Fermentation-driven microbial and metabolic shifts in filler tobacco leaves of different grades

Filler tobacco leaves (FTLs) serve as the primary raw material for cigar production, and notable differences in physicochemical properties and fermentation responsiveness exist across different grades. However, the underlying mechanisms governing microbial and metabolic evolution during FTL fermentation remain poorly understood. This study systematically investigated the microbial community structures and metabolomic profiles of FTLs of varying grades before and after fermentation using metagenomic sequencing and untargeted metabolomics.