期刊
FOODS
卷 11, 期 7, 页码 -出版社
MDPI
DOI: 10.3390/foods11070996
关键词
Staphylococcus aureus; low temperature; oxidative stress; energy metabolism; cell structure; RNA-seq
资金
- National Natural Science Foundation of China [31601572]
- Natural Science Foundation of Henan Province [222300420455]
- Program for Science & Technology Innovation Talents in Universities of Henan Province [22HASTIT034]
- Department of Human Resources and Social Security of Henan Province
- Science and Technology Bureau of Zhengzhou City [2020CXZX0084]
This study investigates the survival mechanisms of different strains of Staphylococcus aureus at low temperatures. The findings reveal that the strains employ different strategies for survival, with strain BB-11 showing better cell membrane integrity, higher antioxidant activity, and enhanced energy metabolism compared to strain BA-26. Defense mechanisms also play a pivotal role in the response of strain BB-11 to stress.
In food processing, the temperature is usually reduced to limit bacterial reproduction and maintain food safety. However, Staphylococcus aureus can adapt to low temperatures by controlling gene expression and protein activity, although its survival strategies normally vary between different strains. The present study investigated the molecular mechanisms of S. aureus with different survival strategies in response to low temperatures (4 degrees C). The survival curve showed that strain BA-26 was inactivated by 6.0 logCFU/mL after 4 weeks of low-temperature treatment, while strain BB-11 only decreased by 1.8 logCFU/mL. Intracellular nucleic acid leakage, transmission electron microscopy, and confocal laser scanning microscopy analyses revealed better cell membrane integrity of strain BB-11 than that of strain BA-26 after low-temperature treatment. Regarding oxidative stress, the superoxide dismutase activity and the reduced glutathione content in BB-11 were higher than those in BA-26; thus, BB-11 contained less malondialdehyde than BA-26. RNA-seq showed a significantly upregulated expression of the fatty acid biosynthesis in membrane gene (fabG) in BB-11 compared with BA-26 because of the damaged cell membrane. Then, catalase (katA), reduced glutathione (grxC), and peroxidase (ahpC) were found to be significantly upregulated in BB-11, leading to an increase in the oxidative stress response, but BA-26-related genes were downregulated. NADH dehydrogenase (nadE) and alpha-glucosidase (malA) were upregulated in the cold-tolerant strain BB-11 but were downregulated in the cold-sensitive strain BA-26, suggesting that energy metabolism might play a role in S. aureus under low-temperature stress. Furthermore, defense mechanisms, such as those involving asp23, greA, and yafY, played a pivotal role in the response of BB-11 to stress. The study provided a new perspective for understanding the survival mechanism of S. aureus at low temperatures.
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