Abstract
To isolate bacteria responsible for the biodegradation of naphthalene, BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylene), and aliphatic hydrocarbons in petroleum-contaminated soil, three enrichment cultures were established using soil extract as the medium supplemented with naphthalene, BTEX, or n-hexadecane. Community analyses showed that Paraburkholderia species were predominant in naphthalene and BTEX, but relatively minor in n-hexadecane. Paraburkholderia aromaticivorans BN5 was able to degrade naphthalene and all BTEX compounds, but not n-hexadecane. The genome of strain BN5 harbors genes encoding 29 monooxygenases including two alkane 1-monooxygenases and 54 dioxygenases, indicating that strain BN5 has versatile metabolic capabilities, for diverse organic compounds: the ability of strain BN5 to degrade short chain aliphatic hydrocarbons was verified experimentally. The biodegradation pathways of naphthalene and BTEX compounds were bioinformatically predicted and verified experimentally through the analysis of their metabolic intermediates. Some genomic features including the encoding of the biodegradation genes on a plasmid and the low sequence homologies of biodegradation-related genes suggest that biodegradation potentials of strain BN5 may have been acquired via horizontal gene transfers and/or gene duplication, resulting in enhanced ecological fitness by enabling strain BN5 to degrade all compounds including naphthalene, BTEX, and short aliphatic hydrocarbons in contaminated soil.