Microbial Remediation And Community Analysis Of Phenanthrene-copper Composite Polluted Soil

Polycyclic aromatic hydrocarbons and heavy metals are two major contaminants in contaminated soils.They are easily deposited in the soil and harm the soil environment,affecting seriously the survival of animals,plants and microorganisms in the environment seriously.Polycyclic aromatic hydrocarbons and heavy metals can enter the human body through multiple pathways and endanger human health.The toxicity of polycyclic aromatic hydrocarbons and heavy metals complex pollution is far greater than the sum of the toxicities produced by a single source of pollution.However,most of the domestic and overseas researchers study single pollution sources or organic matter-organic compound pollution and heavy metal-heavy metal compound pollution.There are few researches on organic compound-heavy metal compound pollution.Therefore,it is an important reality for the remediation of polycyclic aromatic hydrocarbons and heavy metals contaminated soil.In this paper,phenanthrene and typical heavy metal copper were used as the representative pollutants,and nutrients and modifiers were used as additives to microbially remediate phenanthrene-copper contaminated soils,and high-throughput sequencing methods were used for microbial remediation.During the process,the community structure of the microorganisms in the soil was analyzed,and then the copper-tolerant phenanthrene-resistant strains were screened and separated in the soil during the process of compound contaminated soil remediation.The results of my investigation are as follows:(1)After the determination of relevant indicators such as content of hydrocarbon decomposing bacteria,the activity of soil enzyme,different forms of copper,and residual phenanthrene in contaminated soil samples during the process of microbial remediation,found that the greater the amount of organic waste,the higher content of hydrocarbon degrading bacteria(up to 9.58×108cfu/g)we get,the more soil urease(up to 1.7ugNH3-N·kg-1·h-1),higher dehydrogenase activity(up to 85.3ugTPF·g-1·h-1),and higher conversion rate of soluble copper to other forms(the highest is 60.8%),the higher the degradation rate of phenanthrene(up to 92.85%).(2)Soil samples for microbial remediation were subjected to high-throughput sequencing to analyze the changing rule of microbial community structure during the process of microbial remediation.It was found that Proteobacteria(up to 53.48%)have the largest proportion of the Phylum,Alphaproteobacteria(up to 38.8%)have the largest proportion of the Class,Sphingobacteriales(up to 39.49%)have the largest proportion of the Order.Chitinophagaceae(up to 33.29%)have the largest proportion of the Families,and Arachidicoccus(up to 30.61%)have the largest proportion of the Genus during the entire remediation process.(3)We used conventional plate culture methods to screening and isolation of copper-tolerant phenanthrene-resistant strains during Philippine-copper contaminated soil remediation.Enriched by multiple selective medium,separated and purified by LB medium,five strains of copper-tolerant phenanthrene were isolated and named as P-4,P-6,P-7,P-11,and P-15.The 16S rDNA sequence was used to test them.P-4,P-7 and P-15 were identified as Pseudomonas sp.,P-6 was identified as Bacillus sp.,and P-11 was identified as Acinetobacter sp..(4)It was found that P-6 and P-11 have better degradation effect on phenanthrene and better copper resistance by exploring the potential ability of five isolated strains to degrade phenanthrene and their effect on phenanthrene degradability under different copper concentrations.