棒杆菌属包括许多生物技术物种,医学或兽医意义。该属的一个重要特征是其细胞包膜中存在霉菌酸,形成保护性外膜(菌膜)的基础。结核分枝杆菌的细胞包膜中的霉菌酸与毒力有关。在这项研究中,我们分析了140株棒状杆菌的基因组,包括126个不同物种的代表。超过50%的这些菌株是从人类或动物的临床材料中分离出来的,突出了该属内致病潜力的真实规模。从系统发育角度来看,这些物种非常多样化,已分为19组和30个单例菌株。我们发现大量的棒状杆菌缺乏FAS-I,即,没有从头脂肪酸生物合成的能力,必须从其栖息地获得脂肪酸;这似乎解释了某些物种众所周知的亲脂性表型。在大多数物种中,存在与霉菌酸的缩合和成熟相关的关键基因,与它们的物种描述中霉菌酸的报道一致。相反,据报道缺乏霉菌酸的物种缺乏这些关键基因。有趣的是,顺子棒状杆菌,据报道缺乏霉菌酸,似乎拥有霉菌酸生物合成所需的所有基因。我们建议,尽管基于霉菌酸的菌膜被广泛认为是免疫系统和化学疗法干预的目标,该结构在棒状杆菌中不是必需的,也不是动物宿主致病性或定殖的先决条件。
The genus Corynebacterium encompasses many species of biotechnological, medical or veterinary significance. An important characteristic of this genus is the presence of mycolic acids in their cell envelopes, which form the basis of a protective outer membrane (mycomembrane). Mycolic acids in the cell envelope of Mycobacterium tuberculosis have been associated with virulence. In this study, we have analysed the genomes of 140 corynebacterial strains, including representatives of 126 different species. More than 50% of these strains were isolated from clinical material from humans or animals, highlighting the true scale of pathogenic potential within the genus. Phylogenomically, these species are very diverse and have been organised into 19 groups and 30 singleton strains. We find that a substantial number of corynebacteria lack FAS-I, i.e., have no capability for de novo fatty acid biosynthesis and must obtain fatty acids from their habitat; this appears to explain the well-known lipophilic phenotype of some species. In most species, key genes associated with the condensation and maturation of mycolic acids are present, consistent with the reports of mycolic acids in their species descriptions. Conversely, species reported to lack mycolic acids lacked these key genes. Interestingly, Corynebacterium ciconiae, which is reported to lack mycolic acids, appears to possess all genes required for mycolic acid biosynthesis. We suggest that although a mycolic acid-based mycomembrane is widely considered to be the target for interventions by the immune system and chemotherapeutics, the structure is not essential in corynebacteria and is not a prerequisite for pathogenicity or colonisation of animal hosts.