Objective: The purpose of this work was to screen strains having tobacco-specific nitrosamines (TSNA) deteriorating activity, isolated from the inner and superficial of tobacco plants. Then strain AS97 was isolated and identified for further application.
Methods: Strain AS97, with the highest conversion ability against both nitrate and nitrite, was screened by enrichment and selective medium. The strain was identified by morphological, physio-biochemical characteristics and 16S rRNA gene sequence analysis. The concentration of 4-(methylnitrosamino)-1-(3-pyridy)-1-butanone (NNK), N-nitrosonicotine (NNN), N-nitrosoanatabine (NAT) and N-nitrosoanabasine (NAB) were determined by LC-MS/MS. The fermentation broth of strain AS97 was spraied on the leaves of tobacco to define inoculum concentration and fermentation condition.
Results: AS97 was identified as Pseudomonas fluorescens (Genbank accession number: JF 449445). Under the optimal growth conditions with inoculum concentration of 5%, at 30 degrees C for 10 d, AS97 had high biological activity against NNK and NNN with a degradation rate of 59.08% and 38.79%, respectively. The correlation analysis displayed a pronounced correlation (p > 0.01) among the concentration of nitrate, nitrite and TSNA. Furthermore, the results also exhibited that nitrate and nitrite were antecedent substance of TSNA.
Conclusion: These results indicated that Pseudomonas fluorescens AS97 could be a promising microorganism in the practice of non-harmful cigarette production.