烤烟品种与等级特异性代谢特征及烟碱降解菌对烟叶品质影响

Metabolic characteristics of different flue-cured tobacco varieties and grades and quality improvement effects of nicotine-degrading bacteria on tobacco leaves

摘要:

目的 探究不同品种和不同等级烤烟的代谢物差异，以及烟碱降解菌对不同等级烟叶品质的影响。方法 基于非靶向代谢组学技术对‘云烟87’和‘云烟97’品种的烤烟，以及B2F和C2F等级烤烟发酵后的代谢产物进行鉴定与分析，同时探究烟碱降解菌对不同等级烤烟烟叶品质的影响。结果 不同品种、不同等级烤烟烟叶之间的代谢物差异显著。‘云烟87’和‘云烟97’样品之间鉴定出131种差异代谢物，B2F与C2F等级之间鉴定出138种差异代谢物，差异代谢物主要包括氨基酸、黄酮类化合物、生物碱及其衍生物等。不同品种和等级差异代谢物的KEGG代谢途径及富集程度分析结果均显示，黄酮和黄酮类生物合成代谢通路最为显著。此外，本研究从烟草种植土壤中筛选分离到2株能以烟碱为唯一碳源和氮源生长的假单胞菌属(Pseudomonas sp.) TR9和TR14。将这2株菌株组合接种于不同等级烟叶后能够显著降低低等级烟叶中的烟碱、蛋白质和淀粉含量。结论 本研究揭示了品种和等级通过黄酮代谢通路影响烟叶品质的机制，并验证了烟碱降解菌对低等级烟叶的改良效果，为烤烟品质改良和发酵工艺优化提供了理论支持。

Abstract:

Objective To investigate the metabolite differences among different varieties and grades of flue-cured tobacco, as well as the impacts of nicotine-degrading bacteria on the quality of different grades of tobacco leaves.Methods This study employed untargeted metabolomics to identify and analyze metabolites in fermented tobacco leaves of ‘Yunyan 87’ and ‘Yunyan 97’, specifically B2F and C2F grades, while also examining the influences of nicotine-degrading bacteria on the quality of different grades of flue-cured tobacco leaves.Results There were significant metabolite differences between tobacco leaves of different varieties and grades. A total of 131 differential metabolites were identified between the samples of ‘Yunyan 87’ and ‘Yunyan 97’, while 138 differential metabolites were identified between B2F and C2F grades. These differential metabolites mainly included amino acids, flavonoids, alkaloids, and their derivatives. Analysis of KEGG metabolic pathways and enrichment levels for differential metabolites across different varieties and grades all indicated that flavonoid biosynthesis pathways were the most prominent. Furthermore, this study successfully isolated two bacterial strains, Pseudomonas sp. TR9 and Pseudomonas sp. TR14, from tobacco-cultivated soil, both capable of utilizing nicotine as the sole carbon and nitrogen source. Inoculation of the strain combination into different grades of tobacco leaves significantly reduced the content of nicotine, protein, and starch in lower-grade tobacco leaves.Conclusion This study reveals the mechanism by which varieties and grades affect the quality of tobacco leaves through the flavonoid biosynthesis pathways, and verifies the improvement effects of nicotine-degrading bacteria on low-grade tobacco leaves, providing theoretical support for the improvement of flue-cured tobacco quality and the optimization of fermentation processes.