The impact of Staphylococcus saprophyticus on the fermentation of cigar filler tobacco leaves and the dynamics of microbial community.

Introduction: Staphylococcus has garnered increasing attention for its role in improving fermentation results and promoting the biosynthesis of aromatic compounds. Methods: This study investigated the effects of exogenously introduced Staphylococcus saprophyticus on the microbial community structure, functional gene expression, and volatile aroma profiles during the fermentation of cigar filler leaves. Results: The results demonstrated that S. saprophyticus significantly enhanced the accumulation of alcohols and ketones. LEfSe analysis identified Bacillus as a key differential genus in the inoculated group. Spearman correlation analysis revealed positive associations between Staphylococcus and Bacillus, as well as with key aroma compounds such as 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo [4.1.0] heptane and cis-6-nonenal. EGGNOG functional annotation indicated upregulation of carbohydrate and amino acid metabolism pathways. Additionally, CAZy analysis revealed increased abundance of glycosyltransferases and carbohydrate-binding modules, which may facilitate sugar conversion and utilization. Discussion: These findings provide a theoretical basis for the application of exogenous microorganisms in cigar fermentation and offer insights into the regulation of microbial community structure for quality improvement.