Microbial community structure of cigar tobacco leaves in Hunan production area and its regulatory mechanism on quality formation

Introduction To elucidate the microbial community structure of domestic cigar tobacco leaves and its regulatory function in quality formation, the present work focuses on characterizing microbial flora, identifying origin-mediated community divergence, and exploring their linkages to flavor quality for cigar tobacco planted in Hunan. Methods High-throughput sequencing, chemical profiling and sensory evaluation were combined to systematically analyze different cigar varieties from the Hunan production region. ANOSIM and correlation network analysis were performed to evaluate microbial community variation and inter-taxa correlations. Results and discussion Bacterial communities were dominated by Proteobacteria , Cyanobacteria , Firmicutes , and Actinobacteria ; fungi were overwhelmingly dominated by Ascomycota (relative abundance >93%). At genus level, dominant bacteria included Pantoea , Pseudomonas , Klebsiella , Brachybacterium , and Curtobacterium , while dominant fungi were Aspergillus , Gibberella , and Alternaria . ANOSIM (R = 0.50, P = 0.001) demonstrated that geographical origin acted as the primary driver of microbial community differentiation, and the same cultivar Cuba No.7 showed highly significant interregional differences (R = 0.95, P = 0.001). Correlation network showed flavor-positive genera ( Pantoea , Curtobacterium , Aureimonas ) were enriched in Yongding District samples, whereas flavor-negative genus Trichoderma was abundant in Sangzhi County and Chenzhou samples. Unsaturated fatty acids, succinic acid and malic acid were key metabolites connecting microbial communities and sensory traits. These results support the hypothesis that microorganisms dominate quality formation of cigar tobacco leaves, and offer theoretical support for site-specific cultivation and fermentation optimization based on regional microecological features.