| With the vigorous development of the crude oil industry worldwide,crude oil and its products are widely used.However,the accidental leakage of crude oil in the process of exploitation,transportation,storage and processing,which brought about pollution of the ecological environment.In particular,water and soil pollution are becoming increasingly serious,endangering human health and ecological balance.It is essential to eliminate oil pollution and repair the ecological environment.There are three technologies commonly used to solve the problem of oil pollution,bioremediation technology,physical recovery technology,and chemical treatment technology.Bioremediation technology has more development prospects,and it is considered to be a highly efficient,safe,economic,and non-secondary pollution remediation technology.Isolating and screening crude oil degrading strains from oil contaminated soil,constructing efficient crude oil degrading strains,and researching the degradation characteristics of microorganisms on crude oil pollutants,which are the basic conditions for the application and development of bioremediation crude oil pollution technology,and also have important practical significance.A total of 123 individual strains were isolated from crude oil through enrichment culture and screening from Xinjiang oil contaminated soil.Thirty different strains were selected according to the morphology of the colonies,and their species were determined by16 S rRNA gene sequencing to construct a phylogenetic tree.Analyzing and measuring the degradation characteristics of thirty individual strain by ultraviolet spectrophotometer and gas chromatography-mass spectrometry(GC-MS),and highly efficient crude oil degrading strains were screened out.Researching the degrading strains of aromatic hydrocarbon compounds naphthalene in crude oil components,as well as efficient degrading strains of salicylic acid and catechol.Through the establishment of a division of labor and cooperative degradation group,to achieve the purpose of effectively improving the degradation rate of naphthalene,with a view to biological remediation of oil contaminated soil provides a certain data reference and application basis.The specific contents and results of are as follows:(1)According to the standard measurement,the water content of the oil contaminated soil in the surface,middle and lower layers was 3.99%,24.35% and 8.55%,the oil content was 4.57%,12.43% and 22.96%,respectively.The four components ofcrude oil include saturated hydrocarbons,aromatic hydrocarbons,non-hydrocarbons,and asphaltenes.The measured saturated hydrocarbons were 35.20%,aromatic hydrocarbons were 44.64%,non-hydrocarbons were 4.63%,and asphaltenes were 15.54%.(2)Through 16 S rRNA specific primer PCR amplification,gene sequence comparison and phylogenetic tree construction of the thirty strains,the species were identified as Lysinibacillus,Achromobacter,Pannonibacter,Ochrobactrum,Pseudomonas,Dietzia,Delftia,Microbacterium,Rhodococcus,Acinetobacter,Bacillus,Kocuria,Halomonas,Mycoplana,Staphylococcus,Pantoea,Exiguobacterium,of which Pseudomonas accounted for 23.33% of the total.Strains at the Phylum level included Firmicutes,Actinobacteria,and Proteobacteria.Strains at the Class level included Bacilli,Alphaproteobacteria,Betaproteobacteria,Gammaproteobacteria,Actinobacteridae.(3)Using crude oil as the sole carbon source to culture and screen highly efficient degrading strains.GC-MS was used to measure and calculate the degradation rates,and the gas chromatograms of thirty strains were analyzed.There were twelve strains with degradation rate over 50%,A15,A23,A24,A25,A44,A46,A50,A52,A56,A58,A62,A68.Among them,the number of Pseudomonas accounted for 25%.The highest degradation rate was 90.2%,which belonged to strain A44 Pseudomonas nitritireducens.The lowest degradation rate was 7.1%,which belonged to strain A1 Lysinibacillus fusiformis.(4)Using naphthalene,salicylic acid and catechol as the sole carbon source to culture and screen highly efficient degrading strains.GC-MS was used to measure and calculate the degradation rates of naphthalene.And ultraviolet spectrophotometer was used to measure and calculate the degradation rates of salicylic acid and catechol,respectively.Selecting one strain of each group with excellent degradation ability,and the metabolites of naphthalene degradation group included salicylic acid and catechol.The naphthalene degradation rate of A46 Pseudomonas nitritireducens was 60.74%,the salicylic acid degradation rate of A32 Rhodococcus pyridinivorans was 58.15%,and the catechol degradation rate of A11 Pseudomonas stutzeri was 72.22%.The three strains were mixed12 days for cultivation to degrade naphthalene by "co-metablism",the cell density and gas chromatogram of naphthalene degrading strain A46 were measured.Compared with the individual strain group,the cell density of A46 in mixed strains group did not reduced but increase.The naphthalene degradation rate of individual strain group was 60.74%,and that of mixed strains group was 89.40%.The results show that "co-metablism" degradation caneffectively improve the naphthalene degradation ability of microorganism and offer a reference for further research on bioremediation of crude oil pollution.Figure [ 23 ] table [ 16 ] reference [ 81 ]... |
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