Metatranscriptomics unravel the formation mechanism of key flavors during the natural fermentation of suansun, a Chinese traditional fermented bamboo shoot

Suansun is a naturally fermented vegetable with unique flavor that depends on metabolic activities of microbiota. However, the formation mechanism of the key flavor driven by active microbiota during suansun fermentation is unclear. In this study, metatranscriptomics and metabolomics were used to analyze the key flavor profiles as well as the core functional microorganisms for flavor formation. HS-SPME-GC-MS and UPLC-Q-TOF/MS identified that organic acids, esters, alcohols, aldehydes, phenols and small peptides exert an important influence on the flavor formation of suansun. Based on the metatranscriptomic data, the metabolic network related to the formation of key flavors of suansun was reconstructed. Functional annotation further indicated that 5 genera (including Lactococcus, Enterococcus, Leuconostoc, Lactiplantibacillus and Weissella), which can actively produce enzymes that related to flavor synthesis, were the core functional microorganisms for flavor formation of suansun. These findings contributed to a better understanding of the flavor formation mechanism in suansun and other naturally-fermented foods.