Integrated analysis of proteome and metabolome reveals the basis of amino acid metabolism in cigar artificial fermentation

Cigars are a type of tobacco product made entirely from dried tobacco, primarily consisting of the filler, binder, and wrapper. Fermentation is a key step in improving the quality of cigar tobacco leaves (CTLs). To investigate how fermentation affects quality, this study employed non-targeted metabolomics and data-independent acquisition (DIA) proteomics to examine the metabolic changes and protein expression levels in tobacco leaves. The results reveal that a total of 112 differential metabolites were identified through untargeted metabolomics, with 87 compounds demonstrating a decrease in relative abundance post-fermentation, including 20 amino acids and their derivatives. Utilizing DIA proteomics, 341 differentially expressed proteins were identified. Functional analysis of these proteins revealed variations in biological functions at different fermentation stages. A total of 21 driver proteins exhibited significant correlations with the metabolic regulation of eight amino acids. This study revealed the transformation of amino acid metabolism significantly affects the quality of CTLs. It enhanced the understanding of amino acids among the differential metabolites before and after fermentation. This research provides a theoretical basis for the control of amino acids during the artificial fermentation process of CTLs, aiming to further improve their quality.