Isolation Of Nicotine Degradation Microbe And Its Application In The Tobacco Stalks Composting Fermentation

Turning the waste tobacco stalks into biological organic fertilizer is an effective means of reducing environmental pollution and soil-borne diseases propagation caused by tobacco stalks discarded and burned by high temperature composting technology. In this study, a nicotine degrading bacteria was screened, and the medium and culture conditions for it was optimized. It was added to tobacco stalks compost to decrease the nicotine content and promote the compost decomposed. The aim of this study is to play a role for the tobacco stalk compost production and application.In this study, a total of 81 microorganisms which can degrade nicotine were isolated from soil samples, tobacco stalks and laboratory strains. The best strain in degrading nicotine of them, EA-17, was obtained by further screening. According to morphological, physiological and biochemical characteristics and partial sequencing analysis of its 16S rDNA genes, the strain was identified as Arthrobacter histidinolovorans. Through optimization of culture conditions and medium, the suitable medium and culture conditions for growth of EA-17 strain were obtained. That is, K2HPO413.3 g/L, KH2PO4 4 g/L, nicotine 1.5 g/L, glucose 10 g/L, peptone 12 g/L, corn steep powder 8 g/L, (NH4) 2SO412.5 g/L, MgSO40.2 g/L, FeSO40.22 g/L. The fermentation conditions are 30?, pH 6.5 (nature pH). The seed age is 10 h and the inoculation is 2%. Under the medium and culture conditions, nicotine dehydrogenase enzyme activity of EA-17 strain reached 8.11 U/ml, which was 2.92 times of LB medium and much higher than other strains of the genus. EA-17 strain was cultured for 24 h in the fermentation broth with 0.5-4 g/L nicotine in the initial stage. Nicotine degradation rate of the fermentation broth with 0.5 g/L and 1 g/L nicotine was 81.62% and 71.36%, respectively. The rate of the fermentation broth with 2 g/L and 4 g/L nicotine even reached 96.16% and 95.63%.In the hybrid material of tobacco stalks and wastewater (1:1) composting experiment, nicotine degradation rate in treatment added EA-17 strain with mixed inoculants (T) and treatment not added EA-17 strain with mixed inoculants (CK) are 49.33% and 28.27%. The megathermal period of T treatment was 7 days longer compared with CK treatment. The organic matter degradation rate of T treatment attained 33.49% and increased 15.76%. The cellulose and hemicelluloses degradation rate also increased 26.29% and 17.52%,the total N?K content was also improved, which increased 8.05% and 6.62%, respectively.