| As a typical environmental hormone pollutant, phthalic acid ester also has the property of persistent organic pollutants?pops?. With widely used in industry and agriculture, it was detected in the soil, ocean, air, drinking water, animals and plants currently. PAEs cause increasingly serious pollution to the ecological environment. At present, the toxic studies of PAEs have been focused on humans and animals, but the potential toxicity on microorganism has been neglected, especially few toxicological data of microbial community structures are available until now.A laboratory experiment was performed to evaluate the toxicological effects of DEHP on soil microbes function, structure and the influence of genetic diversity by means of the dilute plate method, Biolog, T-RFLP, PCR-DGGE and clone library technology at different concentrations?0, 0.1, 1, 10 mg and 50 mg DEHP per kg soil? on day 0 and the 7th, 14 th, 21 st, and 28 th day after treated by DEHP. A preliminary analysis of its mechanism has been made to provide a theoretical basis for the evaluation of its eco-toxicological effects of PAEs.The main results are as follows:?1? The number of bacteria, fungi and actinomycetes in soil was affected by phthalates DEHP. DEHP inhibited the number of bacteria, fungi and actinomycetes in the early time, which showed a good effect relationship that the concentration of DEHP was higher, the inhibition level was better. The number of microorganisms still was restrained exposured to high concentrations of DEHP in the mid-term, the number of microorganisms returned to normal levels from fluctuations gradually over time.?2? Soil microbial functional diversities of metabolic activities declined to a certain extent under the influence of DEHP. AWCD, Shannon indices, Simpson indices and Mc Intosh indices were inhibited by DEHP in different degrees in the early exposure, which indicated a downward trend of soil microbial activities, abundance, species dominance and uniformity. Inhibitory effecs on soil microbial activities and functional diversities were gradually weakened by DEHP and returned to normal levels. Under DEHP stress, the soil microbial metabolic efficiency of four types of carbon sources were significant affected and different concentrations of DEHP had different effects on different carbon sources utilization at different sampling times, and the metabolic efficiency of carbon source was relatively stable latterly.?3? The PCR-DGGE and T-RFLP were used to analyse the effects of DEHP on soil microbial genetic diversities. It was found that Proteobacteria accounted for a high percentage of all soil microflora polluted by DEHP, and its advantages were obvious. Abundance of soil microbial flora changed significantly through the analysis of T-RFs peak area and diversities indices in different time, and it increased and then decreased over time. Shannon indices were activated at the early stage, while Simpson indices and Mc Intosh indices were suppressed, and the species abundance, dominance and homogeneous degree of soil microbes were basically stable latterly.?4? Species of soil microbes decreased slightly than the control through constructing genomic library of the 14 th day's soil samples treated by DEHP. Proteobacteria was the most significant member of bacterial community in soil at higher concentrations(10?50mg·kg-1) of DEHP. Acidobacteria occupied an important position in all treatment groups and occupied the highest proportion in lower concentration(0.1?1mg·kg-1) group. Acidobacteria was found that it had a stronger adaptability in the concentration range designed by the experiment. |
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