Singapore Centre for Environmental Life Science Engineering, Nanyang Technological University, Singapore, Singapore.
School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
J Bacteriol. 2018 Nov 26;200(24). doi: 10.1128/JB.00361-18. Print 2018 Dec 15.
Like many bacteria, encodes a number of adhesins involved in colonization or infection of different niches. Two well-studied adhesins, aggregation substance (AS) and endocarditis- and biofilm-associated pili (Ebp), both contribute to biofilm formation on abiotic surfaces and in endocarditis, suggesting that they may be expressed at the same time. Because different regulatory pathways have been reported for AS and Ebp, here, we examined if they are coexpressed on the same cells and what is the functional impact of coexpression on individual cells and within a population. We found that while Ebp are only expressed on a subset of cells, when Ebp and AS are expressed on the same cells, pili interfere with AS-mediated clumping and impede AS-mediated conjugative plasmid transfer during planktonic growth. However, when the population density increases, horizontal gene transfer rates normalize and are no longer affected by pilus expression. Instead, at higher cell densities during biofilm formation, Ebp and AS differentially contribute to biofilm development and structure, synergizing to promote maximal biofilm formation. Most bacteria express multiple adhesins that contribute to surface attachment and colonization. However, the network and relationships between the various adhesins of a single bacterial species are less well understood. Here, we examined two well-characterized adhesins in , aggregation substance and endocarditis- and biofilm-associated pili, and found that they exhibit distinct functional contributions depending on the growth stage of the bacterial community. Pili interfere with aggregation substance-mediated clumping and plasmid transfer under planktonic conditions, whereas the two adhesins structurally complement one another during biofilm development. This study advances our understanding of how , a ubiquitous member of the human gut microbiome and an opportunistic pathogen, uses multiple surface structures to evolve and thrive.
像许多细菌一样， 编码了许多参与不同生态位定殖或感染的黏附素。两种研究得很好的 黏附素，聚集物质 (AS) 和心内膜炎和生物膜相关菌毛 (Ebp)，都有助于生物膜在非生物表面和心内膜炎中的形成，这表明它们可能同时表达。由于已经报道了不同的调节途径用于 AS 和 Ebp，在这里，我们检查了它们是否在同一细胞上共表达，以及共表达对单个细胞和群体的功能影响。我们发现，虽然 Ebp 仅在一部分细胞上表达，但当 Ebp 和 AS 在同一细胞上表达时，菌毛会干扰 AS 介导的聚集，并阻碍 AS 介导的接合质粒在浮游生长期间转移。然而，当种群密度增加时，水平基因转移率正常化，不再受菌毛表达的影响。相反，在生物膜形成过程中较高的细胞密度下，Ebp 和 AS 对生物膜的发展和结构有不同的贡献，协同促进最大的生物膜形成。大多数细菌表达多种黏附素，有助于表面附着和定植。然而，单个细菌物种的各种黏附素之间的网络和关系了解得较少。在这里，我们研究了 中的两种特征明显的黏附素，聚集物质和心内膜炎和生物膜相关菌毛，发现它们在细菌群落的生长阶段表现出不同的功能贡献。菌毛在浮游条件下干扰聚集物质介导的聚集和质粒转移，而在生物膜发育过程中，这两种黏附素在结构上相互补充。这项研究增进了我们对 如何利用多种表面结构来进化和生存的理解， 是人类肠道微生物组中的一种普遍存在的成员，也是一种机会性病原体。
