Abstract：
Thamnolia subuliformis (Ehrh.) W. Culb is a species of lichen with edible and medicinal applications in China. Our previous studies demonstrated that the methanol extract of Thamnolia subuliformis (METS) exhibits broad antibacterial activity and stability against foodborne pathogens. This study aimed to investigate the antibacterial mechanism of METS against Staphylococcus aureus using nontargeted metabolomics, focusing on cell wall and membrane damage. The results revealed that the minimum inhibitory concentration (MIC) was 0.625 mg ml-1 and that METS had good biosafety at this concentration. METS caused significant damage to the cell wall and membrane integrity, based on both morphological observation by electron microscopy and the leakage of alkaline phosphatase, protein, and nucleic acid in the cell cultures. Treatment with METS at the MIC disrupted the lipid metabolism of S. aureus, causing a decrease in the metabolism of various phospholipids and sphingolipids in the cell membrane and an increase in the ratio of saturated fatty acids to unsaturated fatty acids. Moreover, it influenced intracellular amino acid and energy metabolism. These results shed light on the antibacterial mechanism of METS against S. aureus while also serving as a reference for the further development of natural antibacterial compounds derived from Thamnolia subuliformis.
摘要：
双甲无菌科（Ehrh。)W.库尔布。是一种在中国具有食用和药用用途的地衣。我们先前的研究表明，流形Thamnoliasuguleformis（METS）的甲醇提取物对食源性病原体具有广泛的抗菌活性和稳定性。本研究利用非靶向代谢组学研究METS对金黄色葡萄球菌的抗菌机制,关注细胞壁和细胞膜损伤。结果表明，METS的最小抑菌浓度（MIC）为0.625mg·mL-1，在该浓度下METS具有良好的生物安全性。METS对细胞壁和膜完整性造成了重大损害，基于电子显微镜的形态学观察和碱性磷酸酶的渗漏，蛋白质，和细胞培养物中的核酸。用MIC的METS处理破坏了金黄色葡萄球菌的脂质代谢，导致细胞膜中各种磷脂和鞘脂的代谢减少，饱和脂肪酸与不饱和脂肪酸的比例增加。此外，它影响细胞内氨基酸和能量代谢。这些结果阐明了METS对金黄色葡萄球菌的抗菌机制，同时也为进一步开发衍生自沙门菌的天然抗菌化合物提供了参考。
