Differences in Genomic Macrorestriction Patterns of Arabinose‐Positive (Burkholderia thailandensis) and Arabinose‐Negative Burkholderia pseudomallei

Abstract

We reported previously two biochemically and antigenically distinct biotypes of Burkholderia pseudomallei. These two distinct biotypes could be distinguished by their ability to assimilate L-arabinose . Some B. pseudomallei isolated from soil samples could utilize this substrate (Ara+), whereas the other soil isolates and all clinical isolates could not (Ara ). Only the Ara-isolates were virulent in animals and reacted with monoclonal antibody directed at the surface envelope, most likely the exopolysaccharide component. In the present study, pulsed-field gel electrophoresis was employed for karyotyping of these previously identified B. pseudomallei strains. We demonstrate here that the DNA macrorestriction pattern allows the differentiation between B. pseudomallei, which can assimilate L-arabinose, and the proposed B. thailandensis, which cannot do so. Bacterial strains from 80 melioidosis patients and 33 soil samples were examined by genomic DNA digestion with Ncol. Two major reproducible restriction patterns were observed. All clinical (Ara ) isolates and 9 Ara soil isolates exhibited macrorestriction pattern I (MPI), while 24 soil isolates (Ara+) from central and northeastern Thailand displayed macrorestriction pattern II (MPII). The study here demonstrated pulsed-field gel electrophoresis to be a useful tool in epidemiological investigation possibly distinguishing virulent B. pseudomallei from avirulent B. thailandensis or even identifying closely related species of Burkholderia .

Detection of Bacterial Virulence Genes by Subtractive Hybridization: Identification of Capsular Polysaccharide of Burkholderia pseudomallei as a Major Virulence Determinant

“…However, these two organisms differ in a number of ways and have been classified into two different species (7). The rRNA sequence of B. thailandensis differs from that of B. pseudomallei by 15 nucleotides, and there are significant differences in genomic macrorestriction patterns be-tween these organisms (10). The biochemical profiles of these two species differ in that B. thailandensis can utilize L-arabinose whereas B. pseudomallei does not (7,62).…”

Functional reconstitution, gene isolation and topology modelling of porins from Burkholderia pseudomallei and Burkholderia thailandensis

“…Although the two organisms are very similar ( [4,5], but see [5a]), they are different in their genetic and biochemical properties. The rRNA sequence of B. thailandensis differs from that of B. pseudomallei by 15 nucleotides, and there are significant differences in genomic macrorestriction patterns between the organisms [6]. The biochemical profiles of these two species differ in that B. thailandensis utilizes L-arabinose, whereas B. pseudomallei does not [7].…”

Distribution of type III secretion gene clusters in Burkholderia pseudomallei, B. thailandensis and B. mallei

“…It is possible to discriminate between the two biotypes by molecular approaches such as fliC variation [7,8] or multiplex PCR assays [9]. Furthermore, differences in genomic macrorestriction patterns between the two biotypes have been reported [10]. As the mechanisms of B. pseudomallei virulence are poorly understood, there is considerable interest in the identification of the specific factors determining the greater virulence of B. pseudomallei.…”