title: Effects of enrichment with phthalate on polycyclic aromatic hydrocarbon biodegradation in contaminated soil.
abstract: The effect of enrichment with phthalate on the biodegradation of polycyclic aromatic hydrocarbons (PAH) was tested with bioreactor-treated and untreated contaminated soil from a former manufactured gas plant (MGP) site. Soil samples that had been treated in a bioreactor and enriched with phthalate mineralized (14)C-labeled phenanthrene and pyrene to a greater extent than unenriched samples over a 22.5-h incubation, but did not stimulate benzo[a]pyrene mineralization. In contrast to the positive effects on (14)C-labeled phenanthrene and pyrene, no significant differences were found in the extent of biodegradation of native PAH when untreated contaminated soil was incubated with and without phthalate amendment. Denaturing-gradient gel electrophoresis (DGGE) profiles of bacterial 16S rRNA genes from unenriched and phthalate-enriched soil samples were substantially different, and clonal sequences matched to prominent DGGE bands revealed that beta-Proteobacteria related to Ralstonia were most highly enriched by phthalate addition. Quantitative real-time PCR analyses confirmed that, of previously determined PAH-degraders in the bioreactor, only Ralstonia-type organisms increased in response to enrichment, accounting for 89% of the additional bacterial 16S rRNA genes resulting from phthalate enrichment. These findings indicate that phthalate amendment of this particular PAH-contaminated soil did not significantly enrich for organisms associated with high molecular weight PAH degradation or have any significant effect on overall degradation of native PAH in the soil.
authors.affiliation: Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, NC 27599, USA. drsingle@email.unc.edu
authors.forename: David R
authors.initials: DR
authors.lastname: Singleton
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Richardson
authors.forename: Michael D
authors.initials: MD
authors.lastname: Aitken
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D052918:Environmental Restoration and Remediation / Q000379:methods; D010795:Phthalic Acids / Q000378:metabolism*; D011083:Polycyclic Compounds / Q000378:metabolism*; D043367:Ralstonia / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D010795:Phthalic Acids; D011083:Polycyclic Compounds; D012989:Soil Pollutants