Diversity of microbial communities in cigar filler leaves with different initial water contents analyzed based on high-throughput sequencing technology

Yumeng Gao ^1,2 Yang Ning ^2* Yihui Wang ^3* Bingqing Hou ^3* Guo Zhang ^4* Chun Jiang ^4* Song Fang ^2* Qian Wang ²

• ¹ Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
• ² 中国农业科学院烟草研究所, 山东青岛, China
• ³ 山东中烟工业有限责任公司, 山东济南, China
• ⁴ 安徽皖南烟叶有限责任公司, 安徽宣城, China

To study the composition and succession of bacterial and fungal communities during the fermentation of cigar filler leaves with varying initial water contents, high-throughput sequencing technology was used to sequence the bacterial 16SrRNA genes and fungal ITS1 genes from cigar tobacco leaf samples. This was followed by analyses of microbial α-diversity, microbial community structure, and bacterial function prediction based on the sequencing data. Results: The diversity and richness of microbial communities decreased over time during fermentation under different water content conditions. Among the 18 cigar filler leaf samples, the predominant phyla identified were Proteobacteria, Firmicutes, Actinobacteria, Ascomycota, and Basidiomycota, with the leading genera being Staphylococcus, Sphingomonas, Methylobacterium-Methylorubrum, Pseudomonas, and Humicola. Functional predictions for the bacteria revealed their primary involvement in carbohydrate, lipid, and amino acid metabolism. Conclusion: The initial water content of cigar tobacco leaves influenced the structure and relative abundance of microbial communities during fermentation. While the microbial community exhibited a similar structural composition, there were notable differences in relative abundance. The functional prediction results from PICRUSt indicated that the differences in predicted functional species among samples were minimal, whereas the variations in the abundance of functional species were more pronounced across different fermentation stages and initial water contents.