Isolation And Identification Of A Strain With Ability To Degrade Starch And Protein Simultaneously From Tobacco Leaf And Its Effect On Composition Of Tobacco Leaf

As tobacco leaf fermentation process is extremely an important part of cigarette processing, microbial fermentation technology induced transformation of organic matter in the tobacco, promote the accumulation of tobacco flavor, and taste of tobacco can be improved to reduce “green” taste and improve the quality of tobacco smoking.In this study, a strain isolated from leaf surface can be screened simultaneously degrading starch and protein in tobacco, which named XP01, spraying the strains acting on the leaf surface, at 37 ℃, 80%RH condition for solid state fermentation, and then measured chemical components as well as aroma components changes before and after fermentation. The strain was observed by morphology and 16 S rDNA sequencing, and the strain producing amylase and protease activity were measured. The results of this study were as follows:1. The strain was sequenced as Bacillus subtilis(Bacillus subtilis subsp)(99%homology).2. With the grownwith time of the strain, the production of amylase and protease activity were both from increased to decreased, amylase activity was up to 190.06 ± 3.58 U/mL, and protease activity was up to 14.29 ± 0.06 U/mL.3. The changes in leaf carbohydrate is mainly reflected in the starch contentdecreased significantly after fermentation, reaching 33.87%; water-soluble sugars except glucose decreased by 6.28%, fructose and sucrose were increased in different degrees. Content of total nitrogen and total volatile base nitrogen compounds content increased in different degrees, protein and total alkaloids were decreased, which decreased 20.00% of protein; amino acids except leucine and tyrosine content decreased slightly, the other amino acid content increased in varying degrees, of which the highest proline content in a variety of amino acids, cystine, lysine and glycine are the most significant growth. Ash content decreased slightly, potassium and chloride ions content decreased by 3.45% and 3.36%. Reflect the total aroma petroleum ether extract content increased by 0.84%. As the organic acid content of one of the main sources of aroma changed significantly, oxalic acid and malic acid content decreased by 2.82% and 7.40%; lactic acid, citric acid, succinic acid, respectively, an increase of 2.50%, 5.89% and 15.29%.4. After simultaneous distillation extraction and GC-MS analysis was fermented aroma composition before and after the fermentation in tobacco. The total amount of aroma components from 611.98 μg/g increased to 657.05 μg/g, an increase of 7.36%. Where the alcohol content of the largest, accounting for over 50% of the aroma of the total, grew 22.17% after fermentation; content of carbonyl compounds followed, accounting for more than 25% of the total aroma, a slight decrease after fermentation, 3.66% lower. Degradation of plastid pigments, phenylalanine degradation, browning reaction, cembranoids degradation and other major reactions, besides there are some main characteristic aroma components, such as dihydroactinidiolide, β-damascone, megastigmatrienone, solanone.In this study, screening of a microbial strain from leaf surface biodegradable starch and protein in tobacco leaves at the same time, and to explore the effects of the strain on the physical and chemical composition also aroma components of tobacco. After fermentation by microbial strain XP01, tobacco smoking affects the quality of the content of macromolecules as starch and protein decreased, a corresponding increase in sugar hydrolyzate small molecules, such as amino acids. Increased the quantity of flavor, and improved the aroma quality.