Abstract:To reveal the relationship between the dominant microbial communities on tobacco leaf surface and the quality of tobacco, the structure of microbial community in tobacco with different qualities was analyzed by high-throughput sequencing technique, and the volatile aroma compounds were detected by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC/MS), and the dominant microbial species related to the formation of volatile aroma components in tobacco were analyzed by calculating Pearson correlation coefficient. The results showed that the dominant bacteria in tobacco were Variovorax, Spingomonas, and Bacillus, while the dominant fungi were Sampaiozyma, Aspergillus, and Cladosporium. The bacterial communities were related to the difference of tobacco leaf qualities, and the relative abundance of Variovorax, Spingomonas, and Rhodococcus was up-regulated in the high-grade and middle-grade tobacco leaves. However, the fungal communities were related to the geographic location differences of tobacco leaves. The contents of volatile compounds were higher in high-grade and middle-grade tobacco, such as furfural and 5-methyl-2-furancarboxaldehyde of caramel aroma, and sweet milk-flavored vanillin. There was more α-nicotine producing irritating smoke in the low-grade tobacco. Combined with the correlation analysis, a positive correlation was found between bacterial species and various volatile aroma compounds in tobacco leaves, and Rhodococcus, Variovorax and Bacillus were the main flavor-associated bacteria in tobacco. The results showed that the dominant microbiota in tobacco played a critical role in promoting the formation of tobacco aromatic quality, which could provide a theoretical reference for the realization of tobacco quality improvement and damage reduction, as well as the targeted regulation of flavor based on the microbial technology.
