高效降解菌Arthrobacter nicotianae ZAF-05对土霉素的减毒效应

  目的  明确1株土霉素(oxytetracycline, OTC)高效降解菌降低OTC生物毒性的效应，为菌株的实际应用提供初步理论依据。  方法  以前期获得的OTC高效降解菌Arthrobacter nicotianae ZAF-05为对象，利用高效液相色谱-电喷雾质谱联用技术(HPLC-Q-TOF-MS)分析了OTC的降解产物。以对OTC敏感的大肠埃希菌Escherichia coli、枯草芽孢杆菌Bacillus subtilis和斜生栅藻Scenedesmus obliquus作为指示生物，评估OTC降解产物的生物毒性。  结果  HPLC-Q-TOF-MS分析发现:经菌株ZAF-05作用后，体系中的高毒性OTC以及其自然水解产物差向异构土霉素(EOTC)含量显著降低，而低毒性的同分异构土霉素(ISO-OTC)含量略有上升。供试细菌和藻类在添加ZAF-05菌株的OTC体系中的生长情况明显好于OTC自然水解的处理和未添加降解菌的阴性对照，且差异极显著(P＜0.01)。与原药和自然水解物相比，经过ZAF-05菌株降解的OTC代谢产物生物毒性大大降低。菌株的降解作用缓解了OTC对斜生栅藻细胞超微结构的伤害，细胞叶绿体及细胞壁受损减轻。  结论  降解菌ZAF-05能降低OTC残留的环境生物毒性，而毒性的降低可能与体系中高毒性物质被转化成无毒或低毒的代谢产物有关。图7表1参26

Reduction of toxicity of oxytetracycline by highly efficient degrading bacterium Arthrobacter nicotianae ZAF-05

  Objective  The objective is to determine the effect of a degrading bacterium which can effectively reduce the bio-toxicity of oxytetracycline (OTC) metabolites, so as to provide a preliminary theoretical basis for practical application of the strain.  Method  Taking Arthrobacter nicotianae ZAF-05, an efficient OTC-degrading bacterium obtained in the previous studies, as the object, the degradation products of OTC were analyzed by high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (HPLC-Q-TOF-MS). OTC sensitive Escherichia coli, Bacillus subtilis, and Scenedesmus obliquus were used as indicators to evaluate the bio-toxicity of degradation products.  Result  HPLC-Q-TOF-MS analysis showed that the content of highly toxic OTC and its natural hydrolysate epioxytetracycline(EOTC) decreased significantly after treatment with strain ZAF-05, while the content of low toxic isomeric oxytetracyline(ISO-OTC) increased slightly. The growth of tested bacteria and alga in OTC system treated by strain ZAF-05 was significantly better than that in OTC natural hydrolysis treatment and negative control without degrading bacteria, and the difference was significant (P＜0.01). The results indicated that the bio-toxicity of OTC metabolites degraded by strain ZAF-05 was greatly reduced compared with the active drug and its natural hydrolysates. Besides, the degradation effect of the strain alleviated the damage of OTC to the ultrastructure of algal cells, as well as the damage to chloroplasts and cell walls.  Conclusion  Degrading bacterium ZAF-05 can reduce bio-toxicity of OTC residues, which may be related to the conversion of highly toxic substances into non-toxic or low-toxic metabolites in the system. Ch, 7 fig. 1 tab. 26 ref.]