Acetate-ester hydrolase activity for screening of the variation in acetate ester yield of Cyberlindnera fabianii, Pichia kudriavzevii and Saccharomyces cerevisiae

Esters constitute an important class of aroma compounds and contribute significantly to the aroma of yeast-fermented beverages. Ester formation is well studied in Saccharomyces cerevisiae, while production of aroma compounds by non-conventional yeasts has received little attention. The selection of such strains for co-culturing with S. cerevisiae offers opportunities for product innovations. Therefore, we performed a comparative analysis of the diversity in ester production by Cyberlindnera fabianii 65 (Cf65), Pichia kudriavzevii 129 (Pk129) and S. cerevisiae 131 (Sc131). For all three species distinct aroma profiles were identified, with Cf65 producing the highest amount of acetate esters. Since esters are formed from alcohols and acyl-CoA or acetyl-CoA, we analysed in vitro alcohol dehydrogenase and alcohol acetyl transferase activities in those three yeasts and found no correlation with ester formation. In contrast, a clear inverse correlation between the acetate-ester hydrolase activity and acetate ester yield was found for the three yeast species. Our study indicates that acetate-ester hydrolase activity plays a key role in determination of the final amount of acetate esters in fermentation broths.