Metabolism of acetaldehyde and custers effect in the yeast.

Brettanomyces abstinens growing on different initial glucose concentrations showed an anaerobic inhibition of fermentation. This Custers effect decreased as the initial glucose concentration in the medium increased. Two aldehyde dehydrogenases, one NAD+-linked and the other NADP+-linked were observed. The results suggest that the NAD+-linked enzyme is involved in the production of acetic acid and is repressed by glucose. The NADP+-linked enzyme seems to be a constitutive enzyme. Acetyl-CoA synthetase activity also was not greatly affected by the growth conditions. The results support the earlier hypothesis that the Clusters effect in Brettanomyces is provoked by the reduction of NAD+ in the conversion of acetaldehyde to acetic acid.