Tylosin is widely used in livestock; however, the release of tylosin through animal manure can cause serious environmental problems. In this study, a new tylosin-degrading strain, TYL-T1, was isolated. Its phylogenetic similarity to Klebsiella oxytoca was found to be 99.17 %. TYL-T1 maintained good growth at 40 °C over a broad pH range (4.0-10). TYL-T1 degraded 99.34 % of tylosin in 36 h under optimal conditions (tylosin initial concentration: 25 mg/L, pH: 7.0, and temperature: 35 °C). After LC-MS-MS analysis, a new degradation pathway for tylosin was proposed, including ester bond breaking of the macrolide lactone ring, redox reaction, and loss of mycinose and mycarose. Based on a transcriptome analysis, 164 genes essential for degradation were upregulated through hydrolysis and redox of tylosin. Among various transferases, lipopolysaccharide methyltransferase, glycogen glucosyltransferase, and fructotransferase were responsible for tylosin degradation. The present study revealed the degradation mechanism of tylosin and highlighted the potential of Klebsiella oxytoca TYL-T1 to remove tylosin from the environment.
Keywords: Antibiotic resistance genes; Degradation pathway; Klebsiella oxytoca; Transcriptome analysis; Tylosin.
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