摘要
Ester production in medium-high temperature Daqu(MHT-Daqu)significantly influences the flavor profile of strong-flavor Baijiu,but the details remain unclear.This study aimed to comprehensively profile the global map of ester-producing metabolism and the involved key genes using multi-omics approaches.Metatranscriptome and metaproteome found that the global map of ester-producing metabolism mainly included carbohydrates,amino acids,organic acids.Integrated targeted metabolomics showed that the synthesis metabolism of alginate,glucose and arabinitol dominated by EC 2.4.1.64 and EC 3.2.1.86 was the main carbohydrate metabolism pathway,which was a prerequisite for ester production.The synthesis metabolism of glutamine,lysine,leucine,and glutamate dominated by EC 2.6.1.16,EC 3.4.19.13,and EC 1.5.1.7 was the main amino acid metabolism pathway,but its effect on ester production was not significant.The pyruvate metabolism transformation pathway,dominated by EC 2.2.1.6(acetolactate synthase,ALS)and EC 6.4.1.1,was one of the major organic acid metabolic pathways,which promoted ester production.Gene cloning and expression analyses found that,the expression patterns of the three genes cloned from the MHT-Daqu cDNA library in situ,JqALS1 encoding ALS,JqAAT1 encoding alcohol acetyltransferase,and JqADH1 encoding alcohol dehydrogenase,were overall consistent with the ester profiles over the whole production,proving their key role.Among them,the expression of JqAAT1 was significantly positively correlated with the environmental starch,amino acid nitrogen,and reducing sugar,while the expression of JqALS1 was mainly stimulated by the environmental temperature.These results facilitate the understanding of ester production in MHT-Daqu and the improvement of Baijiu flavor.
基金
supported by National Key R&D Program of China(No.2018YFE0127400)
Open-foundation project Liquor Making Biological Technology and Application of Key Laboratory of Sichuan Province(No.NJ2023-01★).
