| Polychlorinated biphenyls(PCBs), including209congeners and isomers, are a class of typical, complex, and ubiquitous Persistent Organic Pollutants(POPs) in the environment. In recent30years, lots of studies have been concentrated on degradation of PCBs because of their environmental persistence, bioaccumulation, semi-volatile and biological toxicity. Biodegradation of PCBs has captured great attention in the field of environmental science and technology. One of the promising solutions is to obtain microbial strains capable of removing more PCB congeners aerobically at a high biotransformation rate.-Cultivation of microorganisms was stimulated by incubating polychlorinated biphenyl-polluted soils in Wenling and Xiaoshan with biphenyl as sole carbon and energy source. We chose Bacillus sp.T29and Corynebacterium sp.W5-for further study. The main results were as follows:(1) Both of Bacillus sp.T29and Corynebacterium sp.W5are Gram-positive bacteria with wide spectrum of carbon utilization. Bacillus sp.T29grows faster than Corynebacterium sp. W5, however Corynebacterium sp.W5can grow on more carbon source.(2) The enrichment of Xiaoshan, Bacillus sp.T29and Corynebacterium sp.W5can degrade PCBs with less than five chlorinated. Both biphenyl and benzoic acid can promote the degradation of PCBs, and the effect of benzoic acid is better than biphenyl.(3) Although biphenyl acted as carbon source to support the growth of Bacillus sp.T29and Corynebacterium sp.W5, its toxicity inhibited the growth of these two bacteria. The toxicity of benzoic acid is much less than biphenyl.(4) Both Cr and Cu inhibited the growth of Bacillus sp.T29and its utilization of benzoic acid. The above results show that Bacillus sp.T29and Corynebacterium sp.W5are efficient aerobic polychlorinated biphenyl-degrading bacteria which deserve further study. Benzoic acid is a better co-metabolism substrate than biphenyl. Heavy metals are likely to reduce the ability of bacteria to degrade PCBs. |
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