Genetic Diversities In Pcbs Polluted Soils And The Effect Of Biphenyl On Soil Microorganism

Taizhou, Zhejiang province is one of electric waste recycling sites in China. Many PCB-containing transformers and capacitors have been stored in Xiaoshan, Zhejiang province. Improper dismantling of the transformers and capacitors and leakages of PCBs in the storage seriously polluted the sites. In this research, Surface soils from Xiaoshan, Taizhou and Huajiachi (an agricultural experiment station, unpolluted site) were incubated with biphenyl at28℃for25days. The diversity of microbial functional genes was detected by Geochip. Combing the use of traditional microbial ecological research methods, PCR-DGGE and real-time PCR to explore the effect of PCBs on soil microorganism community structure and indicate the changes of soil bacterial community structure and the abundance of bphA gene in different soils induced with biphenyl. The main conclusions are as follows:(1) The total PCBs concentration in Xiaoshan and Taizhou soil was19.14-91.47mg/kg and0.27-5.02mg/kg, respectively. The signal intensities of majority genes in XS-1soil were significant higher than LQ-1and XS-2soils.(2) Bacterial numbers in native soils were as follows:Taizhou> Huajiachi> Xiaoshan. Compared with control treatment, bacterial abundance increased in biphenyl-amended Taizhou soil and decreased in biphenyl-amended Xiaoshan soil.(3) DGGE indicated that Proteobacteria was the dominant species. Three new DGGE bands corresponding to genus Sphingomonas, Polaromonas and unclassified y-Protrobacteria and four new DGGE bands corresponding to genus Sphingomonas, Pseudomonas and Acidobacteria were found in biphenyl-amended Xiaoshan and Taizhou soil, respectively. Some of them were highly silmar with the sequence of microbes that are related with organic compound degradation.(4) The bphA gene was detected in all samples and the bacterial species carrying the bphA gene in the studied soils are remarkably similar. Bacterium belongs to geneus Rhodococcus occurred in biphenyl-amended Taizhou soil and belongs to Pseudomonas disappeared in biphenyl-amended Xiaoshan soil. (5) bphD.l.B, bphD.1.C, bphD.2.A and bphD.2.B genes were measured by real-time PCR. No significant difference of the bphD.2.A or bphD.2.A/B genes was observed among Xiaoshan soils. The abundance of the bphD.1.C gene was the lowest compared with the other three genes in both Taizhou and Xiaoshan soils. Interestingly, the copy number of the bphD.2.A/B gene in biphenyl-amended Taizhou soil was about several orders of magnitude greater than that in the rest soils. Cloning analysis confirmed that the bacterium was consistent with the result obtained by PCR-DGGE analysis of the bphA gene.