Abundance of Dioxygenase Genes Similar to Ralstonia sp. Strain U2 nagAc Is Correlated with Naphthalene Concentrations in Coal Tar-Contaminated Freshwater Sediments

• Autores: Dionisi, Hebe Monica; Chewning, Christopher S.; Morgan, Katherine H.; Menn, Fu Min; Easter, James P.; Sayler, Gary S.
• Año de publicación: 2004
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: DIOXYGENASE GENES; RALSTONIA SP.; REAL-TIME PCR
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We designed a real-time PCR assay able to recognize dioxygenase large-subunit gene sequences with more than 90% similarity to the Ralstonia sp. strain U2 nagAc gene (nagAc-like gene sequences) in order to study the importance of organisms carrying these genes in the biodegradation of naphthalene. Sequencing of PCR products indicated that this real-time PCR assay was specific and able to detect a variety of nagAc-like gene sequences. One to 100 ng of contaminated-sediment total DNA in 25-ml reaction mixtures produced an amplification efficiency of 0.97 without evident PCR inhibition. The assay was applied to surficial freshwater sediment samples obtained in or in close proximity to a coal tar-contaminated Superfund site. Naphthalene concentrations in the analyzed samples varied between 0.18 and 106 mg/kg of dry weight sediment. The assay for nagAc-like sequences indicated the presence of (4.1 ± 0.7) x 103 to (2.9 ± 0.3) x 105 copies of nagAc-like dioxygenase genes per mg of DNA extracted from sediment samples. These values corresponded to (1.2 ± 0.6) x 105 to (5.4 ± 0.4) x 107 copies of this target per g of dry weight sediment when losses of DNA during extraction were taken into account. There was a positive correlation between naphthalene concentrations and nagAc-like gene copies per microgram of DNA (r = 0.89) and per gram of dry weight sediment (r = 0.77). These results provide evidence of the ecological significance of organisms carrying nagAc-like genes in the biodegradation of naphthalene.
Fil: Dionisi, Hebe Monica. University of Tennessee; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina
Fil: Chewning, Christopher S.. University of Tennessee; Estados Unidos
Fil: Morgan, Katherine H.. University of Tennessee; Estados Unidos
Fil: Menn, Fu Min. University of Tennessee; Estados Unidos
Fil: Easter, James P.. University of Tennessee; Estados Unidos
Fil: Sayler, Gary S.. University of Tennessee; Estados Unidos