Although chitooligosaccharide (COS) has attracted the attention of some researchers due to its good solubility and broad-spectrum antibacterial activity, our study found that Staphylococcus aureus treated with low concentration of COS actively entered the viable-but-nonculturable (VBNC) state to resist this environmental stress. In this study, the transcriptome of VBNC-state S. aureus after COS treatment was analyzed by RNA-sequencing. Compared with the control group, pathway enrichment analysis showed that COS-treated S. aureus adopted a series of adaptive adjustment strategies for survival, including significant up-regulation of the differential genes' expression of such as ABC transporters (metI, tagG), Sec dependent transport pathway (secDF), peptidoglycan synthesis pathway (murG) and alteration of their physiological metabolic patterns, where ATP depletion played a key role in the formation of the VBNC-state S. aureus. Further, by using oxidative phosphorylation uncoupling agent to adjust the initial level of ATP in S. aureus, it was found that the reduction of intracellular ATP level could accelerate the formation of VBNC state. Overall, our results preliminarily elucidated the molecular mechanism of COS inducing the VBNC-state S. aureus. It provided an important theoretical reference for further achieving effective bacterial inactivation by COS.

尽管壳寡糖（COS）因其良好的溶解度和广谱抗菌活性而引起了一些研究者的关注，但我们的研究发现，低浓度COS处理的金黄色葡萄球菌主动进入活菌但不可培养（VBNC）状态以抵抗细菌。这种环境压力。在这项研究中，通过 RNA 测序分析了 COS 处理后 VBNC 状态金黄色葡萄球菌的转录组。与对照组相比，通路富集分析表明，COS处理的金黄色葡萄球菌采取了一系列适应性的生存调节策略，包括ABC转运蛋白（ metI 、 tagG ）、Sec等差异基因的表达显着上调。依赖性转运途径（ secDF ）、肽聚糖合成途径（ murG ）及其生理代谢模式的改变，其中ATP耗竭在VBNC状态金黄色葡萄球菌的形成中发挥了关键作用。进一步，通过使用氧化磷酸化解偶联剂调节金黄色葡萄球菌中ATP的初始水平，发现细胞内ATP水平的降低可以加速VBNC状态的形成。总体而言，我们的结果初步阐明了COS诱导VBNC状态金黄色葡萄球菌的分子机制。为进一步实现COS有效灭活细菌提供了重要的理论参考。