Combined Effects Of Acetochlor And Copper On Indigenous Microoranism Communities In Phaeozem

Joint toxicological effects of acetochlor and copper on indigenous bacterial communities in phaeozem were investigated by using the traditional toxicity assessment methods combined with the modern molecular biotechnology. The polyphasic approach combines (i) microbial enumeration with media, (ii) substrate-induced respiration(SIR), (iii) dehydrogenase activity, and (iv) denaturing gradient gel electrophoresis (DGGE) fingerprinting of total community DNA with bacterial primers. We had established and developed a simple and rapid protocol for genome extraction and 16S rDNA amplification from phaeozem. Meantime, one bacteria capable of utilizing acetochlor as sole carbon and energy sources was isolated from polluted phaeozem.It was indicated that acetochlor and Cu2+ had a synergic inhibitory effect on the amount of culture-dependent viable microorganisms including bacteria (93.74%), actinomyces (93.0%), nitrogen-fixing bacteria (88.76%), silicate bacteria (96.47%) and phosphorus-mineralization bacteria (95.56%), as well as the activity of soil dehydrogenase (35.03%). The increase in SIR and the amount of fungi were significantly promoted by the two pollutants. Total DNA in soil was extracted using the optimized lysis buffer and 16S rDNA was amplified by nest-PCR and changing temperature condition. Similarity dendrograms showed that the bacterial community structures of the polluted soils and the clean soil without pesticide application were prominently different each other. Microbial community structures of phaeozem with long-term herbicides application were similar to those treated using higher concentration of acetochlor and Cu2+ simultaneously. The similaritycoefficient was up to 88%. There were three special bands in both.The degradation rate of acetochlor by strain SZ4 was 62%. It was elementarily considered to be belonged to Klebsiella pneumonias, based on the sequence analyses of 16S rDNA.