Metabolic Characteristics of Amino Acid in Mixed Fermentation of Bacillus and Yeast Using Wheat Flour as Substrate

In order to elucidate the metabolic characteristics of the liquid mixed fermentation of liquor-making microorganisms,the common bacteria(Bacillus licheniformis)and yeasts(Hansenula,Pichia fabianii,Saccharomyces cerevisiae and Zygosaccharomyces rouxii)in traditional solid-state fermentation of baijiu were used as the research objects,and the metabolic characteristics of amino acid were analyzed under the mixed fermentation of Bacillus and single yeast when wheat flour was used as the sole substrate in this research. The results showed that Hansenula was the main ethanol-producing yeast under mixed fermentation and the highest ethanol concentration was(93.33±4.71) mg/L. The corresponding reducing sugar level was the lowest,not exceeding 1 g/L. Gas chromatography analysis showed that 11 amino acids including glycine,valine,isoleucine,threonine,proline,glutamic acid & glutamine,phenylalanine,histidine and tyrosine were synthesized under four mixed fermentation conditions. For amino acids that occurred only in specific microbial combinations,Hansenula was more likely to accumulate serine,methionine,cysteine and lysine than Pichia. Alanine was specific amino acid in mixed fermentation of B. licheniformis and Pichia. The results of this study revealed the metabolic characteristics of amino acids under the mixed fermentation of liquor-making microorganisms,and provided a theoretical basis for further study of the relationship between amino acids and flavor.