雪茄茄芯烟叶工业二次发酵过程中细菌与真菌群落多样性变化分析

  目的  为分析茄芯烟叶在二次发酵过程中细菌和真菌群落多样性及菌群动态变化规律。  方法  以德雪三号初次发酵烟叶为试验材料，采用细菌16S rDNA和真菌ITS1的Illumina MiSeq高通量测序技术，分析烟叶二次发酵0、5、10、15和20 d时细菌和真菌群落结构及丰度信息。  结果  发酵0 d时细菌群落Chao1、ACE和Shannon指数最高，分别为423.38、424.40和4.67；发酵10 d时真菌群落Chao1和ACE指数最高，分别为85.82、89.49。基于门水平，随着发酵时间的增加，细菌从以变形菌门（Proteobacteria）为优势转变为以厚壁菌门（Firmicutes）为主，真菌主要优势菌门为子囊菌门（Ascomycota），相对丰度在71.61%~98.16%之间。基于属水平，葡萄球菌属（Staphylococcus）为整个发酵过程中的主要优势细菌属，在发酵15 d时相对丰度最大（91.25%）；次要优势细菌属由假单胞菌属（Pseudomonas）、马赛菌属（Massilia）等转变为芽孢杆菌属（Bacillus）、土地芽孢杆菌属（Terribacillus）；曲霉属（Aspergillus）为真菌绝对优势菌属，平均丰度达到87.40%。LEfSe分析结果表明，21种细菌在属水平上有显著性差异，6种真菌在科水平上有显著性差异。  结论  茄芯烟叶在二次发酵过程中细菌和真菌群落的丰富度和多样性随着发酵时间的增加总体呈降低趋势。在属水平上，不同发酵时间茄芯烟叶细菌和真菌群落组成结构相似，相对丰度有明显差异，Staphylococcus和Aspergillus为二次发酵过程中的主要优势菌属。 

Analysis of bacterial and fungal community diversity during industrial secondary fermentation of cigar core tobacco leaves

  Objective  This study aims to analyze the bacterial and fungal community diversity and the dynamic change of bacterial community during the secondary fermentation process of cigar core tobacco leaves.  Methods  Taking the primary fermentation of tobacco leaves of Dexue No.3 as the test material, the bacterial and fungal community structure and abundance information of bacterial and fungal during secondary fermentation at 0, 5, 10, 15 and 20 days were analyzed by the Illumina MiSeq high-throughput sequencing technology.  Results  The results showed that the abundance and diversity of bacterial and fungal communities during the secondary fermentation process of cigar core tobacco leaves were generally decreased. The bacterial communities Chao1, ACE and Shannon indices were the highest at 0d of fermentation, which were 423.38, 424.40 and 4.67, respectively. The Chao1 index and ACE index of fungal communities were the highest at 10d of fermentation, which were 85.82 and 89.49, respectively. In the phylum level, with the increase of fermentation time, the dominant bacteria phylum changed from Proteobacteria to Firmicutes. Ascomycota was the main dominant fungal phylum, with the relative abundance ranging between 71.61% and 98.16%. In the level of genera, Staphylococcus was the main dominant genus, and the relative abundance showed an overall upward trend with the increase of fermentation time, and the abundance was the largest (91.25%) at 15d; Secondary dominant bacteria were transformed from Pseudomonas, Massilia to Bacillus and Terribacillus; Aspergillus was an absolute dominant fungus with an average abundance of 87.40%. The results of LEfSe analysis showed that 21 species of bacteria had significant differences at the genus level and 6 species of fungi had significant differences at the family level.  Conclusion  The number and types of bacteria and fungi during the secondary fermentation process of cigar core tobacco leaves decreased. At the genus level, the composition of bacterial and fungal communities in cigar core tobacco at different fermentation times was similar, the relative abundance was obviously different, and Staphylococcus and Aspergillus were the main dominant bacteria in the secondary fermentation process.