Study On Microbial Degradation Pathway And Degradation Products Of Tylosin Residue In Pharmaceutical Waste

Tylosin is a macrolide antibiotic used exclusively in veterinary medicine and feed additives, and it is greatly promoted the development of husbandry. But it also derived some negative consequences. The most attended problem is that increasing of tolerance to bacteria brings risk to human and animal health and ecological environment. The current research focus for the tylosin mostly concentrated in honey, milk, fishery products and animal tissues content analysis of tylosin residues. Few researches are available about residue analysis in the environment especially in pharmaceutical waste. Microbial degradation and degradation mechanism of tylosin, is still not been reported. The paper takes the tylosin residue in pharmaceutical waste as research object, the results were given as follows.(1) To develop a method for the determination of tylosin residue in pharmaceutical waste using solid phase extraction (SPE)-high performance liquid chromatography with a UV detection system. Tylosin in pharmaceutical waste was extracted using methanol, defatted with hexane, purified on a C18-SPE column, and then determined using C18-reversed-phase column with external standard. The mobile phase was acetonitrile-0.02mol·L-1phosphate buffer and the flow rate was1.0mL·L-1with isocratic elution. The tylosin concentrations within the range of0.1-100mg·L-1exhibited a better linearity. The recoveries at spiked concentration of16,20,24mg·L-1were in the range of92.9%-107.1%, and the relative standard deviations were2.4%-4.1%. The detection limit was0.05mg·L-This method is simple, rapid, and accurate for the detection of tylosin residue in pharmaceutical waste and feed.(2) B.vietnamiensis could effectively degrade concentration of tylosin pharmaceutical waste (83.33mg·L-1) and the tylosin degradation was97.70%after incubation5days. Compared with the degradation rate only53.46%before domestication, it had a significant degradation effects to tylosin after domestication. Tylosin could be completely degraded after1hour. Through the use of UV-visible spectrophotometers for analysing before and after the microbial degradation of tylosin. preliminarily discussed that generating new degradation product after degradation.(3) The degradation products of tylosin are isolated with thin layer chromatography (TLC), and the carbinol/ethylacetate is used as developing solvent. The products can be separated into two types when the ratio is adjusted1:6(V/V). The degradation products are still chromogenic under ultraviolet lamp after developing. This indicates that the conjugated system still exists in the tylosin molecular structure.(4) Through the use of preparative HPLC and MS for analyzing microbial degradation products of tylosin, a preliminary study was discussed about the degradation pathway of tylosin of B.vietnamiensis. The possible ways are:tylosin A was firstly desugared by B.vietnamiensis to form tylosin B, and then lactone bond and aldehyde group in structure were possibly hydrolyzed and reduced to generate two new of degradation products.