Screening and Identification of Non-Saccharomyces Yeast Strains with High Glycosidase Production and Changes in Enzyme Activities during Their Fermentation

This study was conducted in order to explore the fermentation capacity and glycosidase activity of indigenous non-Saccharomyces isolated from naturally fermented grape juice from the eastern foothill of Helan Mountain using WL medium and esculin medium. The activity of β-D-glucosinase, β-D-xylosidase, α-L-rhamnosidase, and α-L-arabinosidase of the isolates were determined and compared using the p-nitrophenol method. The growth kinetics and glycosidase activity of six selected strains were monitored during the fermentation of synthetic grape must by each of them. The results showed that the six non-Saccharomyces strains with high glycosidase activity were identified as Hanseniaspora opuntiae, Metschnikowia pulcherrima, Hanseniaspora uvarum, and Torulaspora delbrueckii through sequence analysis of the D1/D2 domain of 26S rDNA, but their glycosidase activities were different. T. delbrueckii showed better fermentation capacity for synthetic grape must and higher cumulative glycosidase activity (94.10–127.70 mU/mL) than the other strains, which was 1.96–2.30 folds higher than the control strain. M. pulcherrima had high α-L-rhamnosidase and α-L-arabinosidase activity, while H. opuntiae and H. uvarum-3 showed high β-D-xylosidase and α-L-arabinosidase activity. In conclusion, these strains of non-Saccharomyces yeast have high glycosidase activity and possess good application potential for wine aroma enhancement.