一株具有多糖降解酶活性的真菌菌株的筛选及其在烟叶品质提升中的应用研究

Screening of a fungus with polysaccharide-degrading enzyme activity and studies of its application in improving the quality of tobacco leaves

【目的】获得对烟叶品质有提升效果的微生物菌种。【方法】以醇化两年的烟叶为材料,筛选出具有较强多糖降解酶分泌能力的真菌,进行种属鉴定、发酵条件优化和应用效果研究。【结果】(1)从烟叶中分离到5株丝状真菌,通过生物酶活性比较分析筛选到一株具有较强多糖降解酶活性的菌株S1。经形态学和分子生物学分析,该菌种鉴定为棘孢曲霉。(2)对菌株S1发酵条件进行优化,发现其在pH 6、30℃、10%接种量条件下发酵6 d时产酶量最高,其中纤维素酶、淀粉酶、阿拉伯呋喃糖苷酶、果胶酶、木聚糖酶、β-葡萄糖苷酶活力分别达到0.36 U/mL、8.48 U/mL、0.25 U/mL、3.71 U/mL、17.98 U/mL和3.19 U/mL。(3)施用菌株S1发酵液的烟叶样品的可溶性糖含量和多种有机酸、酮类、醛类、芳香类、醇类致香物质含量显著提高,烟碱和多种多糖大分子含量显著降低。【结论】本研究分离得到一株具有多糖降解酶活性的棘孢曲霉,在提升烟叶品质的应用方面具有较大的开发潜力。

[Background]To screen microbial strains that are effective in improving the quality of tobacco leaves.[Methods]A fungal strainwith strong capacity to secret polysaccharide-degrading enzymes was screened fromtobacco leaves that had been aged for two years,and subjected for species identification,fermentation condition optimization,and application in the treatment of tobacco leaves.[Results](1)Five fungi were isolated from tobacco leaves,and through the comparative analysis of their enzyme activities,one strain S1 with high polysaccharide degrading enzyme activities was screened.Morphological and molecular biological analyses showedthat the strainis Aspergillus aculeatus.(2)The fermentation condition of strain S1 was optimized,and it was found that the highest enzyme production was achieved at pH 6,30℃,and inoculum of 10%.Under this condition,the activities of cellulase,amylase,arabiofuranosidase,pectinase,xylanase andβ-glucosidase reached 0.36 U/mL,8.48 U/mL,0.25 U/mL,3.71 U/mL,17.98 U/mL and 3.19 U/mL,respectively.(3)Tobacco samples treated with the fermentation broth of S1 had significantly increased contents of soluble sugars as well as aroma constituents such as various acids,ketones,aldehydes,aromatics,and alcohols,while the contents of nicotine and polysaccharide significantly decreased.[Conclusion]In conclusion,a A.aculeatus strainwith polysaccharide-degrading enzyme activities was isolated,and it has great development potential in improving the quality of tobacco leaves.