| Because this kind of diesel oil has relatively high biological toxity and the residue is relatively permanent, people show more and more attention on how to remediate the polluted environment. Bioremediation of pesticides-contaminated environment, which exploits the ability of organisms to degrade and/or detoxify organic contamination, has been established as an efficient, economic, versatile, and environmentally sound treatment. Decontamination of polluted sites in our country with bioremediation has received increasing interest recently.Using diesel oil as unique carbon source, take soil sample from sewage control factory and gas station, compare change of diesel oil content in medium, microbe having the capacity of desulphurization was selected and named as Q10, Q14 and Q18 with efficiency of 36.0%, 39.3% and 42.1%, respectively. After managed with ultraviolet radiation, the highest desulphurization efficiency QY1 and QY4 was gained with efficiency of 47.5% and 52.2%. After isolation, purification this microbe as well as detection of its appearance, physiological and biochemical characteristics, growth characteristics, it was identified Pseudomonas sp., Flavobacterium sp. and Rhodococcus sp. according to bacteriological analytical manual (FDA) and taxology of microorganism. The reduction in surface tension was observed in the experiments, strain Q18 may be a potential biosurfactant producer.In order to construct highly effective microbial consortium, 9 bacteria were selected by initial oil test. Their functions in the process of degrading petroleum were detected by GC-MS analysis and by which we construct some rational consortiums. The consortium 2, consisted of strain Q10, Q14, Q18 and QY4, was more efficient in diesel oil degradation than the individual isolates with efficiency of 62.1%. But the consortium consisted by random was less efficient in diesel oil degradation. The soil culture conditions for the biodegradation of diesel by mixed bacteria were also investigated. The optimal culture conditions were: cultivated temperature 30℃, initial pH value 7.0 and the percentage of diesel concentration 1%.By the means of research the influence of surfactants on the growth of mixed bacteria and test the effects of surfactants to the biodegradation of diesel, we can make some conclusions that: the influence of surfactants on the growth of bacteria may correlate to the concentration of surfactants. With the increased of the concentration of surfactants, the delay of logarithmic growth phase extended. In our experiment, the inhibition to the growth of mixed bacteria was anion surfactant SDS>nonionic surfactant Tween-80>nonionic surfactant TX-100. In the presence of the anion surfactants, the degradation of diesel was not increased. But adding the nonionic surfactants can increase the degradation of diesel. If the concentration of Tween-80 and TX-100 under 100mg L-1, with the concentration of the nonionic surfactants increased, the degradation efficiency of diesel enhanced.And the plants, alfalfa and Indian mustard, do improve the effectiveness of diesel oil biodegradation. Both of them along with bacteria exhibited more effective degradation of diesel oil than isolates alone. The diesel oil biodegradation due to combination of the plants and the bacteria go up to 69.2%. Indian mustard shows more effective in the improvement of the biodegradation of diesel oil than alfalfa. The strain Q18 had the greatest degradation ability for diesel oil in sandy loam. Both alfalfa and mustard along with bacteria was more effective in degradation of diesel oil than bacteria alone. Mustard resulted in the maximum diesel oil reduction in sandy loam and clay, but alfalfa resulted in the maximum diesel oil reduction in sandy.
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