Study On Anaerobic Degradation Of Estradiol By Microflora In Typical Mangroves Of China

With the development of society and the intensification of industrialization,the overuse of hormone drugs leads to the increasingly serious pollution of estrogen in the ecological environment,which affects the balance of the whole ecosystem and endangers human health;How to remove environmental estrogens is a hot research topic.Bioremediation,as the most effective technology to remove environmental estrogens and carry out environmental remediation,is highly praised by the majority of researchers.Mangrove wetland ecosystem is located in the intertidal coastline,which can effectively absorb pollutants.There are abundant microbial resources in the sediments,which are very important for the removal of environmental estrogens and environmental remediation;At present,there are few studies on the anaerobic metabolism of estrogen by microorganisms.In this study,seven typical mangrove regions(Hainan,Hong Kong,Shenzhen,Beihai,Fangchenggang,Yunxiao,Zhanjiang)in China were selected as the research objects,and the sediment samples were collected and subcultured under the stress of estradiol in anaerobic environment.16 S r RNA gene high-throughput technology,Illumina high-throughput metagenome sequencing technology and Bioinformatics were used,The main results are as follows:1)Based on the in situ 16 S r RNA gene high-throughput analysis,the environmental parameters of the bottom sediments of seven mangrove sites were determined.It was found that the flora was most affected by oxidation-reduction potential(ORP)and estriol(E3);At the phylum level,Firmicutes was the main flora associated with E2 and E1;The main microflora affected by E3 and temperature were Euryarchaeota,Chloroflex I and actinobacteria.The concentrations of four main estrogens in the bottom sediments of mangroves were detected.Compared with the concentrations of estrogens in the surface sediments of mangroves,the bottom sediments(anaerobic layer)were the storage layer of steroids.2)Under anaerobic conditions,the sediments of seven typical mangrove sites were subcultured under estradiol stress.Based on 16 S r RNA gene high-throughput analysis,it was found that the number of OTU in the microbial community structure before and after acclimation was decreasing,and the structure and abundance of anaerobic bacteria were also changing;After the fourth and fifth times of stress subculture,the flora structure of each site has basically reached stability.At the phylum level,there was no significant difference in the colony structure among the seven sites.Proteobacteria was the main species,and its abundance increased from30% to 70% or even more than in situ.At the genus level,Paracoccus in Hong Kong and Hainan sites were significantly enriched under E2 anaerobic stress,accounting for60%-70%;In Fangchenggang and Shenzhen,hyphomycium is the main species,while in Zhanjiang,Marinobacter is the main species.Furthermore,lefse was used to compare and analyze the flora before and after E2 anaerobic acclimation.It was found that with the passage of acclimation time,the species of flora related to E2 anaerobic transformation were fewer and fewer,but the function was stronger.3)Metagenomic sequencing and comparison based on COG and KEGG databases showed that the functional genes related to transcription,coenzyme transport and metabolism were enriched and increased after anaerobic acclimation with E2 as the sole carbon source,while they were closely related to carbohydrate transport and metabolism,biosynthesis of secondary metabolites and metabolism The abundance of genes related to transport and catabolism decreased significantly.The correlation analysis of functional genes and the mapping of synergetic metabolism network showed that the anaerobic metabolism/transformation of estrogen was closely related to amino acid metabolism and vitamin metabolism;Furthermore,the anaerobic co metabolism model of E2 was constructed and it was found that six mags bacteria participated in the co metabolism of E2.Therefore,it is speculated that the anaerobic metabolism of mangrove microbial estrogens is a multi-step process,which requires the cooperation of a group of symbiotic bacteria.Through the above studies,we explored the functional flora related to estradiol metabolism in different mangroves,and preliminarily analyzed the pathway of estradiol anaerobic metabolism,which provided a theoretical basis for estrogen bioremediation.