Metatranscriptomics reveals microbial community function succession and characteristic flavor formation mechanisms during black rice wine fermentation

Black rice wine (BRW) is a traditional Chinese rice wine with unique flavors; however, the formation pathways of flavor compounds driven by microbiota remain unclear. This study employed HPLC and GC-MS to reveal that during BRW fermentation, free amino acids increased sevenfold, volatile compounds doubled, and 28 key characteristic flavor compounds were identified. Metatranscriptomic analysis indicated that during fermentation, driven by physicochemical factors and microbial interactions, Saccharomyces gradually became the dominant active microorganism (relative abundance 87.01%-97.70%). Other dominant microorganisms (relative abundance >0.1%), including Saccharomycopsis, Pediococcus, Wickerhamomyces, and Weissella, significantly decreased. Meanwhile, the microflora's signature functions underwent succession: transcription early, carbohydrate metabolism mid-stage, and autophagy late. These microbial and functional successions facilitated the accumulation of flavor compounds. Metabolic network reconstruction revealed that Saccharomyces was pivotal in substrate degradation and flavor formation, while other dominant microorganisms actively promoted these processes. This study provides insights into regulating BRW's flavor through microorganisms.