Microbial n-propanol synthesis during Luzhou-flavor liquor fermentation

Abstract:

[Objective] To reveal the metabolic pathways of n-propanol synthesis and corresponding microorganisms during Luzhou-flavor liquor fermentation.[Methods] The microorganisms and metabolic pathways related to the synthesis of n-propanol were analyzed by metatranscriptome analysis, and the capability of corresponding microorganisms to synthesize n-propanol was investigated.[Results] Three possible n-propanol synthetic pathways were discovered during Luzhou-flavor liquor fermentation. All of them contributed to the synthesis of n-propanol based on the transcriptome analysis. However, the time and capability of microorganisms to synthesize n-propanol through these pathways were different. Fungi synthesized n-propanol mainly through citramalate pathway and threonine metabolic pathway, whereas bacteria synthesized n-propanol through propanoate pathway and partial threonine metabolic pathway. Moreover, yeast strains and lactic acid bacteria isolated from fermented grains were confirmed to be corresponding to the synthesis of n-propanol during Luzhou-flavor liquor fermentation.[Conclusion] Discovery of metabolic pathways of n-propanol synthesis and corresponding microorganisms during Luzhou-flavor liquor fermentation help to understand the formation mechanism of n-propanol in the process of Chinese liquor fermentation.