Yang Xu, Huang En, Yousef Ahmed E
Department of Food Science and Technology, The Ohio State University, Columbus, OH, United States.
Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
Microbiol Res. 2017 Jan;195:18-23. doi: 10.1016/j.micres.2016.11.002. Epub 2016 Nov 18.
Brevibacillin is a newly-discovered antimicrobial lipopeptide produced by Brevibacillus laterosporus OSY-I. It is active against Gram-positive bacteria, including antibiotic resistant strains. This research was initiated to investigate the mechanism of action of brevibacillin against an indicator strain, Staphylococcus aureus ATCC 6538. Results of the study proved that brevibacillin binds to lipoteichoic acid (LTA) on cell wall before interacting with cell membrane. Additionally, brevibacillin disrupts S. aureus cytoplasmic membrane by increasing its permeability, depolarization and potassium leakage. Therefore, cytoplasmic membrane serves as a major target for brevibacillin. Despite the presence of multiple sites on S. aureus cell envelope, scanning electron microscope observation didn't reveal evidence of cell lysis or any morphological defects in cells treated with brevibacillin. Based on the results of this study, we propose that the electrostatic interaction between the cationic brevibacillin and the anionic LTA helped the accumulation of the antimicrobial agent at cell surface; this was followed by translocation of the lipopeptide to the cytoplasmic membrane and disrupting its vital functions.
短芽孢杆菌素是一种新发现的由短芽孢杆菌OSY-I产生的抗微生物脂肽。它对革兰氏阳性菌具有活性，包括抗生素耐药菌株。本研究旨在探究短芽孢杆菌素对指示菌株金黄色葡萄球菌ATCC 6538的作用机制。研究结果证明，短芽孢杆菌素在与细胞膜相互作用之前先与细胞壁上的脂磷壁酸（LTA）结合。此外，短芽孢杆菌素通过增加金黄色葡萄球菌细胞质膜的通透性、去极化和钾离子泄漏来破坏其细胞质膜。因此，细胞质膜是短芽孢杆菌素的主要作用靶点。尽管金黄色葡萄球菌细胞包膜上存在多个作用位点，但扫描电子显微镜观察并未发现短芽孢杆菌素处理的细胞有细胞裂解或任何形态缺陷的证据。基于本研究结果，我们提出阳离子短芽孢杆菌素与阴离子LTA之间的静电相互作用有助于抗菌剂在细胞表面的积累；随后脂肽转移至细胞质膜并破坏其重要功能。
