Isolation Of The Dominant Bacteria With Petroleum Degradation In The Permafrost Regions Of The Qinghai-tibetan Plateau And Its Application To Bioremediation Of Petroleum-contaminated Soil

The Qinghai-Tibet Plateau is a plateau permafrost zone with the fragile ecological environment.The China-Russian crude oil pipeline and the Golmud-Lhasa products pipeline,as the china's main oil pipelines,both cross permafrost regions and seasonally permafrost regions,whose freeze-thaw effect has caused multiple oil leaks.The problem of environmental pollution has become increasingly prominent.In this study,the bioremediation technology is the core,using the research method of the combination of field experiments and indoor simulations.The Beibeihe area of the Qinghai-Tibetan Plateau was selected as the experimental site artificially polluted by oil and diesel.The dominant bacteria group for degrading petroleum hydrocarbons identified by the Mi Seq high-throughput sequencing was to conduct low-temperature isolation,enrichment and domestication experiments.The study of effects of biodegradation of oil,improving on biodegradation of oil by adding auxiliaries as well as remediation efficiency of petroleum hydrocarbons contaminated soil provides technical support for the biodegradation of oil contaminated soil in the permafrost zone.The main research results of this experiment are as follows:(1)The Mi Seq high-throughput sequencing research showed the petroleum hydrocarbon pollution could change soil microbial diversity and community structure,but different petroleum hydrocarbon substances showed different response characteristics to petroleum pollution,indicating that SLO(oil-contaminated soil samples)diversity was highest,followed by uncontaminated soil samples(TS,MS),and the the lowest diversity of four soil samples was SDO(diesel-contaminated soil samples).The difference of community structure was big between SDO,SLO and uncontaminated soil samples,and so was the difference between SDO and SLO.There were 7 genera identified with the function of petroleum hydrocarbon pollutants degradation,including Sulfuritalea,Rhodococcus,Rhodoplanes,Sphingomonas,Alkanindiges,Nocardioides and Actinobacteria_norank.(2)The simulation of artificial oil pollution in the Beibeihe area of the Qingdai-Tibetan Plateau provides basic research materials for the screening of petroleum degradation microorganisms in the laboratory.Through the monitoring of physical and chemical properties and temperature of the soil in the site,the low-temperature simulation conditions in the laboratory were constructed.The microorganisms in the petroleum-contaminated soil were screened and re-screened to achieve the isolation and domestication of petroleum-degrading in-site microorganisms in the Permafrost Regions as well as investigation of petroleum degradation efficiency.In the low-temperature condition simulated in relation to the qinghai-tibet plateau,the diesel content of the liquid samples changed from 835 mg to 304 mg after 17 days,and the diesel degradation rate was 63.59 %.After 15 days,the oil contect wasreduced from 455 mg to 312 mg and the degradation rate was 31.4%.The degradation rate of the oil was 54.73 % after 30 days.The Biodegradation rules of diesel and oil conformed to a frist-order reaction,and the kinetic equation is-dc/dt=kt,achieving the fitting correlation high.(3)The single-factor studies of electron acceptors and surfactants showed that the addition of an appropriate concentration of electron acceptors and surfactants could significantly improve the biodegradation of diesel and oil.Tw-80,APG,and H2O2 were selected as auxiliaries to improve the biodegradability of petroleum.An orthogonal test was designed to investigate synergistic effects of improving on the degradation of diesel.The study showed that the optimal addition amount can be achieved through optimization of the orthogonal test.That is,when APG,Tw-80,and H2O2 were added at 300 mg/L,150 mg/L,and100 mg/L,the degradation rate of diesel was the highest.It is 67.13 %.(4)The experiment of soil bioremediation polluted by the diesel showed that isolation of Petroleum degrading bacteria in the laboratory have a good degradation effect.By adding N and P sources in the soil,the physical and chemical structure of the soil can be effectively improved,and the microbial growth and metabolism environment can be optimized.Through the addition of sawdust and plowing in the soil degradation experiments,the degradation rate of diesel was significantly increased.The degradation rate of diesel at 10 ? after 60 days was close to 50 %.Through this study,the feasibility of bioremediation of petroleum-contaminated soil in the permafrost zone was further verified,which provides theoretical support for bioremediation of petroleum-contaminated soil.