Integrated multi-omics analysis of microbial communities and volatile aroma components during cigar tobacco fermentation

This study investigated dynamic changes in key volatile aroma compounds and epiphytic microbial communities during cigar tobacco fermentation. Air-cured “Dexue 1” tobacco leaves were fermented and analyzed using high-throughput sequencing and gas chromatography – mass spectrometry to track microbial community structure and volatile profiles. The contents of total sugar, nicotine, and protein decreased, while the activities of α-amylase, neutral protease, and cellulase increased. While bacterial richness and diversity increased, but fungal diversity decreased. The abundances of Sphingomonas and Massilia initially increased and then decreased, whereas Aspergillus and Alternaria progressively dominated, indicating functional microbial succession. Key metabolic pathways included sesquiterpenoid/triterpenoid biosynthesis, tryptophan metabolism, fatty acid degradation, and isoquinoline alkaloid biosynthesis. The key aroma compounds were phenethyl alcohol, β-ionone, geranyl acetone, copaene, and phenylacetaldehyde. Notably, β-ionone and geranyl acetone correlated positively with Aspergillus , while phenylacetaldehyde and phenethyl alcohol correlated positively with Pseudomonas . The fermentation of cigar tobacco leaves is characterized by the degradation of macromolecules and the accumulation of key volatile compounds, in which microorganisms play a crucial role in metabolic conversion.