Tetracycline degradation by Klebsiella sp. strain TR5: Proposed degradation pathway and possible genes involved.
Tetracycline degradation by Klebsiella sp. strain TR5: Proposed degradation pathway and possible genes involved.
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DOI：
10.1016/j.chemosphere.2020.126729
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发表时间：
2020-04
期刊：
影响因子：
8.8
通讯作者：
Zhifeng Yin;Dan Xia;Min Shen;Dewei Zhu;Haijie Cai;Meng Wu;Qiurong Zhu;Yijun Kang
中科院分区：
文献类型：
--
作者：
Zhifeng Yin;Dan Xia;Min Shen;Dewei Zhu;Haijie Cai;Meng Wu;Qiurong Zhu;Yijun Kang
四环素（TC）废水的生物处理需要高降解效率的微生物。采用多次富集培养的方法，从某大型肉鸡养殖场的鸡粪混合物中分离到一株TC降解菌TR 5，经16 S rRNA基因测序和生化特性鉴定，该菌株为肺炎克雷伯氏菌（Klebsiella pneumoniae）。通过单因素试验结合响应面法，在优化条件下，菌株TR 5对初始浓度为200 mg/L的TC降解速度较快，36 h内降解率可达90%以上。菌株TR 5在培养一天以上的时间内即可对TC进行解毒，且产生的毒性产物明显降低。根据8种可能的降解产物提出了3条降解途径。含有TR 5质粒的质粒载体获得了TC降解能力，表明TC降解基因位于该质粒上。pYK 5的全序列分析表明，异构酶，氧化还原酶和转移酶编码基因被发现，并推断参与TC降解。TR 5可能不能完全降解TC，它可以通过甲酰谷胱甘肽水解酶编码基因的作用利用TC衍生的一些含碳化合物。研究结果表明，菌株TR 5是一种很有前途的废水处理剂，其降解TC的相关基因值得进一步研究，以开发酶制剂。
Microorganisms with high tetracycline (TC) degradation efficiencies are required for biological processes for TC-containing wastewater treatment. With multiple enrichment cultures, a TC-degrading strain TR5 was isolated from chicken manure mixture in a large broiler farm, which was identified asKlebsiella pneumoniaeby 16S rRNA gene sequencing and biochemical properties. Strain TR5 could degrade TC quickly (∼90% within 36 h) with the initial TC concentration of 200 mg/L under optimized conditions via single-factor experiment coupled with RSM. Strain TR5 could detoxify TC and generate much less toxic products as long as cultured more than one day. Three TC-degrading pathways were proposed based on 8 possible products. A transformant containing a plasmid from TR5 acquired TC-degrading ability, indicating that TC-degrading genes were located on this plasmid. Complete sequencing of pYK5 showed that isomerase-, oxidoreductase-, and transferases-encoding genes were found and were inferred to be involved in TC degradation. TR5 may not degrade TC completely and it can utilize some carbon-containing compounds derived from TC via the effect of formylglutathione hydrolase-encoding gene. Our findings showed that strain TR5 could be a promising agent for wastewater treatment, and genes involved in TC degradation are worthy of further investigations for enzyme preparations development.