects of other processing and storage conditions (light, dark, smoking, etc.) on behavior of L. monocytogenes in smoked and salted fish.

中文翻译：

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鱼肉中单核细胞增生李斯特菌存活但不可培养状态下的毒力基因表达

本研究旨在评估在冰箱温度（4±2 ℃）下，0% 和 30% NaCl 盐度胁迫下水体和虹鳟鱼片中单核细胞增生李斯特菌的去向。通过标准培养和菌落计数方法研究细菌可培养性。16 S rRNA 基因的逆转录-PCR (RT-PCR) 用于检测不可培养细菌的活力。此外，还使用 ​​RT-PCR 研究了致病基因（hly 和 inlA）的定性表达。结果表明，水体微观世界中的细菌在0%盐度（饥饿或蒸馏水）下13天和30%盐度下27天失去可培养性；然而，虹鳟鱼片中的细菌在 0% 和 30% NaCl 下仍可培养。本研究期间所有处理的16 S rRNA基因RT-PCR均为阳性，表明L. 在 0% 和 30% NaCl 的水微观世界中，单核细胞增生李斯特氏菌转化为有活力但不可培养的状态。此外，有活力但不可培养的单核细胞增生李斯特菌保留了 hly 和 inlA 基因的表达。因此，可以得出结论，处于存活但不可培养状态的单核细胞增生李斯特氏菌会导致严重的健康问题，有必要进一步调查以阐明其他加工和储存条件（光照、黑暗、吸烟等）对李斯特菌行为的影响。熏鱼和咸鱼中的单核细胞增生李斯特氏菌。