Seattle Biomedical Research Institute, Seattle, Washington, USA.
J Bacteriol. 2012 Feb;194(3):715-21. doi: 10.1128/JB.06304-11. Epub 2011 Nov 28.
Infections caused by biofilms are abundant and highly persistent, displaying phenotypic resistance to high concentrations of antimicrobials and modulating host immune systems. Tuberculosis (TB), caused by Mycobacterium tuberculosis, shares these qualities with biofilm infections. To identify genetic determinants of biofilm formation in M. tuberculosis, we performed a small-scale transposon screen using an in vitro pellicle biofilm assay. We identified five M. tuberculosis mutants that were reproducibly attenuated for biofilm production relative to that of the parent strain H37Rv. One of the most attenuated mutants is interrupted in pks1, a polyketide synthase gene. When fused with pks15, as in some M. tuberculosis isolates, pks1 contributes to synthesis of the immunomodulatory phenolic glycolipids (PGLs). However, in strains such as H37Rv with split pks15 and pks1 loci, PGL is not produced and pks1 has no previously defined role. We showed that pks1 complementation restores biofilm production independently of the known role of pks1 in PGL synthesis. We also assessed the relationship among biofilm formation, the pks15/1 genotype, and M. tuberculosis phylogeography. A global survey of M. tuberculosis clinical isolates revealed surprising sequence variability in the pks15/1 locus and substantial variation in biofilm phenotypes. Our studies identify novel M. tuberculosis genes that contribute to biofilm production, including pks1. In addition, we find that the ability to make pellicle biofilms is common among M. tuberculosis isolates from throughout the world, suggesting that this trait is relevant to TB propagation or persistence.
生物膜引起的感染非常普遍且具有高度持久性，表现出对抗生素高浓度的表型耐药性，并调节宿主免疫系统。由结核分枝杆菌引起的结核病（TB）与生物膜感染具有这些共同特性。为了鉴定结核分枝杆菌生物膜形成的遗传决定因素，我们使用体外菌膜生物膜测定法进行了小规模转座子筛选。我们鉴定了五个结核分枝杆菌突变体，它们在生物膜产生方面相对于亲本菌株 H37Rv 表现出可重复的衰减。最衰减的突变体之一是在 pks1 中中断，pks1 是一种聚酮合酶基因。当与 pks15 融合时，如一些结核分枝杆菌分离株中那样，pks1 有助于合成免疫调节性酚甘油酯（PGL）。然而，在 H37Rv 等具有分裂的 pks15 和 pks1 基因座的菌株中，不产生 PGL，并且 pks1 以前没有定义的作用。我们表明，pks1 互补独立于 pks1 在 PGL 合成中的已知作用恢复生物膜产生。我们还评估了生物膜形成、pks15/1 基因型和结核分枝杆菌系统地理学之间的关系。对结核分枝杆菌临床分离株的全球调查显示，pks15/1 基因座存在惊人的序列变异性，生物膜表型也存在很大差异。我们的研究确定了一些新的结核分枝杆菌基因，它们有助于生物膜的产生，包括 pks1。此外，我们发现，从世界各地分离的结核分枝杆菌分离株形成菌膜生物膜的能力很常见，这表明该特性与结核病的传播或持续存在有关。
