Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
FEMS Microbiol Lett. 2010 Feb;303(1):33-40. doi: 10.1111/j.1574-6968.2009.01857.x. Epub 2009 Nov 17.
Persisters are a small population of slowly growing or nongrowing bacteria that are phenotypically resistant to antibiotics, but the mechanisms involved are not well understood. The aim of this study is to determine new mechanisms underlying antibiotic-tolerant persisters. The Escherichia coli deletion mutant library was screened to identify mutants that had a defect in persister survival after exposure to ampicillin for 24 h or 5 days. The identified mutants and the parent strain were subjected to minimum inhibitory concentration (MIC) and minimum bactericidal tests and antibiotic or stress conditions in exposure assays. sucB and ubiF mutants deficient in energy production were identified from the mutant screens to have defective persister survival as demonstrated by higher susceptibility to various antibiotics, including ampicillin, norfloxacin, tetracycline and gentamicin, and different stresses such as oxidative stress, acid pH and weak acid compared with the parent strain. In addition, both sucB and ubiF had a twofold lower MIC than the parent strain. The above sucB and ubiF mutant phenotypes could be complemented by their respective functional genes. Defective energy production through mutations in sucB and ubiF affects persister survival and could serve as new drug targets for persister bacteria.
持留菌是一小部分生长缓慢或不生长的细菌，它们在表型上对抗生素具有抗性，但涉及的机制尚不清楚。本研究旨在确定与抗生素耐受持留菌相关的新机制。筛选了大肠杆菌缺失突变体文库，以鉴定在暴露于氨苄青霉素 24 小时或 5 天后，在持留菌存活方面存在缺陷的突变体。对鉴定出的突变体及其亲本菌株进行最低抑菌浓度（MIC）和最小杀菌试验，以及在暴露试验中进行抗生素或应激条件试验。从突变体筛选中鉴定出能量产生缺陷的 sucB 和 ubiF 突变体，表现为对各种抗生素（包括氨苄青霉素、诺氟沙星、四环素和庆大霉素）和不同应激（如氧化应激、酸性 pH 和弱酸）的敏感性增加，与亲本菌株相比，持留菌的存活能力降低。此外，sucB 和 ubiF 的 MIC 均比亲本菌株低两倍。上述 sucB 和 ubiF 突变体表型可以通过其各自的功能基因来互补。通过 sucB 和 ubiF 突变导致能量产生缺陷会影响持留菌的存活，这可能成为持留菌的新药物靶点。
