Studies Of Inducing Aroma And Improving Tobacco Quality By Using Fungal Strains

The main purpose of this study is to find fungus strains that are capable of inducing aroma and improving tobacco quality. 4 strains were screened. Biological characteristics and the enzyme mechanism of them were determined.More than 250 isolates were isolated from samples of leafage and soil collected from Yunnan and Shandong provinces. Based on analyzing of chemical, such as soluble sugar, total nitrogen, protein and carotenoid, and referring to the quality standard of tobacco, 7 fungus strains were screened.The results of determination of main chemical contents and the panel test showed that, 4 strains, BF05, BF06, BF07 and BF63 were capable of improving tobacco quality. Aroma quality increased 6.06%, 5.41%, 5.04%, 2.75%, respectively, aroma quantity increased 1.24%, 3.60%, 2.24%, and 1.93% respectively, and offensive and irritancy were reduced. The chemical analysis showed that several main chemical contents of the tobacco leaves treated with fungus strains during growing season and curing period changed remarkably, and showed more harmonious than the control.For the sake of bring the capacity of the fungus strains in improving the aroma quality of tobacco into full play, and to offer proper technical parameter, biological characteristics of 4 strains were determined. As for BF05, the range of temperature of hyphae growth is 25℃-30℃, the optimum is 27.5℃. The range of pH adapted is 6 -11, the optimum pH is 8. PDA is the optimum media. The optimum carbon source is D-fructose and the optimum nitrogen source is potassium nitrate. The natural light (12h/12h) is the optimum light.As for BF06, the range of temperature of hyphae growth is 25℃-30℃, the optimum is 27.5℃. The range of pH adapted is 7-10, and the optimum pH is 8. PDA is the optimum media. The optimum carbon source is maltose and the optimum nitrogen source is potassium nitrate. The optimum light is black light (24h)/purple light (12h)/black light (12h).As for BF07, the range of temperature of hyphae growth is 25℃-35℃, the optimum is 35℃. The range of pH adapted is 5-8, and the optimum pH is 6. PDA is the optimum media. The optimum carbon source is D-fructose and the optimum nitrogen source is vitriol ammonium. The optimum light is natural light (12h/12h) and black light.As for BF63, the range of temperature of hyphae growth is 25℃-30℃, the optimum is 30℃. The range of pH adapted is 5-7, and the optimum pH is 7. LB is the best media. The optimum carbon source is D-fructose and the optimum nitrogen source is potassium nitrate. The optimum light is black light.Changes of enzyme activities (including α-amylase, proteinase, polyphenol oxidase and peroxidase) in treated tobacco leaves were determined. Results showed that the total values of each of enzyme activities was higher than the control, and total values of peroxidase of BF05 and BF06 were higher than the control too, although enzyme activities were different in different time. And changes of chemical substance have closely relativity with enzyme activities.