Impact of Microbial Interactions on Growth and Flavor Profiles of Indigenous Yeasts and Lactic Acid Bacteria in Shanxi Aged Vinegar: Combinatorial Co-Cultures Versus Monocultures

Yeasts and lactic acid bacteria, as the predominant microorganisms in Shanxi aged vinegar, play critical roles in shaping its characteristic flavor profile and sensory properties. In this study, we investigated the cooperative fermentation interactions between three yeast strains and two lactic acid bacteria strains isolated from the Shanxi aged vinegar fermentation process. The results showed that Lactiplantibacillus plantarum CPL56 and Pediococcus acidilactici CPL23 promoted the growth of Saccharomyces cerevisiae JLY421 and Candida artemisiae JLY1608, while exerting an inhibitory effect on Saccharomyces cerevisiae JLQ39. Strains JLY421 and JLY1608 also promoted the growth of CPL56 and CPL23, while JLQ39 and CPL23 enhanced the growth of CPL56. Co-cultivation of strains JLY421 and CPL56 at a 1:1 ratio (v/v) resulted in significantly higher total acid and organic acid contents compared to all other combinations. Total organic acid content increased by 200.83% and 81.29% relative to the pure cultures of JLY421 and CPL56, respectively, with lactic acid and acetic acid concentrations reaching 0.3278 g/100 g and 0.0970 g/100 g, respectively. Additionally, the total ester content in this co-culture was also significantly higher than in other combinations, representing a 24.48% increase compared to the JLY421 monoculture. Co-cultivation of JLY421 and CPL56 markedly enhanced both the diversity and content of key volatile organic compounds, including isoamyl acetate, isoamyl alcohol, isobutyl acetate, ethanol, amyl butyrate, p-xylene, acetic acid, 3-hydroxy-2-butanone, and 2,3,5,6-tetramethylpyrazine, relative to their respective monocultures. This study provides foundational insight into yeasts and lactic acid bacteria composite starters in a solid sorghum medium, and may offer a useful reference for future efforts to improve the quality and efficiency of Shanxi aged vinegar production in more complete, multi-stage industrial processes.