Microbial community structure and function of Yunnan cigar tobacco leaves based on high-throughput sequencing

【Objective】 To explore the microbial community structure and diversity of cigar tobacco leaves after agricultural fermentation in different producing areas and uses in Yunnan，which could provide reference for screening functional microorganisms of cigar tobacco leaves and improving the fermentation quality of cigar tobacco leaves. 【Method】 The microbial community structure was analyzed based on high-throughput sequencing technology，and the metabolic functions of the microbial community were analyzed and predicted using cigar tobacco leaves with different uses（cigar wrapper，filler and binder leaves）from 3 origins，namely Dehong，Lincang and Pu’er in Yunnan，as the test materials. 【Result】 Operation taxonomic unit（OTU）cluster analysis was performed according to 97% similarity，and a total of 2393 OTUs were obtained. The number of OTUs in each sample ranged from 125 to 442，and there was a large difference between samples. The Chao1 index，ACE index and Shannon index of tobacco leaf samples of different uses from the same origin were different，all showed binder > wrapper and filler leaves. Comparing tobacco leaf samples for the same use but from different origins，the 3 indexes of tobacco leaf samples from Dehong and Pu’er were higher than those of Lincang tobacco samples，with more abundant microbial species. The microorganisms of cigar tobacco leaves from different producing areas were mainly bacteria，and the dominant phylum were Proteobacteria and Firmicutes. There were great differences in the dominant genera of tobacco leaves with different uses，with Klebsiella occupying a larger proportion of the cigar wrapper leaves from 3 origins，Pantoea dominated in the filler leaves from Lincang and Pu’er；and the dominant genera of the binder leaves from 3 origins were more diverse and abundant. The results of KEEG and COG function prediction analysis showed that the microbial functional metabolic pathways and functional types of 9 tobacco samples were basically the same，but the relative abundance was greatly different. KEEG function prediction metabolic pathways were mainly global and overview maps，carbohydrate metabolism，amino acid metabolism，and the COG function type prediction was mainly distributed in the unknown function，amino acid transport and metabolism，transcription， inorganic ion transport and metabolism，carbohydrate transport and metabolism. 【Conclusion】 The use of tobacco leaves is an important factor affecting the microbial diversity of cigar tobacco leaves in Yunnan，while the influence of producing area is relatively small，and the microbial richness of binder leaves is higher than that of cigar wrapper and filler leaves.