Abstract: Intracellular crude enzyme solution of Klebsiella oxytoca (TYL-T1) was used as a starting material. The degradation characteristics of tylosin by TYL-T1 intracellular crude enzyme solution were studied. When the degradation system contains 25 mg/L of tylosin, the optimal degradation conditions were pH 7.0, 45 ℃, and 2.5 mg intracellular crude enzyme, resulting in 94.33% degradation rate within six hours. The addition of heavy metal ions such as Co2+, Fe2+, and Mn2+, respectively, promoted tylosin degradation. The process of tylosin degradation conformed to the first-order kinetic reaction model. The degradation rate constant was 0.714 9 h-1, the half-life was 1.0 h, and the maximum reaction rate was 22.58 mg/(L·h). The degradation products did not inhibit the growth of indicator bacteria, indicating that intracellular crude enzyme solution could eliminate the ecological toxicity of tylosin. Therefore, the intracellular crude enzyme solution of Klebsiella oxytoca might become an alternative tool to degrade tylosin.

Key words: tylosin, Klebsiella oxytoca, intracellular enzyme crude solution, degradation kinetics, product toxicity