Genetic and Morphological Diversity of the Vietnamese Population of Burkholderia thailandensis

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.