| Nicotine was a main alkaloid and toxic compound in breeds of tobacco, which was one of environment contaminations. Some microorganisms were able to utilize nicotine in different pathway,some of which could be applied in the tobacco waste treatment. Thus, studies about nicotine-biodegradation are very popular these years.A novel nicotine-degrading bacterium was isolated from tobacco leaves. Based on the results of standard morphological identification, physiological and biochemical characters and 16S rDNA sequence analysis, it was identified and named as Pseudomonas stutzeri ZCJ. The tolerance of nicotine for strain ZCJ is 4.5 g·L-1 and the optimal conditions for nicotine degradation are at 37℃with initial pH 7.5. While culturing, the color of the medium turns from colorless to light green, dark green, black and finally brown. The additional glucose (1 g·L-1) could improve the nicotine degradation by Pseudomonas stutzeri ZCJ. Until now, there is no manuscript reporting that Pseudomonas stutzeri could utilize nicotine. By using the cell suspention of Pseudomonas stutzeri ZCJ to treat tobacco stocks, it is found that when the reaction surface area was bigger enough, the tobacco leaves with cell suspention was 2: 1, the degradation ratio of nicotine in 1 g tobacco leaves could be more than 15 % per week.Yeast extract and phosphate additions improved nicotine degradation in 5 % TWE by Pseudomonas sp. ZUTSKD while additional K and Na showed no difference. With additional 1.0 g·L-1 yeast extract and 2.667 g·L-1 phosphrous (calculated) in 5 % TWE, Pseudomonas sp. ZUTSKD could degrade 96.2 % and 97 % of nicotine in 12 h, respectively. The double-factor orthogonal experiment demonstrated that phosphate had the strongest effect on nicotine degradation while the reciprocal effect between yeast extract and phosphate had a lesser effect. The data showed that strain ZUTSKD could be useful to control the nicotine content in TWE. |
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