Isolation And Degrading Characteristics Of Oxytetracycline Degrading Bacteria

Oxytetracycline is one of the best sale antibiotics, and is widely used in the animal husbandry. The massive use not only resulted in residue of OTC in the environment, but also can threat the ecological environment .The technology of biodegradation has developed rapidly in recent years,and it has become one of the most effective bioremediation methods.The aim of the study is to establish the screening model of the highly effective degeneration bacterium and research degeneration characteristics of the strain.A high performance liquid chromatography (HPLC) method was developed for determination of Oxytetracycline (OTC) in the medium.Mcllvaine buffer was used for extracted Oxytetracycline from the medium. Mixture of KH2PO4 (0.05mol/L) and ethylacetate(16:84,V/V) was used as mobile phase in the HPLC analysis.The recoveries of Oxytetracycline ranged from 86.95%~91.68% in medium, the coefficients of variation of OTC ranged from 2.20%~3.70% and 4.10%~6.10%, and the limit of quantitation (LOQ)of OTC was 0.01mg/L.A highly effctive screening model was built,in which enrichment was condueted by adding a definite Oxytetracycline into the innutriment medium. By using direct spreading method,five strains of bacteria were isolated from soil,among which one strain showed the Oxytetracycline degradation ability and which was named as 2# strain. The strain was identified as Bacillus cereus.To study its degeneration characteristics, we take the 2# strain as the goal strain. The 2# strain in pH7.0, temperature 35℃, when the substrate concentration was the 50mg/L,and volume of medium was 80mL, can maintain a higher degeneration speed. Adding carbon and nitrogen enhanced the strain to degenerate the Oxytetracycline in medium. By adding 0.5% soluble starch in the medium, the degeneration rate of the 2# strain reached 79.48% in the 50mg/L Oxytetracycline solution for 3 days. By adding 0.5% yeast extract in the medium, the degeneration rate of the 2# strain reached 87.65%. The metal ions have a significant effect on Oxytetracycline degeneration speed of the strain. In the study, the influence of 9 ions were investigated. The result showed that 0.1% Fe3+ and Zn2+ enhanced the strain to degenerate Oxytetracycline, degeneration rate were 84.79% and 80.31% respectively.At the same time, the experiment aslo studied degeneration of 2# strain to the Doxycycline in the same situation. The result indicated that the strain didn't show degrade ability to the Doxycycline.