Bacterial community in dioxin contaminated soil and mud samples from Danang airport
was enumerated and studied for their potential degradation capability against three-ring compound
carbazol. The cell number was determined on nutrient rich medium and on mineral medium
supplemented with carbazol. It has been showed that number of cells presented in mud samples
was significantly higher than in soil samples, in the range of 1 magnitude order. About 50% of the
total cell number in each sample grown on the medium with carbazol. Analyzing 12 representative
strains selectively isolated on the carbazol containing medium by using the ARDRA method with
two endonucleases HaeIII and MspI showed that bacterial community at the studied areas was
highly diversified. However non from these isolates could degrade carbazol significantly. Via
enrichment and isolation steps using carbazol as the only energy and carbon sources, two carbazol
degrading isolates R03 and R05 were obtained. Phylogenetic analyses based on 16S rDNA
sequences showed that these strains were most affiliated to Bacillus and Archromobacter species,
the most closely related species were Achromobacter xylosoxydans (99% homology) and Bacillus
subtilis (98% homology). These strains were therefore designated the names Bacillus sp. R03 and
Achromobacter sp. R05.
