Bacterial Community Structure And Bama Gene Diversity Of Phenoldegrading Under Anaerobic Denitrifying Conditions In Coking Contaminated Soil

Phenol and its derivatives are typical organic pollutants produced by the coking industry and have the characteristics of high mobility,high toxicity,and great harm.The research on the microbial community structure and degradation effect of phenol and its derivatives is an important issue in the remediation of coking contaminated soil.In this study,the biodegradation of phenol(Phe)or its core intermediate p-hydroxybenzoate(4HBA)and the nitrate-reducing process were analyzed in Taiyuan coal gasfication coke plant contaminated soil samples by the addition of Phe or 4HBA as the sole carbon source and energy source under denitrifying condition.The structure microbial community and bacteria diversity of anaerobic denitrification of Phe or 4HBA degradation was analyzed by high throughput sequencing.A phylogenetic tree of anaerobic denitrifying degradation of Phe and 4HBA enrichments was constructed in coking contaminated soil to study the diversity of bamA,a benzol ring-opening functional gene.The results of this study will provide a theoretical basis for the further research on the compositional rules and functional gene diversity of anaerobic denitrifying microorganisms in Phe contaminated soil.The main conclusions are as follows:1.In the enrichment cultures,the substrate loss and nitrate loss were synchronization.The actual molar ratios of Phe and 4HBA consumption coupled with nitrate reduction were 1:6.4 and 1:5.3,respectively,which are reasonably similar to the theoretical metrological ratios.2.After 90 days of anaerobic enrichment,the bacterial diversity of the Phe and 4HBA active cultures in coking contaminated soil was reduced compared to the background control.The OTUs shared by 3 soil enrichment samples accounted for 3% of the total OTUs,including Proteobacteria(69%),Armatimonadetes(11%),and Bacteroidetes(8%)It is speculated that this part of microorganisms can exist in the original soil,which can use not only Phe but also 4HBA as electron donor,carbon source and energy.3.The dominant phyla of Phe culture were Proteobacteria,Armatimonadetes and Planctomycetes,while the dominant phyla in 4HBA culture were Proteobacteria and Bacteroidetes.Betaproteobacteria was the dominant class in two kinds of cultures enriched on Phe and 4HBA,with a total relative abundance of 46%.Azoarcus got the highest abundance in the two kinds of cultures,with the relative abundance of nearly 30%.The relative abundance of Armatimonadetes_gp5 in Phe was after Azoarcus,which was very likely to be another dominant genus of Phe degradation under nitrate-reducing conditions in coking contaminated soil.4.The bamA genes in the anaerobic and denitrifying Phe and 4HBA enrichments were dominated by the corresponding genes similar to Azoarcus spp..The diversity of bamA gene is some different from that of anaerobic aromatic degradation cultures that have been studied.It is speculated that coking contaminated soils may contain uncultured or unidentified microorganisms,further validating the potential use of the bamA gene as a marker for the anaerobic biodegradation process in coking contaminated soil enrichment cultures.