Screening of a fungus with polysaccharide-degrading enzyme activity and studies of its application in improving the quality of tobacco leaves
[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 and β-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.
Aspergillus aculeatusfungiquality improvement of tobacco leavesbiological enzymes
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