Effects Of Microbial Communities On Quality Of Tobacco Leaves In Different Storage Environments

In the ecological perspective,the aging of tobacco leaves is the degradation and dissipation process of tobacco leaves and a variety of microorganisms in the storage environment.In the storage ecosystem,the microorganisms,as a biological factor,play a vital role in the aging of tobacco leaves,on the one hand,the secretion of biological enzymes were used to catalyze the degradation of macromolecule organic matter and promote the transfer of elements in tobacco leaves,on the other hand,they can promote the production and accumulation of the fragrant precursor material.Aging tobacco leaves are the result of the interaction of many microbial populations,rather than a single or several kinds of microorganisms.Based on the idea of microbial ecology,the diversity and community composition of tobacco microbes and three different warehouses,Guiyang warehouse,Tanchang warehouse and Maotai Ziyun warehouse,which with three different storages environments microbes were studied by using classical plate isolation and high-throughput sequencing combined with biological enzyme activity,aroma substances,conventional chemicals,sensory evaluation and other indicators to evaluate the effects of microbial community on the quality of tobacco.The following results are obtained:(1)Before and after the storage of tobacco leaves,the environmental microbial ecosystems are significantly disturbed.With the increase of aging time,it gradually tends to be stable and seasonal fluctuation is smaller.In the aspect of diversity,the microorganisms in the Maotai Ziyun warehouse are superiority in quantity and variety.In the aspect of microbial community composition,there was significant difference between Moutai Ziyun warehouse and the other two warehouses.The dominant microorganisms in Guiyang warehouses are Aspergillus,Penicillium,Cladosporium and Bacillus and the dominant microorganisms in Tanchang warehouses are Aspergillus,Penicillium,Bacillus,Stenotrophomonas and Alcaligenes.However,the dominant microorganisms in Moutai Ziyun warehouse are Aspergillus,Fusarium,Cladosporium,Bacillus,Ochrobactrum,Alcaligenes,Delftia,Stenotrophomonas and Streptomyces.There is a correlation between microbes in storage environment and microbes in tobacco leaves.(2)The result of high-throughput sequencing showed that there were significant differences in microbial diversity among different storages,and the fungal diversity of tobacco leaves in Tanchang warehouses was the most abundant,followed by Guiyang warehouses and the lowest was Moutai Ziyun warehouse.The bacteria diversity in Guiyang warehouses was the most abundant,followed by the Tanchang warehouse,the lowest is the Tanchang warehouses.With the increase of aging time,the fungal community structure of Guiyang warehouses was the greatest changed,while the bacterial community structure in Maotai Ziyun warehouses was the greatest changed.The fungal and bacterial community composition in different storages were basically the same,and the Ascomycota and Proteobacteria were dominant.During the microorganisms of tobacco leaves in Guiyang warehouses,Gammaproteobacteria and Eurotiomycetes were the dominant classes,Enterobacteriaceae,Monascaceae and Cystofilobasidiaceae were the dominant families,Pseudomonas and Xeromyces were the dominant genera.The dominant classes of the tobacco leaves microorganisms in Tanchang warehouses were Gammaproteobacteria,Microbotryomycetes and Eurotiomycetes,the dominant families were Enterobacteriaceae and Incertae sedis Sporidiobolales,the dominant genera were Pseudomonas and Rhodotorula.The dominant classes of the tobacco leaves microorganisms in Maotai Ziyun warehouses were Gammaproteobacteria and Eurotiomycetes,the dominant families were Enterobacteriaceae and Monascaceae,the dominant genera were Pseudomonas and Xeromyces.Cultivable tobacco microorganism accounted for 5~9% of the total number of microorganisms,Penicillium,Aspergillus and Bacillus were the dominant genera.Tobacco ecosystem has certain selectivity to the microbial storage environment.(3)The microbial community structure of Maotai Ziyun warehouses was different from Guiyang warehouses and Tanchang warehouses,especially the bacteria community was the most obvious.In addition,There were significant differences among the three groups,such as the Eurotiomycetes,Monasciaceae of Ziyun warehouses,and Microbotryomycetes,Sporidiobolales,Schizophyllaceae,Plectosphaerellaceae and Alcaligenaceae of Tanchang warehouses.The ecological environment has an important effect on the microbial community composition and structural change of the tobacco leaves.(4)In the process of tobacco aging,a microbial community ecological of "survival of the fittest" will happen,the bacteria groups were changed from Proteobacteria to Firmicutes and Actinobacteria,and the role of Firmicutes and Actinobacteria were gradually strengthened,while it was not obvious in fungi.The relative abundance of dominant populations was inconsistent.With the increase of aging time,the number of microorganism in tobacco leaves increased first and then decreased,and reached the maximum at 3 months;The proportion of dominant population decreased first and then increased,the fungi reached the lowest value at 12 months and the bacteria reached the lowest value at 18 months;Microbial interaction mainly happened on the aged 18 months ago,and the dynamic changes of microorganisms were associated with the gradual degradation of tobacco compounds.(5)Principal component analysis(PCA)and variance analysis showed that there were differences in bio-enzyme activity,aroma constituents,conventional chemical substances and sensory evaluation between tobacco leaves of different storages.And the results showed that tobacco leaves of Maotai Ziyun warehouse have a large variation,got the best effect of aging,the optimal aging time was 12 to 18 months.Through the correlation analysis and redundancy analysis(RDA)show that the Firmicutes,Gemmatimonadetes,Proteobacteria,Ascomycota,Basidiomycota,Zygomycota and other dominant microorganisms were associated with the tobacco chemical substances,aroma,sensory evaluation and other quality indicators,were important microbial groups affecting the quality of tobacco aging,and the effect of the dominant fungal groups overall was higher than the dominant bacterial groups.The microbial diversity of aging tobacco leaves was rich and contain many uncultured microorganisms,which support the development of tobacco microbial resources.The analysis of relation between microbial community and chemical indicators in tobacco leaves showed that the microbial community was closely related to the quality of tobacco leaves,which provided a theoretical reference for regulation of tobacco quality by microorganisms.The aging effect of tobacco of Maotai Ziyun was significantly better than that of the other two,which indicated that the ecological environment of Maotai Town was beneficial to the aging of tobacco leaves.