| In this study, cellar mud from a winery in southern Sichuan was used as the research object. In the experiments of isolation and screening of caproacidobacteria in an anaerobic workstation, 120 experimental strains were finally obtained.These strains were screened using bacterial morphology analysis, Gram staining, spore staining, physiological and biochemical tests, gas chromatography-mass spectrometry (GC-MS), and agarose gel electrophoresis of PCR products. Following enrichment and streaking screening, eight target bacteria were selected and designated as SY1 to SY8. Further analysis identified SY4 as Clostridium kluyverii, SY1–SY3 as Bacillus Belesenii, and SY5–SY8 as Bacillus siamicus. Subsequent cultivation revealed that the fermentation products of these 8 strains contained caproic acid, a key organic acid component that significantly influences the flavor of liquor. The results demonstrated that these eight strains were core producers of organic acids in the aromatic substance skeleton of strong-flavor liquor. Optimal fermentation conditions for SY4 were determined to be 34°C, initial pH 6.0, ethanol concentration 2%, fermentation time 14 days, inoculation ratio 5%, with a caproic acid yield reaching up to 10.1 g/L. In co-culture fermentation experiments, the co-culture of Aspergillus fuchsinensis produced higher levels of volatile compounds compared to pure caproic acid-producing bacterial fermentation broth, including 10 alcohols, 21 esters, 9 acids and 3 aldehydes. Conclusion These findings not only provide a scientific basis for the screening of high-yield caproic acid-producing strains and the application of co-culture fermentation to enhance the flavor of strong-flavor liquor but also offer new insights into the research and development of volatile flavor compounds in liquor. |
