Mycoplasmas are wall-less bacteria with many species spread across various animal hosts in which they can be pathogenic. Despite their reduced anabolic capacity, some mycoplasmas are known to secrete hetero- and homopolysaccharides, which play a role in host colonization through biofilm formation or immune evasion, for instance. This study explores how widespread the phenomenon of capsular homopolysaccharide secretion is within mycoplasmas, and investigates the diversity of both the molecules produced and the synthase-type glycosyltransferases responsible for their production. Fourteen strains representing 14 (sub)species from four types of hosts were tested in vitro for their polysaccharide secretion using both specific (immunodetection) and nonspecific (sugar dosage) assays. We evidenced a new, atypical homopolymer of β-(1 → 6)-glucofuranose (named glucofuranan) in the human pathogen Mycoplasma (M.) fermentans, as well as a β-(1 → 6)-glucopyranose polymer for the turkey pathogen M. iowae and galactan (β-(1 → 6)-galactofuranose) and β-(1 → 2)-glucopyranose for M. bovigenitalium infecting ruminants. Sequence and phylogenetic analyses revealed a huge diversity of synthases from varied Mycoplasma species. The clustering of these membrane-embedded glycosyltransferases into three main groups was only partially correlated to the structure of the produced homopolysaccharides.

中文翻译：

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支原体属细菌中的荚膜多糖生产：所谓的最小细菌的途径和合酶的巨大多样性


支原体是无壁细菌，许多物种分布在各种动物宿主中，它们可能具有致病性。尽管它们的合成代谢能力降低，但已知一些支原体会分泌异多糖和同多糖，例如，它们通过生物膜形成或免疫逃避在宿主定植中发挥作用。本研究探讨了荚膜同多糖分泌现象在支原体中的普遍性，并调查了产生的分子和负责其产生的合酶型糖基转移酶的多样性。使用特异性（免疫检测）和非特异性（糖剂量）测定法，在体外测试了来自 4 种宿主的 14 个（亚）物种的 14 种菌株的多糖分泌情况。我们证明了人类病原体支原体 （M.） 发酵物中 β-（1 → 6）-呋喃葡萄糖（称为呋喃葡萄糖）的新型非典型均聚物，以及用于火鸡病原体 M. iowae 的 β-（1 → 6）-吡喃葡萄糖聚合物和半乳聚糖 （β-（1 → 6）-半乳糖呋喃糖）和 β-（1 → 2）-吡喃葡萄糖用于感染牛生殖分枝杆菌的反刍动物。序列和系统发育分析揭示了来自不同支原体物种的合成酶的巨大多样性。这些膜包埋的糖基转移酶聚成三个主要组与产生的同多糖的结构仅部分相关。