Isolation And Characterization Of A Nicotine-degrading Strain And Its Application

Nicotine, as the main alkaloid, is up to 95 percent in tobacco. Smoking for a long time will make one addictive to nicotine, and inhaling nicotine excessively will prevent central neurotransmitter from transferring, be paralytic to heart, and even be deathful. Interestingly, microbe and its metabolized enzyme can degrade nicotine, which is helpful for human health, improve the quality of smoke and utility of tobacco leaves and bring a lot of economic benefits.A high nicotine degradation strain Z7 was isolated from soil by selection medium with nicotine as the sole carbon source. The morphological, physiological characteristics and sequence 16s rDNA of the strain showed that it was Agrobacterium radiobacter or Agrobacterium tumefaciens, and the 16s rDNA of the strain and that of Agrobacterium radiobacter or Agrobacterium tumefaciens were 99% homogenous.In optimal medium, the degradation of nicotine was up to 86.2 percent after culturing 24h in rotary shaker(220r/min) at 30℃, initial pH 7.0, 5%inoculum culture. And we found that the enzyme of degrading nicotine of strain Z7 was ectoenzyme,and it was induced enzyme.Strain Z7 has the high ability of degrading nicotine, so we thought about using it to degrade the nicotine in tobacco. With the 10% (v/w) cell at 30℃, 75% relative humidity for 9 days, the decreasing rate of nicotine of tobacco was 40.1%. At the same condition, nicotine content of burley tobacco degreased 35.6%, it also has the high ability of decreasing nicotine. The analysis of chemical ingredient of tobacco demonstrated that the content of protein nitrogen, total sugar was obviously influenced by this strain. To apply this strain to tobacco fermentation, not only the time of tobacco fermentation was cut down greatly, but also the internal quality of tobacoo was improved to a certain degree.