Lactiplantibacillus plantarum and Komagataeibacter europaeus enhance energy metabolism, acetic acid and aromatic amino acids catabolism flux in cider vinegar fermentation

Fruit vinegar is typically produced through a two-stage submerged fermentation involving Saccharomyces cerevisiae (alcohol fermentation) and Acetobacter pasteurianus (acetic acid fermentation). In order to enhance its flavor and nutritional properties, Lactiplantibacillus plantarum and Komagataeibacter europaeus were introduced into the respective stages. The fermentation process was monitored to assess their individual and combined effects, while non-targeted metabolomic analysis aided amino acids and organic acids analysis was applied to characterize the metabolic profiles and identify the differential metabolites. Lactic acid accumulated by L. plantarum, enhanced energy metabolism and ethanol respiratory chain, thereby promoting the K. europaeus growth. In the presence of K. europaeus, A. pasteurianus biomass increased 36–57%, leading to elevated acetic acid synthesis. The co-fermentation systems, especially those containing K. europaeus, exhibited enhanced conversion of shikimic acid to aromatic amino acids and their derivatives such as ferulic acid, isoferulic acid, serotonin, l-kynuanine, phenylacetaldehyde and benzaldehyde. The co-fermentation with K. europaeus and L. plantarum resulted in an enhancement of ethyl phenylacetate, ethyl lactate and ethyl hexanoate production, thereby intensifying the fruity aroma profile. The findings presented here contributed to a deeper comprehension of bioconversion mechanism involving multiple species in cider vinegar fermentation processes.