Research Of Microorganisms On The Repairing Of Petroleum-contaminated Soil By Straw Strengthening

Five(H1?H2?H3?H4?H5)kinds of petroleum degrading bacteria were screened out from oil contaminated soil.Two strains with high degradation efficiency were selected as the experimental objects.Design and synthesis of specific primers,the functional genes related to alkanes,aromatic hydrocarbons and polycyclic aromatic hydrocarbons in DNA were detected by DNA extraction-PCR amplification technology;The high efficient mixed bacteria group was constructed by using two kinds of experimental strains,the degradation rate of petroleum hydrocarbons in 5 days was the objective of the study,designing experiment scheme by single factor experiment and response surface method,to explore the effect of salt concentration initial oil content and inoculation amount on the growth of bacteria,and determine the best parameter combination of the highest degradation rate and culture of bacteria in the best condition;The immobilized microorganism was prepared by using MG as carrier,applying to in-situ remediation of simulated petroleum contaminated soil in pot experiment,to study the decomposition characteristics of straw carrier in soil and the effect of immobilized microorganism on the remediation of oil contaminated soil by periodically measuring the content of humus,humic acid and petroleum hydrocarbons,based on the analysis of the correlation between microbial quantity,humus content and hydrocarbon degradation rate,the effect of straw carrier on microbial remediation of oil contaminated soil was investigated.By regularly measuring soil enzyme activity,bacteria,fungi,actinomycetes number and microbial community structure,the straw immobilized microbial effects on the soil microflora and exogenous bacteria and indigenous bacteria interactions were studied.The 5 days degradation rate of H4 and H3 were the highest among the strains H1,H2,H3,H4,H5,they were 31.48% and 37.56%,respectively.Selecting H3 and H4 as the experimental object.DNA extraction-PCR amplification results showed that,two strains both contain functional genes related to the degradation of alkanes,aromatic hydrocarbons and polycyclic aromatic hydrocarbons in petroleum pollutants including alkane hydroxylase gene,alkanes and oxygen enzyme gene,catechol 2,3 double plus oxygen enzyme gene,?-subunit naphthalene double plus oxygen enzyme iron sulfur protein gene,biphenyl double plus oxygen enzyme gene,glutathione s-transferase genes.Selecting bacteria activation volume ratio of 3:2 of strains H3 and H4 to construct efficient mixed bacteria,the 5 days hydrocarbon degradation rate was 47.50%.The best conditions for the bacterial population growth by single factor experiment and response surface method were initial oil content 10.13g/L,inoculation amount 15.08%,salt concentration 5.19g/L,5 days oil degradation rate was 41.56%.The straw carrier decomposed in soil remediation process,the humus content in soil was increased from 11.17g/kg to 22.97g/kg,and humic acid content was increased by 78.54% in the soil with straw immobilized microorganism;In the soil with straw carrier,the humus content increased from 11.07g/kg to 17.57g/kg,the content of humic acid increased by 49.45%,and the increase were higher than that of the soil without straw carrier;The cumulative degradation rate of petroleum hydrocarbons and microorganisms number in the soil with immobilized microorganism were higher than those in other experimental groups.Compared with the humus content,the correlation between microbial quantity and petroleum hydrocarbon degradation rate was more significant,the exogenous bacteria played a major role in the repair process and straw carrier played a significant role in promoting.The activities of dehydrogenase and polyphenol oxidase,the number of bacteria,fungi,actinomycetes and soil microbial community were increased in all kinds of repair methods,exogenous bacteria and indigenous bacteria showed a trend from competition to synergy during the repair process.The biological characteristics of oil contaminated soil were improved by the addition of straw carrier,and the process of microbial remediation of petroleum contaminated soil was enhanced.