Co-culture of Acetobacter pasteurianus and Lactobacillus plantarum enhances biofilm formation and improves vinegar characteristics

Acetic acid bacteria and lactic acid bacteria are core microbial components in traditional Chinese vinegar brewing, where biofilm-associated microflora form unique and stress-resilient consortia. This study explored bacterial adaptive responses and biofilm development in bicultures of Acetobacter pasteurianus with individual Lactobacillus strains. Across all bi-cultures, A. pasteurianus exhibited a competitive dominance over Lactobacillus strains. Notably, co-cultivation of A. pasteurianus with L. plantarum markedly promoted biofilm formation, independent of autoinducer-2 signaling. Transcriptomic and metabolomic analyses revealed that both strains employed effective acid-resistance strategies. However, A. pasteurianus prioritized energy generation and intracellular redox balance, whereas L. plantarum enhanced biosynthesis of cellular building blocks. Complementary pathways, including those involved in lactic acid, sorbose/sorbitol, and galactose/galactitol metabolism, facilitated interspecific mutual adaptation. These regulations, together with increased production/export of lipopolysaccharides, lipoproteins, organic acids, amino acids and nucleotides, as well as the activated quorum sensing and biofilm pathways in A. pasteurianus, collectively reinforced the co-cultured biofilm development. Further, A. pasteurianus-L. plantarum co-fermentation significantly improved acid production and antioxidant activity of vinegar. This study provides insights into the regulatory mechanisms for the dominance of A. pasteurianus over L. plantarum and the enhanced biofilm formation in their co-culture, offering implications for optimizing their application in vinegar fermentations.