Denitrifying Microbial Community Structure and bamA Gene Diversity of Phenol Degraders in Soil Contaminated from the Coking Process
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Phenolic compounds are the dominant pollutants in soils contaminated by the coking industry. Ring opening by the hydroxylase gene (bamA) is the key step in the benzoyl-CoA degradation pathway under anaerobic conditions, and a broad spectrum of microorganisms possesses this functional gene, including denitrifiers. The present study analyzed the community structure of denitrifying bacteria and the diversity of the bamA gene for mixed cultures enriched from soil collected at a coking industrial site and then grown under nitrate-reducing conditions on phenol or p-hydroxybenzoate (4HBA), a key intermediate product of anaerobic phenol degradation. Illumina sequencing of the 16S rRNA gene showed different bacterial compositions between the two cultures. The dominant phyla were Proteobacteria, Armatimonadetes, and Planctomycetes in the phenol culture and Proteobacteria and Bacteroidetes in the 4HBA culture. Phylogenetic analysis further demonstrated that bamA genes were associated with four clusters of bacteria, three of known bacteria and one of uncultured bacteria. The diversity of the bamA gene differed from that reported in anaerobic aromatic degradation cultures, suggesting that these enriched cultures may contain new strains unique to coking-contaminated soils. The present study further validates the potential application of this functional gene as a marker for anaerobic biodegradation processes in enrichment cultures from contaminated soil.
KeywordsAzoarcus bamA gene Denitrifiers Illumina sequencing p-Hydroxybenzoate Phenol
Jianwei Wang is acknowledged for the helpful discussion in the design of the study and for the help with culture setting up. Jin Liu and Jingyi Fu are both thanked for collecting soil samples from the coking plant.
This study was supported by the Science and Technology Planning Project of Guangdong Province (No. 2017B030314092), Open Fund of Key Laboratory of Eco-geochemistry, Ministry of Natural Resources (No. ZSDHJJ201804), Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (No. 2016146, 201802026), the Scientific and Technological Project of Shanxi Province (No. 2015021119), and the National Natural Science Foundation of China (No. 51378330, 51408396).
Compliance with Ethical Standards
The authors declare that they have no competing interests.
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