一株降烟碱细菌的筛选、鉴定及其降解特性研究

以烟碱为唯一碳源，从湖南张家界烟草种植地的土壤中分离得到一株降解烟碱能力较好的菌株。经常规形态观察和生理生化实验结果表明，该菌为放射形土壤杆菌或根癌土壤杆菌(Agrobacterium radiobacter／tumefaciens)。研究表明，该菌的降解烟碱最适pH和温度分别为7.0和30℃。该菌能够利用烟碱为唯一碳源，在含烟碱的培养基中发酵液呈淡黄色-绿色-墨绿色-深综色变化，培养48h后，烟碱的降解率可达71%，具有较好的烟草工业应用前景。

Isolation and characterization of a strain Z7,capble of degrading nicotine

A nicotine-degrading bacterial strain Z7 was isolated from tobacco growing soil at Zhangjiajie region in Hunan Province. The morphology, physiological and biochemical characteristics of strain Z7 were studied and the results showed that characteristics of this strain were essentially consistent with Agrobacterium radiobacter/tumefaciens. This strain degraded nicotine optimally at 30℃　and initial pH 7. It was able to utilize nicotine as its sole carbon source, and it could degrade 71% of nicotine under the optimized incubation conditions for 48 h. Meanwhile，the color of culture medium turned from yellowy to green and dark green, then it turned to brown. This strain might have potential applications in tobacco industry.