The effects of individual PCB congeners on the soil bacterial community structure and the abundance of biphenyl dioxygenase genes.
The effects of individual PCB congeners on the soil bacterial community structure and the abundance of biphenyl dioxygenase genes.
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DOI：
10.1016/j.envint.2009.07.015
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发表时间：
2010-11
影响因子：
11.8
通讯作者：
Van Aken, Benoit
中科院分区：
文献类型：
--
作者：
Correa, Paola A.;Lin, LianShin;Just, Craig L.;Hu, Dingfei;Hornbuckle, Keri C.;Schnoor, Jerald L.;Van Aken, Benoit
关键词：
多氯联苯是一类有毒的环境污染物，代表209种同系物，具有不同的氯化程度和取代模式。大多数关于微生物降解多氯联苯的实验研究都是在多氯联苯混合物上进行的，尽管在细菌和其他生物中积累的证据表明，暴露在不同的同系物中可能会产生不同的生物效应。微宇宙实验使用好氧搅拌土壤浆液，分别暴露于不同氯化程度的多氯联苯同系物：多氯联苯-3、15、28和77，以及商业混合物Aroclor 1242。培养4周后，用气相色谱/质谱仪(GC/MS)分析显示不同转化程度的多氯联苯：除没有显著转化的多氯联苯(7%)外，生物降解率随着氯化程度的增加而下降，从多氯联苯-3的75%下降到多氯联苯-77和Aroclor 1242的22%。通过菌落计数和实时荧光聚合酶链式反应(Real-Time PCR)16S rDNA定量测定，暴露于高氯化同系物PCB28、PCB77和Aroclor 1242的土壤微宇宙中的细菌丰度低于非暴露土壤和低氯化同系物PCB3和PCB15的土壤。实时定量聚合酶链式反应测定不同分类类群的相对丰度表明，与非暴露土壤相比，暴露于多氯联苯的所有微宇宙中的β-变形杆菌和放线杆菌数量都有所增加。此外，接触PCB77和Aroclor1242会导致α-变形杆菌和酸性细菌的丰度增加。从全球来看，这些结果表明，接触多氯联苯(特别是较高氯化的同系物和Aroclor1242)选择了涉及最已知的多氯联苯降解物的细菌群，即β-变形杆菌和酸性细菌。利用实时定量聚合酶链式反应对参与多氯联苯好氧降解的联苯双加氧酶(BPH)基因进行了定量，结果表明，暴露于所有多氯联苯同系物和Aroclor 1242中，所测试的四个BPH基因中有两个显著增加，同样表明选择了多氯联苯降解菌。研究表明，暴露于不同的多氯联苯同系物会导致土壤细菌群落结构和BPH基因表达模式的不同。
Polychlorinated biphenyls (PCBs) are toxic environmental contaminants that represent a class of 209 congeners characterized by different degree 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.
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影响因子：
2.8
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