Journal article
The effects of individual PCB congeners on the soil bacterial community structure and the abundance of biphenyl dioxygenase genes
Environment international, Vol.36(8), pp.901-906
2010
DOI: 10.1016/j.envint.2009.07.015
PMCID: PMC2928393
PMID: 19716603
Abstract
Polychlorinated biphenyls (PCBs) are toxic environmental contaminants that represent a class of 209 congeners characterized by different degrees of chlorination and substitution patterns. Most of experimental studies about microbial degradation of PCBs have been conducted on PCB mixtures, even though evidence accumulated in bacteria and other organisms shows that exposure to different congeners may have different biological effects. Microcosm experiments were conducted using aerobic agitated soil slurries individually exposed to PCB congeners with different degrees of chlorination: PCB-3, 15, 28, and 77, and the commercial mixture Aroclor 1242. After four weeks of incubation, PCBs were analyzed by gas chromatography/mass spectrometry (GC/MS) showing different transformation extents: With the exception of PCB-15 that was not significantly transformed (7%), biodegradation rates decreased with the degree of chlorination, from 75% for PCB-3 to 22% for PCB-77 and Aroclor 1242. The bacterial abundance, as measured by colony counting and 16S rDNA quantification by real-time PCR, was lower (of about 40%) in soil microcosms exposed to the higher-chlorinated congeners, PCB-28, PCB-77, and Aroclor 1242, as compared to non-exposed soils and soils exposed to the lower-chlorinated congeners, PCB-3 and PCB-15. The relative abundance of different taxonomic groups, as determined by real-time PCR, revealed an increase of β-Proteobacteria and Actinobacteria in all microcosms exposed to PCBs, as compared with non-exposed soil. In addition, exposure to PCB-77 and Aroclor 1242 resulted in a higher abundance of α-Proteobacteria and Acidobacteria. Globally, these results suggest that exposure to PCBs (and especially to higher-chlorinated congeners and Aroclor 1242) selected bacterial groups involving most known PCB degraders, i.e., β-Proteobacteria and Acidobacteria. The quantification of biphenyl dioxygenase (BPH) genes — involved in the aerobic degradation of PCBs — using real-time PCR showed that exposure to all PCB congeners and Aroclor 1242 resulted in a marked increase of two out of the four BPH genes tested, similarly suggesting the selection of PCB-degrading bacteria. This paper showed that exposure to different PCB congeners leads to different structures of the soil bacterial community and BPH genes expression patterns.
Details
- Title: Subtitle
- The effects of individual PCB congeners on the soil bacterial community structure and the abundance of biphenyl dioxygenase genes
- Creators
- Paola A Correa - West Virginia University, Morgantown, WV, United StatesLianShin Lin - West Virginia University, Morgantown, WV, United StatesCraig L Just - University of Iowa, Iowa City, IA, United StatesDingfei Hu - University of Iowa, Iowa City, IA, United StatesKeri C Hornbuckle - University of Iowa, Iowa City, IA, United StatesJerald L Schnoor - University of Iowa, Iowa City, IA, United StatesBenoit Van Aken - Temple University, Philadelphia, PA, United States
- Resource Type
- Journal article
- Publication Details
- Environment international, Vol.36(8), pp.901-906
- DOI
- 10.1016/j.envint.2009.07.015
- PMID
- 19716603
- PMCID
- PMC2928393
- NLM abbreviation
- Environ Int
- ISSN
- 0160-4120
- eISSN
- 1873-6750
- Publisher
- Elsevier Ltd
- Language
- English
- Date published
- 2010
- Academic Unit
- Civil and Environmental Engineering; Occupational and Environmental Health; Iowa Superfund Research Program
- Record Identifier
- 9983997970202771
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