Impact Of Microplastic On The Structure And Biodegradation Potential Of PHE-degrading Bacterial Consortium In Coastal Environment

In coastal environment,because of small oil spills or large-scale accidents,oil and oil-related products are ubiquitous and serious pollution.Polycyclic aromatic hydrocarbons(PAHs)such as phenanthrene and anthracene which contained in petroleum is persistent and toxic substance.Besides,microplastic pollution became more and more prominent in the coastal environment.Due to the large specific surface area of microplastic,it can adsorb persistent organic pollutants(POPs),such as polycyclic aromatic hydrocarbons.Microplastic also had serious effect on the surrounding environment.Most studies focused on the accumulation of microplastic in the organism,however,less was known about the impact of microplastic on microbial ecosystem.Bio-degradation is one of the most important ways to remove polycyclic aromatic hydrocarbon,microplastic is likely to affect the degradation of petroleum hydrocarbon components by microorganisms.Therefore,it is important to explore the impact of microplastic on the biodegradation potential of PAHs-degrading bacterial consortium.In this study,the phenanthrene-degrading bacterial consortium MB1 was collected from seawater contaminated with oil pollution in coastal environment,where microplastic pollution is major concern.We investigated the effects of different factors in the coastal environment on the biodegradation potential of PAHs-degrading bacterial consortium,and the effects of microplastic on the structure and biodegradation potential of PAHs-degrading bacterial consortium was further investigated.The main results were as follows:(1)Obtaining salt-tolerant and high-efficiency phenanthrene-degradation bacterial consortium in coastal environment: the salt-tolerant phenanthrene-degradation bacterial consortium MB1 was obtained by repeated enrichment,and the removal efficiency of 40 mg/L phenanthrene was 85 % after 6 days.The further study of the composition of the community showed that Alternomonnas,Prochlorococcus and Rhodovulum were confirmed as the major group.(2)The effects of different factors in the coastal environment on the biodegradation potential of PAHs-degrading bacterial consortium: when the initial concentration of phenanthrene was 40 mg/L,the degradation efficiency was increased with the increase of temperature in the range of 10-40 ?,but when the salinity of the medium increase,the removal efficiency decreased.When the p H was 8,the removal efficieny was as high as 78.67 %.The results showed that the removal efficiencies of PHE were the highest when temperature=40 ?,p H=8,the salinity of MSM was 0.5 % and the initial concentration of phenanthrene was 40 mg/L,respectively.(3)Microplastic particles can adsorb a small amount of phenanthrene and can slightly promote PHE biodegradation.On the fifth day,compared to the control,the biodegradation efficiency increased 14.42 %.Compared to the control(85.23 %),PHE was totally degraded on the sixth day in the presence of microplastic.SEM images further showed that more filamentary materials existed with microplastic,which was beneficial to the degradation of phenanthrene by microorganisms.(4)The impact of microplastic on the community structure: The impact of microplastic on the community structure was analyzed by Illumina sequences.On the sixth day,the dominant genus changed significantly with the addition of microplastic,and the phenanthrene-degradation bacteria Glaciecola was confirmed as the major group in the community,while Rhdovulum was dominant in the control group.The results indicated that microplastic could change the community structure of PAHs-degrading bacterial consortium,which may affect the biodegradation of the contaminant in the coastal environment.