Interaction Between Lactic Acid Bacteria And Acetic Acid Bacteria In The Acetic Acid Fermentation Process Of Shanxi Aged Vinegar

Shanxi aged vinegar(SAV)is produced with a typical solid-state fermentation(SSF)process in which various microorganisms are spontaneously enriched and disappeared.Lactic acid bacteria(LAB)and acetic acid bacteria(AAB)are most crucial to the quality of SAV,their interactions in the SSF process would bring changes of microbial communities structures and metabolisms,which determine the quality and safety of SAV.In this study,the succession of LAB and AAB and their potential driven factors in solid-state acetic acid fermentation(AAF)process were revealed by using high-throughput sequencing and canonical correlation analysis(CCA)methods.Interactions between LAB and AAB were investigated by using culture-dependent method in situ simulation,and transcriptome were explored to reveal the interaction mechanisms.The results will greatly increase the scientific understanding of the brewing mechanism in the SSF process and may render rational strategies for regulating the fermentation process.Results of high-throughput sequencing indicated that the relative abundance of LAB was decreased and AAB was increased gradually in AAF process.5 species of Lactobacillus account for 98%relative abundance of LAB were detected,among them,species of Lactobacillus helveticus which account for 55%relative abundance of Lactobacillus was the predominant LAB.12 species of Acetobacter account for 95%relative abundance of AAB were detected,among them,species of Acetobacter pasteurianus which account for 70%relative abundance of Acetobacter was the predominant AAB.CCA indicated that acetic acid,ethanol,lactic acid,and temperature serve as the most potential driven factors for the succession of Lactobacillus and Acetobacter.The growth and metabolism of L.helveticus CGMCC 1.1877 and A.pasteurianus CP-All in mono-and coculture SSF media were measured.Results indicated that the interaction relationship between L.helveticus CGMCC 1.1877 and A.pasteurianus CP-All was amensalism in AAF process.The coculture system was harmful to the growth and metabolism of L.helveticus CGMCC 1.1877,and in favor of the metabolism of A.pasteurianus CP-All.The effects of fermentation conditions and environmental tolerance of Lactobacillus on microbial interactions were analyzed.It showed that the accumulation of acetic acid and lactic acid,ethanol(converted to acetic acid)and high temperature would inhibit the microbial growth and metablisms.And the inhibition effects on L.helveticus CGMCC 1.1877 were stronger than that of A.pasteurianus CP-All,but Lactobacillus with excellent environmental tolerance promoted the growth and metabolism of A.pasteurianus CP-A 11.The interaction mechanisms between L.helveticus CGMCC 1.1877 and A.pasteurianus CP-All in AAF process were studied by combining metabolites with transcriptome methods and results showed that L.helveticus CGMCC 1.1877 were manily inhibited by acetic acid which was oxidized from ethanol by A.pasteurianus CP-All.Also,metabolites of L.helveticus CGMCC 1.1877 promoted glucose pathway and further promoted the pathway of sulfer metabolism which related to the celluar respiration and energy metabolism of A.pasteurianus CP-All.Therefore,the oxidation of ethanol;transfer of acetic acid;and transfer of quorum sensing molecular of A.pasteuriarnus CP-All were promoted.