| Polycyclic Aromatic Hydrocarbons(PAHs),one of the most important organic pollutants,are widely found in petroleum polluted environments,and can cause carcinogenesis,teratogenesis and mutation.Through the study found that some bacteria in nature can rapidly degrade PAHs,such as Sphingomonas paucimobilis,Acinetobacter,etc.,but they are in the natural environment in efficiency is limited,due to the carbon source,nitrogen source,the type of PAHs and the bioavailability of bacteria,and the interaction between bacteria and other related conditions limit,causes the degradation efficiency is low.Compared with single bacteria degradation,flora can improve the degradation efficiency of PAHs by utilizing the internal relationship and synergy between single bacteria.This study in Jilin baicheng momo region soil contaminated by oil as the research sample,first the method of enrichment culture,with PAHs as the sole carbon source,screening get PAHs High efficient degradation bacteria,study the ability to degrade pyrene,by single factor experiments to explore the flora in different temperature,flora liquid initial concentration,pyrene end conditions on the degradation efficiency,the effect of using High performance liquid(High performance liquid,HPLC)determination of the residual content of pyrene in sample,calculate the flora of pyrene degradation rate;Secondly,isolated from flora in three single bacteria can efficiently degrade pyrene,through the morphological identification and 16 S rRNA gene sequence analysis to determine the single bacteria species,the absorbance of flora solution was measured by ultraviolet spectrophotometer at 600 nm,the growth stage of bacteria was observed,and the growth curve was drawn.The effects of three single bacteria on degradation efficiency under different temperature,initial concentration of bacteria solution and final concentration of Pyr were studied by single factor experiment.The residual content of pyrene in the sample was determined by HPLC,and the degradation rate of pyrene was calculated;Finally,according to the optimal degradation conditions,the single bacteria were mixed in different proportions to construct an artificial compound bacteria,and the degradation efficiency of the bacteria on pyrene was measured to obtain the proportion of strains with more efficient degradation,which provides a certain experimental basis for the practical application of remediation of soil oil pollution.The results showed that the degradation rate of the isolated flora reached 99.97%when the temperature was 30?,the initial concentration of flora solution was 0.1,and the final concentration of pyrene was 50mg/L,indicating that these conditions were the best conditions for the degradation of flora.Three strains of single bacteria were isolated from the microflora,named pyr-1,pyr-2 and pyr-3.By morphological identification and 16 S rRNA gene sequence analysis,strain pyr-1 was Pseudomonas,strain pyr-2 was Rhizobiums,and strain pyr-3 was Bacillus.The degradation conditions of the three strains were optimized,and the optimal degradation conditions for each strain were obtained.The results showed that the maximum degradation rate of strain pyr-1 was 67.14% when the temperature was 35?,the initial concentration of strain solution was 0.2,and the final concentration of pyrene was 100 mg/L.When the temperature was 30?,the initial concentration of strain pyr-2 was 0.1,and the final concentration of pyrene was 50 mg/L,the degradation rate of strain pyr-2 was54.23%.The degradation rate of strain pyr-3 reached the highest 58.04% when the temperature was 30?,the initial concentration was 0.2,and the final concentration of pyrene was 50 mg/L.By conditional analysis,when strains pyr-2 and pyr-3 were mixed at a ratio of 1:1.5,the degradation efficiency was 70.21% when the temperature was 30? and the final concentration of pyrene was 50 mg/L,indicating that 1:1.5was the best ratio. |
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