尽管肥胖外科手术后心血管代谢结局的改善，其对结直肠癌（CRC）风险的长期影响仍不确定。与此同时，肥胖外科手术对宿主微生物组的影响及其与疾病结局的关系开始引起人们的关注。因此，我们研究了Roux-en-Y胃旁路术（RYGB）和垂直袖状胃切除术（VSG）对硫化物还原和丁酸盐产生细菌模式的影响，这些细菌被假设在肥胖外科手术后调节CRC风险。在这个单中心横断面研究中，我们纳入了15例严重肥胖的术前患者和经过RYGB（n=16）或VSG（n=10）手术的患者，分别为术后中位数（范围）25.6（9.9-46.5）个月。使用宏基因组测序鉴定了粪便细菌和参与丁酸盐和硫化物代谢的酶的DNA丰度。通过线性判别分析（LDA）效应大小（LEfSe）方法量化了术前和术后RYGB或VSG组之间的差异。我们的样本以女性为主（87%），年龄中位数（范围）为46（23-71）岁。术后RYGB和VSG患者的粪便硫化物还原菌的DNA丰度高于术前对照组（LDA=1.3-4.4，p<.05）。最显著的富集是RYGB后的大肠埃希菌、贫酸菌和A.细胞酸菌，以及VSG后的A.细胞酸菌、S.前庭球菌和V.小型球菌。至于丁酸盐产生菌，RYGB术后R.痰质更丰富，而B.病保和A.基尔德斯与术前相比较少。B.病保在VSG术后与术前相比也较少。与这些发现一致，我们的分析显示术后肥胖外科手术，特别是RYGB，导致硫化物还原酶更加丰富。丁酸盐产生酶的DNA丰度在RYGB术后较低。总之，两种最常用的肥胖外科手术，RYGB和VSG，与潜在涉及CRC风险的微生物组模式相关。未来需要进一步研究来验证和理解这些微生物组变化对肥胖外科手术后CRC风险的影响。

Despite improved cardiometabolic outcomes following bariatric surgery, its long-term impact on colorectal cancer (CRC) risk remains uncertain. In parallel, the influence of bariatric surgery on the host microbiome and relationships with disease outcomes is beginning to be appreciated. Therefore, we investigated the impact of Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) on the patterns of sulfide-reducing and butyrate-producing bacteria, which are hypothesized to modulate CRC risk after bariatric surgery. In this single-center, cross-sectional study, we included 15 pre-surgery subjects with severe obesity and patients who are at a median (range) of 25.6 (9.9-46.5) months after RYGB (n = 16) or VSG (n = 10). The DNA abundance of fecal bacteria and enzymes involved in butyrate and sulfide metabolism were identified using metagenomic sequencing. Differences between pre-surgery and post-RYGB or post-VSG cohorts were quantified using the linear discriminant analysis (LDA) effect size (LEfSe) method. Our sample was predominantly female (87%) with a median (range) age of 46 (23-71) years. Post-RYGB and post-VSG patients had a higher DNA abundance of fecal sulfide-reducing bacteria than pre-surgery controls (LDA = 1.3-4.4, p < .05). The most significant enrichments were for fecal E. coli, Acidaminococcus and A. finegoldii after RYGB, and for A. finegoldii, S. vestibularis, V. parvula after VSG. As for butyrate-producing bacteria, R. faecis was more abundant, whereas B. dentium and A. hardus were lower post-RYGB vs. pre-surgery. B. dentium was also lower in post-VSG vs. pre-surgery. Consistent with these findings, our analysis showed a greater enrichment of sulfide-reducing enzymes after bariatric surgery, especially RYGB, vs. pre-surgery. The DNA abundance of butyrate-producing enzymes was lower post-RYGB. In conclusion, the two most used bariatric surgeries, RYGB and VSG, are associated with microbiome patterns that are potentially implicated in CRC risk. Future studies are needed to validate and understand the impact of these microbiome changes on CRC risk after bariatric surgery.