Study On The Degradation,Adsorption And Migration Of Fusarium Solani GHP1FB In Phenanthrene Pollution Remediation

polycyclic aromatic hydrocarbons(PAHs),an important group of persistent organic pollutants,are of great concern because of their wide pollution range,wide distribution and potentially strong toxicity.Microbial remediation technology is one of the most important methods for remediation of PAHs in the environment,with low cost and no secondary pollution.The establishment of microbial co-culture system can enhance the biodegradation rate and bioavailability of PAHs,and improve the disadvantage that a single microorganism is difficult to achieve the ideal effect in the actual site repair.Therefore,in this paper,the soil of the central partition zone of the expressway in Henan Province was selected as the soil for screening bacteria,the characteristics of PAHs pollution were analyzed,the ecological risk of PAHs was assessed,and the sources of PAHs were discussed.A fungus Fusarium solani GHP1FB was screened from soil polluted by highway with phenanthene as the only carbon source,aiming to study its degradation characteristics and absorption and storage capacity of phenanthene under liquid culture conditions.Meanwhile,the application of Fusarium solani GHP1FB on the migration and transportation of degrading bacteria was also discussed.It provides a theoretical basis for improving microbial remediation of soil organic pollution.The results are as follows:(1)In order to analyze the pollution status and potential risk of polycyclic aromatic hydrocarbons(PAHs)in the central separate belt of expressways,11 soil samples were collected from 3 expressways in Henan Province,and the amounts of 16 PAHs were determined.In addition,the pollution characteristics and ecological risk of PAHs were also evaluated.The results showed that the total PAHs content in the central separate belt of expressways soils ranged from 5 253.33 to 65 072 μg·kg-1,with a mean value of 19873.μg·kg-1.Among them,low and high-ring PAHs accounted for 42.46%and 57.54%,respectively.In addition,sampling sites 2 and 7 were more polluted by PAHs than the other 9 sampling sites.The ecological risk assessment results indicated that the soils in the central separate belt of expressways are polluted by PAHs,with 72.72%of the polluted soils posing medium or higher ecological risks.The health risk assessment showed that the soil posed a greater risk of carcinogenicity to both children and adults,and the main exposure routes were skin contact and ingestion.The characteristics of PAHs component combined with the source analysis showed that low-ring PAHs are mainly from diesel engine combustion of heavy vehicles,and highring PAHs are from gasoline engine combustion of small cars.The correlation analysis indicated that the PAHs,especially high-ring PAHs,were significantly positively correlated with soil organic matter and negatively correlated with cation exchange capacity,total nitrogen,and pH.(2)Using Phenanthrene as the sole carbon source,a filamentous fungus was screened from the soil of the central partition zone of the highway.It was identified and compared as the hydrophobic fungus Fusarium solani,named 1FBFusarium solani.Studies on the absorption,storage and degradation characteristics of 1FB for phenanthrene in liquid culture showed that:Due to the lack of nutrients in the culture system with low initial concentration,the degradation of phenanthrene was less in the culture cycle(0-15 d),and the adsorption effect was better than the degradation effect.In the early stage of culture(0-1d),the biological adsorption was the main,and in the late stage of culture(3-7 d),the biological degradation was the main.The study on the dissipation and transport kinetics of phenanthrene by 1FB showed that the rate of phenanthrene transported from solution to intracellular(KinS/Vout)was greater than the rate of phenanthrene discharged from inside and outside the cell to solution,and the constant of phenanthrene dissipation rate in intracellular(Kdin)was also greater than that in extracellular(Kdout),indicating that phenanthrene transported from solution to intracellular(Kdout)was more likely to occur,and the adsorption capacity of phenanthrene by 1FB was greater than the degradation capacity.(3)The diffusion dish experiment showed that fungi and bacterial migratio n promoted the degradation of phenanthophene in the co-culture system.The d egradation rates of phenanthophene contaminated soil with an initial concentrati on of 50 mg·kg-1 were up to 91.23%and 91.71%,respectively,after 28 days of XS and FS treatment.High-throughput sequencing results showed that Bacill us,Rhodococcus,Fictibacillus and Streptomyces showed good migratory ability.Fungi including Talaromyces,Aspergillus and Unclassified_f_Pyronemataceae;Fungus-bacteria co-culture is mainly conducted by improving the bacteria gener a in the soil including Bacillus,Rhodococcus,Nocardioides,Streptomyces,Micr ovirga,Arthrobacter and Lysobacter,Fungus including Aspergillus,Neocosmosp ora,Unclassified f Pyronemataceae,Cephaliophora and Fusarium.