ABSTRACT
A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, without enrichment, on minimal salts basal (MSB) agar containing 0.01% yeast extract, with BTEX as the sole carbon and energy source. Taxonomic analyses showed that the isolate belonged to Pseudoxanthomonas spadix, and until now, the genus Pseudoxanthomonas has not included any known BTEX degraders. The BTEX biodegradation rate was very low in MSB broth, but adding a small amount of yeast extract greatly enhanced the biodegradation. Interestingly, degradation occurred very quickly in slurry systems amended with sterile soil solids but not with aqueous soil extract. Moreover, if soil was combusted first to remove organic matter, the enhancement effect on BTEX biodegradation was lost, indicating that some components of insoluble organic compounds are nutritionally beneficial for BTEX degradation. Reverse transcriptase PCR-based analysis of field-fixed mRNA revealed expression of the tmoA gene, whose sequence was closely related to that carried by strain BD-a59. This study suggests that strain BD-a59 has the potential to assist in BTEX biodegradation at contaminated sites.
Subject(s)
Benzene Derivatives/metabolism , Benzene/metabolism , Biodegradation, Environmental , Soil Microbiology , Xanthomonadaceae/classification , Xanthomonadaceae/metabolism , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Gene Expression Profiling , Genes, rRNA , Korea , Molecular Sequence Data , Phylogeny , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Sequence Homology, Nucleic Acid , Xanthomonadaceae/isolation & purificationABSTRACT
A Gram-negative, strictly aerobic, non-spore-forming bacterium, designated strain BD-c194(T), was isolated from diesel-contaminated soil in Geoje, Korea. The cells were short, motile rods with single polar flagella. Growth of strain BD-c194(T) was observed between 15 and 45 degrees C (optimally at 30-35 degrees C) and between pH 6.0 and 9.5 (optimally at pH 7.5-9.0). The predominant fatty acids were 11-methyl C(18 : 1)omega7c, C(16 : 0), C(18 : 1)omega7c, C(18 : 0) and an unknown fatty acid (equivalent chain-length 18.814); a large amount of phosphatidylglycerol and a small amount of diphosphatidylglycerol were present as polar lipids. The G+C content of the genomic DNA was 60.8 mol% and the major isoprenoid quinone was Q-10. A comparative 16S rRNA gene sequence analysis showed that strain BD-c194(T) formed a well-defined phyletic lineage within the genus Devosia (with 100 % bootstrap support). The levels of 16S rRNA gene sequence similarity with respect to the type strains of other Devosia species ranged from 95.0 to 96.1 %. On the basis of chemotaxonomic data and molecular properties, strain BD-c194(T) represents a novel species within the genus Devosia, for which the name Devosia geojensis sp. nov. is proposed. The type strain is BD-c194(T) (=KCTC 22082(T) =DSM 19414(T)).
