| The pollution of polycyclic aromatic hydrocarbons in mine groundwater is mainly caused by the machine lubricants remant,coal and coal gangue.Microbial degradation is the best way to deal with groundwater PAHs pollution.Therefore,in order to ensure the safety of mine groundwater after mine closure,it is necessary to discuss the restoration law and feasibility of microbial community to mine groundwater environment.In the natural environment,microorganisms exist in groups.In this paper,the intermediate-substrate model was used to screen phenanthrene and catechol as target pollutants from contaminated mine sludge.Through the analysis of microbial community diversity in different time periods,the changes of microbial community structure were observed to explore the main ways of degradation of phenanthrene by dominant degradation bacteria.The main contents are as follows:(1)In a mine sludge source strain,screened F-1,F-2,F-3 degradation community,analysis by High-throughput Illumina Miseq sequencing showed the dominated floras were Cupriavidus,Paenibacillus and Bacillus.(2)Degradation of phenanthrene under different conditions: F-1 flora at T=30°C,TDS=3000mg/L and pH=9 the degradation rate reached 97.6%,but sensitive to environmental changes;F-2 flora is suitable for pH=5,TDS=1000mg/L,T=40°C,the degradation rate can be about 60% after 25d;F-3 flora has strong adaptability to pH and T.in the TDS> 1000 mg / L degradation results in more than 45%,preferably of environmental adaptability.(3)Succession of communities under different factors: 16 SrDNA sequencing analysis of colony composition of F1,F-2 and F-3 at 5th and 25 d under different salinity,pH and temperature conditions,respectively,through bacteria The composition of the community explored the changes of dominant genus,and the heat evolution was used to predict the succession of the community through colony structure changes.The conclusion is drawn that the changes in salinity,pH,temperature and certain factors of DO will lead to the succession of microbial communities in different directions;(1)Effect of TDS on the composition of the flora: F-1 and F-3 have obvious effects on the change of TDS,and the change of TDS affects the composition of the dominant degrading genus;F-2 has better adaptability to the change of TDS For the change of mineralization degree,the dominant genus is Pandoraea;(2)pH affects the composition of the flora: F-1,F-3 change the pH of the flora in different directions,the dominant genus is different;F-2 The flora of the bacteria changed to pH.The dominant genus was Proteobacteria,and the dominant genus had good tolerance to pH.(3)The effect of temperature on the composition of the flora: At the initial stage,the dominant degrading bacteria were Enterobacteriaceae.Mainly,after 25 days,at the temperature of 40 ° C and 20 ° C,the composition of the three microflora was similar,mainly based on Pseudomonas,which is more adaptable to the environment.At 30 °C,the F-1 population was It is always based on Enterobacteriaceae,and F-2 and F-3 are always Pseudomonas.(4)The intermediate products and final products were detected by GC-MS.It is speculated that the main pathways of F-1 and F-2 are phenanthrene dioxygenase to form 3,4-dihydroglycol phenanthrene and then oxidized ring-opening to form naphthalene.After the enzymatic oxidation to form an acid anhydride,the degradation of phenanthrene by F-3 is in addition to the oxidation of the enzyme at the 3 and 4 positions,and the monooxygenase at the 9th and 10 th positions to form 9,10-epoxy.The phenanthroline or dibenzofuran is further subjected to enzymatic oxidation to achieve complete ring-opening degradation.The 16 s functional prediction analysis compared the three bacterial degradation pathways and found that the F-1,F-2 and F-3 enzymes were different,which confirmed that the three bacterial groups have different metabolic pathways for polycyclic aromatic hydrocarbons. |
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