Abstract: Objective: β-Glycosidase plays a crucial role in the hydrolysis of aglycones and subsequent release of grapederived aroma compounds in wine. However, β-glycosidase activity is influenced by many factors. This study was designed taking into account the acid tolerance of Oenococcus oeni to assess and correlate their glucosidase activities with acid stress tolerance. Methods: The cells of O. oeni were implanted with N＋ ion to obtain acid-tolerant (pH 3.0) and acid-sensitive (pH 9.0) mutants. Besides, β-glycosidase activities of all the tested strains were determined. Three groups of variant O. oeni were selected and their β-glycosidase genes were sequenced. Results: The acid-tolerant mutants harbored a significantly increased β-glucosidase activity that was 2–4 times higher than that of the original strains, and 2–7 times higher than that of the corresponding acid-sensitive mutants. Sequencing results of eight representative amplicons indicated that all the mutants and their parental strains were identical to each other, except a3 mutant, which formed two base transversions at 108 gene locus (G→C) and at 1 232 locus (A→T). Conclusion: Correlation analysis indicated that O. oeni β-glycosidase activity was significantly positively related to acid stress resistance (P < 0.05).

Key words: Oenococcus oeni, ion implantation, acid tolerance, β-glucosidase, correlation analysis