Gut microbiota adaptation after weight loss by Roux-en-Y gastric bypass or sleeve gastrectomy bariatric surgeries

Background: Gut microbiota could be involved in the metabolic improvement after surgery. Objective: The aim of the present study was to evaluate the short-term evolution of the gut microbiome after different bariatric surgery procedures and their functionality and relate it with obesity resolution. Setting: University hospital, Spain. Methods: We studied 28 patients with severe obesity; 14 underwent a Roux-en-Y gastric bypass (RYGB) and 14 underwent laparoscopic sleeve gastrectomy (SG). All patients were examined before and 3 months after the correspondent bariatric surgery. Gut microbiome profile was assessed by the sequencing of amplicons from the 16S rDNA gene by next-generation sequencing. Results: Gut microbiota profiles significantly differed between surgical procedures. RYGB suffered the largest changes in the microbiota population. SG and RYGB differed in their profiles with higher levels of Akkennansia, Eubacterium, Haemophilus, and Blautia for SG, while Veillonella, Slackia, Granucatiella, and Acidaminococcus occurred with greater levels in RYGB. RYGB microbiota changes were reflected also at the level of functionality, especially in pathways related to environmental adaptation. A biomarker discovery analysis revealed the genus Blautia as characteristic in SG, while Veillonella was of RYGB. Conclusion: Our study shows a shift of the gut microbiome after a bariatric surgery in a procedure related manner. Gut microbiome changes are related to the adaptation to the changing gut environment and could be related to the pH fluctuations. (C) 2019 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.