Tetracycline degradation by Klebsiella sp. strain TR5: Proposed degradation pathway and possible genes involved

• Published in: Chemosphere (Oxford) 2020-08, Vol.253, p.126729-126729, Article 126729
• Main Authors: Yin, Zhifeng, Xia, Dan, Shen, Min, Zhu, Dewei, Cai, Haijie, Wu, Meng, Zhu, Qiurong, Kang, Yijun
• Format: Article
• Language: English
• Subjects: Degradation; Klebsiella; Pathway; Plasmid; Tetracycline
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.126729

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 as Klebsiella pneumoniae by 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. •TR5 degrades high concentration of TC quickly (∼90% within 36 h).•TR5 detoxifies TC and generates less toxic products.•TC-degrading pathways are proposed.•Possible genes involved in TC degradation are discussed.