Wang Hui, Shen Jiawei, Ma Kai, Zhu Chengfeng, Fang Mengcheng, Hou Xue, Zhang Shijie, Wang Wenhui, Xue Ting
School of Life Sciences, Anhui Agricultural University, Hefei, Anhui 230036, China.
Experimental Center of Clinical Research, The First Affiliated Hospital of Anhui University of Chinese Medicine, Hefei, Anhui 230012, China.
Food Res Int. 2022 Sep;159:111602. doi: 10.1016/j.foodres.2022.111602. Epub 2022 Jun 30.
Staphylococcus aureus (S. aureus) is a momentous factor affecting food safety. It can survive under long-term desiccation stress and contaminate foods that have intermediate to low water activities. However, the specific molecular mechanisms by which it survives and persists under low water activity stress are often overlooked. In this study, transcriptome analysis was applied to investigate the effect of desiccation stress on gene expression of S. aureus RMSA24, a food-borne S. aureus strain that was isolated from a raw milk sample. Results of transcriptome analysis showed that the mRNA levels of genes related to capsular polysaccharides (CPs) synthesis were significantly upregulated after desiccation treatment, which was further confirmed by real-time reverse transcription PCR assays. Furthermore, the results of colony count experiments demonstrated that the survival of CPs mutant was decreased compared with the wild type strain. And the biofilm formation ability of CPs mutant showed no difference compared with that of wild type according to biofilm formation assays. Those results indicated that CPs mutant decrease the resistance to desiccation in S. aureus RMSA24 via a biofilm-independent pathway. This study provides new evidence regarding the mechanisms of desiccation resistance of food-borne S. aureus and contributes to the prevention of food contamination caused by this bacterium.
金黄色葡萄球菌是影响食品安全的一个重要因素。它能在长期干燥胁迫下存活，并污染水分活度处于中低水平的食品。然而，其在低水分活度胁迫下存活和持续存在的具体分子机制常常被忽视。在本研究中，运用转录组分析来探究干燥胁迫对食源金黄色葡萄球菌菌株RMSA24基因表达的影响，该菌株是从一份生乳样品中分离得到的。转录组分析结果显示，干燥处理后，与荚膜多糖（CPs）合成相关的基因的mRNA水平显著上调，这通过实时逆转录PCR分析得到进一步证实。此外，菌落计数实验结果表明，与野生型菌株相比，CPs突变体的存活率降低。并且，根据生物膜形成分析，CPs突变体的生物膜形成能力与野生型相比没有差异。这些结果表明，CPs突变体通过不依赖生物膜的途径降低了金黄色葡萄球菌RMSA24对干燥的抗性。本研究为食源金黄色葡萄球菌的抗干燥机制提供了新证据，并有助于预防由该细菌引起的食品污染。
