Abstract: To screen a strain of aroma⁃enhancing bacteria that can be used for low⁃grade tobacco leaves，strains were isolated from tobacco leaves，Damask roses，Oolong tea leaves，and Osmanthus fragrans，and re⁃screened by sensory scores. After single factor optimization of fermentation conditions，headspace solid⁃phase microextraction⁃gas chromatography⁃mass spectrometry（HS⁃SPME⁃GC⁃MS） and multivariate statistical methods were further used to analyze the changes of volatile metabolites and significant differential metabolic pathways when the strain was applied to the liquid fermentation of low⁃grade tobacco leaves. The results showed that 119 strains were isolated from tobacco leaves，Damask roses，tea leaves，and Osmanthus fragrans，of which 9 strains produced obvious aroma. Among them，MG⁃1（the first strain isolated from the Damask rose sample collected in Dali City，Yunnan Province） achieved the highest total sensory score for cigarette sensory evaluation（54.00 points），which was 8.30% higher than that of the control group without bacterial inoculation（49.86 points）. It was identified as Enterobacter asburiae by molecular analysis. The optimal liquid fermentation conditions of the strain were determined as follows：inoculation amount 3%，fermentation time 12 h，liquid volume 100 mL，shaking speed 180 r/min. A total of 1 583 volatile metabolites were identified by HS⁃SPME⁃GC⁃MS. Multivariate statistical analysis showed that 197 of them were differential metabolites（132 up⁃regulated and 65 down⁃regulated），with an up⁃regulation ratio of 67. 0%. The differential metabolites with variable importance in projection（VIP） values in the top 40 and fold change（FC）≥2 or FC≤0. 5 were further screened. After fermentation，the contents of aroma components such as 6⁃methyl⁃5⁃hepten⁃2⁃ol（citrus aroma），myrcene（citrus aroma），dimethyl succinate（fruit aroma），phenylacetaldehyde（almond aroma），phenylethyl alcohol（rose aroma） and safranal（spicy and floral aroma） were significantly up⁃regulated，while the contents of irritant substances such as allyl isothiocyanate were significantly down⁃regulated. Further KEGG pathway analysis showed that the differential metabolites were mainly enriched in six pathways：phenylalanine metabolism，biosynthesis of various plant secondary metabolites，microbial metabolism in diverse environments，degradation of aromatic compounds，metabolic pathway and biosynthesis of secondary metabolites.Among them，biosynthesis of various plant secondary metabolites and biosynthesis of secondary metabolites were significantly up⁃regulated，while metabolic pathway，degradation of aromatic compounds and microbial metabolism in diverse environments were significantly down⁃regulated.In summary，the liquid fermentation of Enterobacter asburiae MG⁃1 can effectively improve the aroma quality of the extract of low⁃grade tobacco leaves，and has a clear potential for aroma enhancement，which provides a theoretical basis for the improvement of the quality and efficiency of low⁃grade tobacco leaves.

摘要： 为筛选一株可用于低次烟叶的增香菌，首先分别从烟叶、大马士革玫瑰、乌龙茶叶、桂花中分离、初筛菌株，然后通过感官得分进行复筛。采用单因素优化发酵条件后，进一步采用顶空-固相微萃取-气相色谱-质谱联用技术（HS-SPME-GC-MS）与多元统计学方法，分析所筛菌株应用于低次烟叶液态发酵时挥发性代谢物的变化及差异显著代谢途径。结果表明，从烟叶、玫瑰、茶叶、桂花中共分离到119株菌株，有9株产生较为明显的香气。其中，MG-1（从云南省大理市大马士革玫瑰样品中分离得到的第1株菌）的卷烟感官评吸总分最高（54.00分），较不接菌的对照组（49.86分）提升8.30%，该菌株经分子鉴定为阿氏肠杆菌（Enterobacter asburiae）。该菌株的最优液态发酵条件为接种量3%、发酵时间12 h、装液量100 mL、摇床转速180 r/min。利用HS-SPME-GC-MS共鉴定出1 583种挥发性代谢物，多元统计分析显示，其中197种为差异代谢物（上调132种，下调65种），上调比例为67.0%。进一步筛选变量投影重要性（VIP）值前40且倍数变化（FC）≥2或FC≤0.5的差异代谢物，其中发酵后6-甲基-5-庚烯-2-醇（柑橘清香）、月桂烯（柑橘清香）、琥珀酸二甲酯（果香）、苯乙醛（杏仁香）、苯乙醇（玫瑰香）、藏红花醛（辛香、花香）等香气成分含量均显著上调，而异硫氰酸烯丙酯等刺激性化合物含量显著下调。进一步的KEGG通路分析显示，差异代谢物主要富集到苯丙氨酸代谢、植物次生代谢产物生物合成、多样化环境中微生物代谢、芳香族化合物降解、代谢途径以及次生代谢物生物合成等6个通路。其中，植物次生代谢产物生物合成和次生代谢物生物合成通路显著上调，而代谢途径、芳香族化合物降解及多样化环境中微生物代谢相关通路显著下调。综上，阿氏肠杆菌MG-1液态发酵能有效提升低次烟叶浸提液香气品质，具有明确的增香应用潜力，为低次烟叶的提质增效提供了理论依据。

关键词: 低次烟叶, 阿氏肠杆菌, 液态发酵, 非靶向代谢组学, 烟叶增香