Human intestinal microbiota is affected by the exogenous microenvironment. This study aimed to determine the effects of cigarettes and alcohol on the gut microbiota of healthy men. In total, 116 healthy male subjects were enrolled and divided into four groups: non-smoking and non-drinking (Group A), smoking only (Group B), drinking only (Group C), and smoking and drinking combined (Group D). Fecal samples were collected and sequenced using 16S rRNA to analyze the microbial composition. Short-chain fatty acid (SCFAs) levels in feces were determined by gas chromatography. We found that cigarette and alcohol consumptions can alter overall composition of gut microbiota in healthy men. The relative abundances of phylum Bacteroidetes and Firmicutes and more than 40 genera were changed with cigarette and alcohol consumptions. SCFAs decreased with smoking and alcohol consumption. Multivariate analysis indicated that when compared with group A, group B/C/D had higher Bacteroides, and lower Phascolarctobacterium, Ruminococcaceae_UCG-002, Ruminococcaceae_UCG-003, and Ruminiclostridium_9 regardless of BMI and age. Additionally, the abundance of Bacteroides was positively correlated with the smoking pack-year (r = 0.207, p < 0.05), the abundance of predicted pathway of bacterial toxins (r = 0.3672, p < 0.001) and the level of carcinoembryonic antigen in host (r = 0.318, p < 0.01). Group D shared similar microbial construction with group B, but exerted differences far from group C with lower abundance of Haemophilus. These results demonstrated that cigarette and alcohol consumption separately affected the intestinal microbiota and function in healthy men; furthermore, the co-occurrence of cigarette and alcohol didn’t exacerbate the dysbiosis and cigarette played the predominated role on the alteration.

人肠微生物群受外源微环境影响。这项研究旨在确定香烟和酒精对健康男性肠道菌群的影响。总共纳入了116名健康男性受试者，分为四组：不吸烟和不饮酒（A组），仅吸烟（B组），仅吸烟（C组）和吸烟与饮酒相结合（D组） 。收集粪便样品并使用16S rRNA进行测序以分析微生物组成。通过气相色谱法测定粪便中的短链脂肪酸（SCFA）水平。我们发现，吸烟和饮酒可以改变健康男性肠道菌群的整体组成。拟杆菌门和硬毛门的相对丰度超过40属改变了香烟和酒精的消费量。随着吸烟和饮酒，SCFA降低。多变量分析表明，与B组相比，B / C / D组的拟杆菌含量较高，而杆菌杆菌，Ruminococcaceae_UCG-002，Ruminococcaceae_UCG -003和Ruminiclostridium_9的杆菌含量较低。另外，拟杆菌的丰度与吸烟年数（r = 0.207，p <0.05），细菌毒素的预测途径的丰度（r = 0.3672，p <0.001）和宿主中癌胚抗原水平呈正相关。 （r = 0.318，p<0.01）。D组与B组具有相似的微生物结构，但与C组相比差异很大，嗜血杆菌的丰度较低。这些结果表明，吸烟和饮酒分别影响健康男性的肠道菌群和功能。此外，香烟和酒精的并存并没有加剧这种病的发生，香烟在这种改变中起主要作用。