Identification And Application Study Of Bacterial Communities On Flue-cured Tobacco Leaves

Microorganism plays an important role on tobacco processing, especially on the fermentation.However, most of the studies of microorganism on tobacco fermentation are staying inculture-dependent phase. In order to make fully understanding of the bacterial communitieson aged flue-cured tobacco leaves, next generation sequence technology (NGS) was used toidentify the whole bacterial communities of flue-cured tobacco leaves and the culturedsamples from different produce areas through16S rRNA analysis. Meanwhile, theculture-dependent method has been used here to dig out the enzyme production strains withapplication potential on improving the quality of low grade aged tobacco leaves. The resultsof this study are as following:1. Two aged flue-cured tobacco leaves samples from Kunming, Yunnan and Xiangxian,Henan with grade C3F and their cultured samples were selected for16S rRNA analysisby high throughput sequencing. The results showed that the both bacterial communitiesof Kunming and Xiangxian are with similar structures, especially on the domain bacterialphylum.The Poteobacteria is the most abundant bacterial phylum with the percentage of89.76%and91.87%in Kunming and Xiangxian, respectively. And Firmucutes is with thepercentage of6.61%and4.27%in Kunming and Xiangxian, respectively, as the secondabundant bacterial phylum. However, the number of operational taxonomic unit ofKunming and Xiangxian, which are281and174, suggested that Kunming sample waswith higher diversity. Meanwhile, we found that the diversities of both cultured bacterialcommunities from Kunming and Xiangxian were decreasing during the cultureprocessing in which Bacillus has become the only domain bacteria with overwhelmingpreponderance. This study has provided the evidence for that the difference of agedflue-cured tobacco leaves from different areas may course by their bacterial communities.Besides, the results also have made contribution to the research of tobacco artificialfermentation as the cultured processing was considered to be a model of artificialfermentation.2. With the traditional culture-dependent method, we have separated73bacteria strainsfrom flue-cured tobacco leaves of5produce areas and52enzyme production strains werescreened according to their abilities on producing protease, amylase, cellulose, xylanaseand pectinase. The results showed that most of the enzyme production strains are about toproduce protease, amylase, cellulose. On the contrary, fewer strains producexylanaseand/or pectinase. We found that the grade B2F tobacco leaves got higher score in smoke penal test after being processed by the bacterial communities or the enzymeproduction strains we have screened.4bacterial communities and3strains were withoutstanding performance on improving the aroma and quality of low-grade tobaccoleaves. Those aroma-increasing strains and bacterial communities are with greatindustrial potential on tobacco fermentation.