| Xinjiang is rich in oil and gas resources,and with the development of resources large of oil pollutants discharged into the soil environment and causing great harm to the fragile ecological environment.Microbial remediation technology has achieved many practical results in application to remediation of oil contaminated soil,but there are still some problems to be solved such as whether the oil-degrading bacteria would adapt to the field environment and whether they will lose their dominant position in competition with indigenous microorganisms during the degradation process.Based on the existing problems,in this paper,the oil contaminated soil in the five oil production areas of Luliang,Huo shaoshan,Cainan,Jixiang and Shanan of Zhundong Oilfield was collected as the material,and the oil degradation bacteria were screened and isolated by liquid enrichment culture from these oil contaminated soil and were identified by 16S r RNA sequencing.High efficiency oil degradation bacteria were identified after liquid shake-flask degradation experiment.Among them,CY2-1 strains from Luliang oil production area has the strong ability to degrade oil and could secrete surfactant.The degradation substrate spectrum of the high efficiency oil degradation strain was identified by GC-MS analysis,on the other hand,the whole genome and transcriptome were sequenced to research the oil degradation potential and up-and down-regulated genes function of this strain,and finally to study genes and pathways related to the degradation of oil pollutants.At last,a preliminary study on the soil remediation characteristics of this strain was carried out by laboratory simulation experiment.The main results of the study are as follows:(1)24 oil degradation strains were isolated from the environmental samples in Zhundong oilfield.The 16S r RNA gene sequencing and BLAST results showed that these oil degradation strains belonged to three phyla Proteobacteria,Actinobacteria and Firmicutes and seven genera Stenotrophomonas,Staphylococcus,Streptomyces,Rhodococcus,Achromobacter,Pantoea and Pseudomonas.Most strains belonged to Pseudomonas.Through the liquid shake-flask degradation experiment analysis,the CY2-1 strain was identified with high oil degradation ability and could secrete surfactant.33 mg oil can be degraded 96.69%in liquid shaking flask within four days.(2)Liquid shaking flask degradation experiments of CY2-1 strain were carried out and the degradation products were analyzed by GC-MS.The results showed that the total ion chromatogram of the degradation of oil samples by degrading strain significantly changed to the control samples,the large molecular weight alkanes in crude oil were degraded to small molecular weight alkanes.The results also showed that there were 47 components in the control sample and only 19 components were detected after degradation,which could degraded the different alkane components and metabolized into H2O and CO2?The relative abundance of eicosane in the degradation component is high,so it is inferred that the eicosane degradation efficiency of the strain is low?(3)The whole genome and transcriptome were sequenced and the results showed the CY2-1 strain genome size was 6256232bp,the GC content was 66.58%,all gene length accounted for about 89.44%in the whole genome and the strain genome coded5861 genes and 513 non-coding RNA.The transcriptome sequencing results showed that the high expression genes were mostly in the same gene cluster,and the genes related to the n-alkanes degradation were highly expressed such as cytochrome p450,integral-membrane alkane monooxygenase and short-chain dehydrogenase and so on.(4)The laboratory simulation degradation experiment showed that CY2-1 strain degraded oil contaminated sand soil with oil content of 2%by 15 days.The soil moisture content decreased from 23%to 2.5%,the oil content was 0.8%,most of the n-alkanes decreased,and the degradation rates of n-hexadecane and n-heneicosane were slow. |
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