Study On Micro-biological Degrading Dynamics And Affecting Factors Of Tylosin Residue In Pharmaceutical

The occurrence of pharmaceutical residues, especially antibiotics in environment have received considerable attention in recent years.Bioremediation is a promising approach to reduce environmental contamination. The objective of this study was to evaluate the efficiency of a tylosin-degrading strain in reducing tylosin residue in pharmaceutical waste, discussing the physiology and biochemsitry of the stain, characteristics of tylosin degradation kinetics, biodegradation of tylosin by enzyme obtained from the strain, the influences of the various parameters and the ecotoxicity of tylosin degradation products were also discussed.The research purpose is to provide valuable information on dealing with tylosin residue in pharmaceutical waste and resource utilization. The results were given as follows:(1) A tylosin-degrading strain named TS1was isolated from the soil deposited by tylosin pharmaceutical waste. The cells of the isolate were Gram-negative rods, the isolate was identified as Burkholderia vietnamiensis based on analysis of16S rDNA sequence, Genebank ID is KC282371. B. vietnamiensis has the ability of resistance to alkali, and B.vietnamiensis coould grow vigorous even under the conditions as follows:pH5～11, temperature20-50℃, in addition, B.vietnamiensis had capacity to grow in3%salty medium.(2) The tylosin degradation by B.vietnamiensis followed a first-order kinetics model. For tylosin with the initial concentrations of50,100,200,300,400,500mg/L, the degradation equations were In c=-0.4078t+4.043. In c=-0.4496t+4.8416, In c=-0.4069t+5.4932, In c=-0.4174t+5.9766, In c=-0.4233t+6.2483, and In c=-0.342/+6.4618, and the half-life periods (t1/2) were1.69,1.54,1.70,1.66,1.64,2.03d, respectively.(3) When the peptone or NH4’-N was used as co-metabolism substrate with tylosin, B.vietnumiensis could degrade above99%of tylosin in medium with an initial concentration of300mg/L after incubation for7d. The kinetics equations of degradation were In c=-0.417t/+5.9766and In c=-0.3719t+6.0133, and t1/2were1.66and1.86d, respectively. However, only66.7%of tylosin was degraded by the strain TS1after10d of incubation when glucose was selected as co-metabolism substrate, and t1/2was also extended to6.44d. suggesting that glucose may have a negative action on the tylosin degradation by B.vietnamiensis.(4) The characteristics of crude enzyme of B. vietnamiensis were primary studied. It was showed that the In c and degrading time (t) followed a logarithmic curv; the t1/2increased as the concen-tration of tylosin increased; the t1/2were less than1h when the concentration of tylosin were less than600mg/L, high concentration of tylosin inhibited the enzyme degradation.(5) Tylosin at the highest test concentration of2000mg/L, which was degradated by B.vietnamiensis, nevertheless, its degradation products hardly had any effect at environmentally. It indicated that the products of the tylosin by B.vietnamiensis were friendly to environment.