Research team of Hu Xiaoke from Yantai Coastal Zone Institute of Chinese Academy of Sciences made progress in microbial degradation mechanism of nitroaromatic pollutants

Nitroaromatic compounds are a kind of important chemical raw materials, which are widely used in the production of medicine, pesticide, dye, pesticide and other chemical products Most of these compounds have high toxicity, have the effect of enrichment and amplification in the food chain, and have teratogenic, carcinogenic, mutagenic properties on human body, which seriously threaten human health 2,6-dibromo-4-nitrophenol (2,6-dbnp) is a typical halogenated nitrophenol The electron absorption properties of bromine and nitro lead to the decrease of electron cloud density of benzene ring, which makes 2,6-dbnp difficult to react, to be attacked by oxidation, to be degraded, and to endanger the ecological environment and human health for a long time As we all know, microorganisms play a key role in the degradation of organic pollutants However, no microorganism has been reported to be able to degrade 2,6-dbnp Hu Xiaoke, a research team of "marine environment microorganism and Biotechnology" of Yantai Coastal Zone Research Institute, Chinese Academy of Sciences, recently screened a strain of bacteria (cupriavidus sp strain cnp-8) that can use 2,6-dbnp as the sole carbon source, nitrogen source and energy source to grow The team combined genome, transcriptome and RT-qPCR analysis to identify the gene cluster (hnpabcd) involved in 2,6-dbnp metabolism in cnp-8 strain The key enzymes, hnpa, hnpb and hNPC, involved in metabolism were expressed, purified and identified It was found that the FADH2 dependent monooxygenase (hnpa), assisted by the flavin reductase (hnpb), could successively catalyze the denitrification and debromination of 2,6-dbnp to produce 6-bromo-metabenzoquinol, 6-bhq); hNPC catalyzes the ring opening of 6-bhq double oxygenation reaction, and then it is further degraded by maleic acid reductase (hnpd) into the tricarboxylic acid cycle Gene knockout and complementation revealed that hnpa gene was necessary for cnp-8 to degrade 2,6-dbnp This study is the first to report the process and molecular mechanism of microbial degradation of 2,6-dbnp The results were recently published in the international academic journal Journal of hazardous materials (DOI: 10.1016 / j.jhazmat 2018.08.063) The team has been working on the molecular mechanism and remediation of microbial degradation of organic pollutants for a long time In the early stage of the team, the molecular mechanism of microbial degradation of 2-chloro-5-nitrophenol and 3-methyl-4-nitrophenol and other typical nitrophenol pollutants was revealed at the molecular, biochemical and genetic levels for the first time The team developed an independent intellectual property pollutant remediation agent, and carried out micro bioremediation on three organophosphorus pesticide degradation products: 4-nitrophenol (methyl parathion product), 3-methyl-4-nitrophenol (fenitrothion product) and 2-chloro-4-nitrophenol (isochlorothiaphos product) The remediation agent can completely degrade three nitrophenol pollutants (50) in 8-16 days Ppm) In addition, molecular ecology studies have shown that bioaugmentation does not affect indigenous microbial ecosystems The team's recent series of research results filled in the gaps in the metabolism mechanism of typical nitrophenol pollutants in the coastal zone, such as 2,6-dibromo-4-nitrophenol, 2-chloro-5-nitrophenol and 3-methyl-4-nitrophenol, revealed the environmental attribution of these pollutants, and provided theoretical basis and technical support for the remediation of such highly toxic pollutants Researcher Hu Xiaoke is the corresponding author of the above series of studies, and assistant researcher min Jun is the first author The research is supported by the National Natural Science Foundation, the national key research and development plan, the cutting-edge focus of the Chinese Academy of Sciences, Yantai science and technology development plan, and the open fund of the National Key Laboratory of microbial metabolism Figure 1 Molecular mechanism of microbial degradation of 2-chloro-5-nitrophenol (source: j.hazard Mater.) Figure 2 Molecular mechanism of microbial degradation of 3-methyl-4-nitrophenol (source: j.hazard Mater.)