Interaction between microorganisms and flavour products during cigar fermentation promoted by citrus Reticulata-“Chenpi” derived Enterobacter G5Z-2: based on multi-omics studies and microbial profiles

Introduction Cigar fermentation is crucial for developing its characteristic aroma, exogenous microorganisms can be used to enhance fermentation. It is reported that the citrus reticulata ‘Chachi’ (Chenpi, a traditional fermented ingredient) extract can improve the flavor of cigarette. However, there is no report on the influence of Chenpi-derived microorganisms on the fermentation process and flavor quality of cigar tobacco leaves (CTLs) till now. Methods A fermentation strain ( Enterobacter hoffmannii , G5Z-2) was isolated from Chenpi, and it was applied as a bioaugmentation agent in CTLs fermentation. A multi-omics approach, including metagenomics and metabolomics, was employed to investigate its impact. Results Inoculation with G5Z-2 significantly altered the microbial community structure, suppressing native Pseudomonas and reducing overall alpha diversity while enriching beneficial genera like Aspergillus and Staphylococcus . Metabolomic analysis revealed substantial restructuring of metabolic pathways, particularly the enrichment of amino acid metabolism (such as arginine biosynthesis and phenylalanine metabolism) and nicotinate/nicotinamide metabolism. This led to accelerated degradation of proteins and amino acids, providing precursors for Maillard reaction, and a marked increase (57.5%) in total volatile flavour compounds, including key aroma constituents from carotenoid and cembranoid degradation. Conclusion The Chenpi-derived E. hoffmannii G5Z-2 optimises the fermentation process by modulating the microbial consortium and driving metabolic shifts towards favourable flavour development, demonstrating significant potential for improving the quality of Chinese-style cigars.