Abstract

Burkholderia thailandensis and B. pseudomallei are closely related gram-negative saprophytic microbes. Recently, variant strains of B. thailandensis bearing a capsular polysaccharide gene cluster (Bp-like CPS), which exhibits a high similarity to the corresponding cluster in B. pseudomallei, have been discovered. In the present study, we aimed to determine the presence of B. thailandensis capsular variant strains (BTCVs) in the environment of Vietnam. Multilocus species-specific PCR and MLST were used to identify the strains. Eighty-seven B. thailandensis soil isolates from Southern and Central Vietnam were investigated. Six pairs of primers were designed to detect the genes of Bp-like CPS clusters. 11 BTCV strains were revealed. The strains bearing Bp-like CPS clusters formed mainly pseudomallei-like rough and wrinkled colonies. It was also shown that L1629S and T1942A polymorphisms in type I polyketide synthase WcbR are closely associated with pseudomallei-like colony morphology in EPS-expressing strains of the main population of B. thailandensis in Vietnam. The findings indicate a high degree of genetic heterogeneity accompanied by phenotypic diversity of B. thailandensis in Vietnam.

中文翻译：

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越南伯克霍尔德氏菌种群的遗传和形态多样性

摘要

Burkholderia thailandensis和B. pseudomallei是密切相关的革兰氏阴性腐生微生物。最近，发现了带有荚膜多糖基因簇（Bp-like CPS）的B. thailandensis变异菌株，该基因簇与B. pseudomallei中的相应簇具有高度相似性。在本研究中，我们旨在确定越南环境中是否存在B. thailandensis荚膜变异菌株 (BTCV)。多位点物种特异性 PCR 和 MLST 用于鉴定菌株。八十七B. thailandensis研究了越南南部和中部的土壤分离株。设计了六对引物来检测Bp样CPS簇的基因。揭示了 11 个 BTCV 毒株。携带Bp样CPS簇的菌株主要形成假槌状粗皱菌落。研究还表明，I 型聚酮化合物合成酶 WcbR 中的 L1629S 和 T1942A 多态性与越南B. thailandensis主要种群的 EPS 表达菌株中的假槌状菌落形态密切相关。研究结果表明，越南的B. thailandensis具有高度的遗传异质性以及表型多样性。