Oxidative fermentation of glucose and ethanol in designed media and cooked grape must by acetic acid bacteria

In this study, acetic acid bacteria strains were investigated for their ability to oxidize different carbon sources producing the corresponding oxidative products. Bacterial strains were cultivated in seven designed media and their acetification ability was assessed. The most performing strains were further tested to evaluate gluconic acid production in cooked grape must. Organic acids, sugars, and ethanol concentrations were assayed by high-pressure liquid chromatography. Overall, the findings showed high variability amongst strains of the same species, especially amongst Gluconobacter oxydans strains. However, strains ATCC 621H and DSM 3503T resulted to be the highest gluconic acid producers in all tested conditions. This study shows that grape must can be further valorized by selective fermentations for the production of gluconic based products.