Staphylococcus aureus infection poses a serious threat to public health, and antibiotic resistance has complicated the clinical treatment and limited the solutions available to solve this problem. Cold atmospheric plasma (CAP) is a promising strategy for microorganism inactivation. However, the mechanisms of microbial inactivation or resistance remain unclear. In this study, we treated S. aureus strains with a self-assembled CAP device and found that CAP can kill S. aureus in an exposure time-dependent manner. In addition, the liquid environment can influence the survival rate of S. aureus post-CAP treatment. The S. aureus cells can be completely inactivated in normal saline and phosphate-buffered saline but not in tryptic soy broth culture medium. Scanning and transmission electron microscopy revealed that the CAP-treated S. aureus cells maintained integrated morphological structures, similar to the wild-type strain. Importantly, the CAP-treated S. aureus cells exhibited a reduced pigment phenotype. Deletion of the staphyloxanthin biosynthetic genes crtM and crtN deprived the pigmentation ability of S. aureus Newman. Both the Newman-crtM and Newman-crtN mutants presented high sensitivity to CAP treatment, whereas Newman-crtO exhibited a survival rate comparable to wild-type Newman after CAP treatment. Our data demonstrated that the yellow pigment intermediates of the staphyloxanthin biosynthetic pathway are responsible for the protection of S. aureus from CAP inactivation. The key enzymes, such as CrtM and CrtN, of the golden staphyloxanthin biosynthetic pathway could be important targets for the design of novel sterilization strategies against S. aureus infections.

IMPORTANCE Staphylococcus aureus is an important pathogen that can be widely distributed in the community and clinical settings. The emergence of S. aureus with multiple-antibiotic resistance has complicated staphylococcal infection control. The development of alternative strategies with powerful bactericidal effects is urgently needed. Cold atmospheric plasma (CAP) is a promising strategy for microorganism inactivation. Nevertheless, the underlying mechanisms of microbial inactivation or resistance are not completely illustrated. In this study, we validated the bactericidal effects of CAP on S. aureus, including antibiotic-resistant strains. We also found that the golden staphyloxanthin, as well as its yellow pigment intermediates, protected S. aureus against CAP, and blocking the staphyloxanthin synthesis pathway at the early steps could strengthen the sensitivity of S. aureus to CAP treatment. These data provide insights into the germicidal mechanism of CAP from the aspect of bacteria and suggest new targets against S. aureus infections.

金黄色葡萄球菌感染严重威胁公众健康，而抗生素耐药性使临床治疗变得复杂，并限制了解决该问题的解决方案。大气冷等离子体（CAP）是微生物灭活的一种有前途的策略。但是，微生物灭活或耐药的机制仍不清楚。在这项研究中，我们用自组装的CAP设备处理了金黄色葡萄球菌菌株，发现CAP可以以时间依赖性的方式杀死金黄色葡萄球菌。另外，液体环境会影响金黄色葡萄球菌CAP治疗后的存活率。在金黄色葡萄球菌在生理盐水和磷酸盐缓冲盐水中，细胞可以完全失活，而在胰蛋白酶大豆肉汤培养基中则不能。扫描和透射电子显微镜显示，经CAP处理的金黄色葡萄球菌细胞保持整合的形态结构，类似于野生型菌株。重要的是，经CAP处理的金黄色葡萄球菌细胞表现出降低的色素表型。葡萄黄素生物合成基因crtM和crtN的缺失剥夺了金黄色葡萄球菌纽曼的色素沉着能力。两者Newman- CRTM和Newman- CRTN突变体呈现给CAP治疗高灵敏度，而Newman- CRTO在CAP治疗后，其生存率可与野生型纽曼媲美。我们的数据表明，葡萄黄素生物合成途径的黄色颜料中间体负责保护金黄色葡萄球菌免受CAP失活。金黄色葡萄黄素生物合成途径的关键酶（如CrtM和CrtN）可能是设计针对金黄色葡萄球菌感染的新型灭菌策略的重要目标。

重要事项 金黄色葡萄球菌是一种重要的病原体，可以广泛分布于社区和临床环境中。具有多重抗生素抗性的金黄色葡萄球菌的出现使葡萄球菌感染控制变得复杂。迫切需要开发具有强大杀菌作用的替代策略。大气冷等离子体（CAP）是微生物灭活的一种有前途的策略。然而，微生物灭活或耐药的潜在机制尚未完全阐明。在这项研究中，我们验证了CAP对金黄色葡萄球菌（包括抗药性菌株）的杀菌作用。我们还发现，金黄色葡萄黄素及其黄色颜料中间体受到保护金黄色葡萄球菌抗CAP，并在早期阻断葡萄黄素合成途径可以增强金黄色葡萄球菌对CAP治疗的敏感性。这些数据从细菌方面提供了对CAP杀菌机制的见识，并提出了针对金黄色葡萄球菌感染的新靶标。