Fig 1.
Colony morphology of MSMB isolates on Ashdown’s Agar (ASA) compared to B. pseudomallei MSHR305.
ASA is considered a selective growth medium for Burkholderia pseudomallei. In this study, at least 20 different species demonstrated the ability to grow on ASA including multiple Burkholderia speices as well as Ralstonia, Cupriavidus, and Panoraea. Many different colony morphologies were observed during this study as evident in the pictures (a) proposed B. humptydooensisMSMB43, (b) unknown Burkholderia spp. MSMB 175, (c) B. multivorans MSMB105, (d) B. thailandensis MSMB60, (e) B. ubonensis MSMB153, (f) B. pseudomallei MSHR 305. Each strain was grown on ASA for 72 hours at 37°C aerobically.
Table 1.
Comparison of environmental species identified in the Darwin region of Australia.
Fig 2.
Phylogenetic analysis of environmental Burkholderia spp. sampled from soil in the Northern Territory of Australia.
A 335-bp region of the recA gene was sequenced and analyzed using Bayesian methods. The phylogenetic tree is the consensus of 19,000 trees and 11 million generations using the nucleotide substitution model GTR+G. Species and isolate names are shown for reference sequences. Clade A highlights the Pseudomallei group of Burkholderia species where we identified several isolates of proposed B. humptydooensis and B. thailandensis. Clade B highlights the large number of B. ubonensis isolates identified in the northern territory of Australia during this study. Clade C is the B. cepacia complex outside of B. ubonensis. Posterior probabilities are assigned at branch nodes (1 = 100%). Scale bar signifies nucleotide substitutions per site. Clade C demonstrates the diversity found within the B. cepacia complex. Several novel nodes, marked with an asterisk, are evident in this phylogenetic tree which may represent novel species.
Fig 3.
Geographical distribution of isolates from this study.
Circle size represents the number of isolates found at a specific sampling site and the color represents different species as determined by recA or 16s rRNA sequencing. Division of circles indicates that multiple species were found at a site. B. ubonensis is commonly found throughout Darwin and the surrounding areas. Several species were found in the same soil sample as B. pseudomallei including B. ubonensis, several B. cepacia complex species, proposed B. humptydooensis, Pandoraea, and Cupriavidus.