Ma Xiao-Jing, Wang Tong, Zhang Hui-Min, Shao Jun-Qian, Jiang Mei, Wang Huai, Zhu Hui-Xia, Zhou Dong
School of Food and Biological Engineering, Hefei University of Technology, Hefei, China.
Ministry of Education, Engineering Research Center of Bio-Process, Hefei University of Technology, Hefei, China.
Front Microbiol. 2022 Sep 27;13:929932. doi: 10.3389/fmicb.2022.929932. eCollection 2022.
Crude sophorolipids (SLs) have been proven to perform varying degrees of inhibitory effects on different pathogenic bacteria. However, systematic comparative studies of pure lactonic sophorolipid (LSL) among different types of bacteria are few. In this study, the antibacterial effects and mechanisms of LSL on pathogenic bacteria of , sp., , and were investigated. Bacteriostatic circle, antibacterial rate, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of LSL on different pathogenic bacteria were measured. Then, the antibacterial mechanisms of LSL on and were explored using ultrastructural observation, cell membrane permeability analysis, intracellular ATP content determination, and extracellular UV absorption detection. With the minimum MIC and MBC values of 0.05 and 0.20 mg/ml, LSL exhibited the best inhibitory effect against , followed by . LSL showed no significant inhibitory effect on and sp. For both and , LSL achieved bacteriostatic and bactericidal effects by destroying the cell wall, increasing the permeability of the cell membrane and leading to the flow out of intracellular contents. However, the action mode and action intensity of LSL on the cell wall and membrane of these two bacteria were significantly different. LSL had a greater influence on the cell membrane of by "leaking," while it exhibited a stronger effect on the cell wall of by "blasting." These results contributed to a better understanding of the relationship between LSL and different bacterial cell structures, further suggesting the conclusion that LSL might be used for the targeted treatment of special pathogenic bacteria.
粗制槐糖脂（SLs）已被证明对不同病原菌具有不同程度的抑制作用。然而，关于纯内酯型槐糖脂（LSL）在不同类型细菌之间的系统比较研究较少。在本研究中，考察了LSL对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌和白色念珠菌等病原菌的抗菌作用及机制。测定了LSL对不同病原菌的抑菌圈、抗菌率、最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。然后，通过超微结构观察、细胞膜通透性分析、细胞内ATP含量测定和细胞外紫外线吸收检测，探讨了LSL对金黄色葡萄球菌和大肠杆菌的抗菌机制。LSL对金黄色葡萄球菌的最低MIC和MBC值分别为0.05和0.20 mg/ml，对其抑菌效果最佳，其次是大肠杆菌。LSL对枯草芽孢杆菌和白色念珠菌无明显抑制作用。对于金黄色葡萄球菌和大肠杆菌，LSL均通过破坏细胞壁、增加细胞膜通透性并导致细胞内容物外流而达到抑菌和杀菌效果。然而，LSL对这两种细菌细胞壁和细胞膜的作用方式和作用强度存在显著差异。LSL对金黄色葡萄球菌细胞膜的影响主要表现为“渗漏”，而对大肠杆菌细胞壁的影响则表现为“爆破”作用更强。这些结果有助于更好地理解LSL与不同细菌细胞结构之间的关系，进一步表明LSL可能用于特殊病原菌的靶向治疗。
