# Alterations in gut microbial metabolic pathways following bariatric surgery assessed by 16S rRNA gene sequencing

## TL;DR

This study explores how gut microbes and their metabolic functions change in women who do or do not lose weight after bariatric surgery.

## Contribution

The study identifies specific microbial families and metabolic pathways associated with weight loss outcomes after bariatric surgery.

## Key findings

- Barnesiellaceae abundance was significantly lower in surgical groups compared to non-surgical groups.
- Certain metabolic pathways like PWY0–1241, PWY-5177, and PWY-5855 were upregulated in the weight-loss group.
- Microbial metabolic functions may better predict weight loss outcomes than diversity metrics.

## Abstract

Researchers have studied gut microbiota changes following bariatric surgery (BS), but not gut diversity and function in patients who fail to reduce weight. Stool samples were collected from three groups of women: 15 women who did not lose weight after BS (“Yes” group), 9 overweight women without surgery, and 8 slim women (“No” group). 16S ribosomal RNA gene sequencing and PICRUSt2 were used for the analysis. The surgery and control groups had equal alpha and beta diversity, perhaps due to the high proportion of overweight participants (n = 24). All groupings were dominated by Bacteroidota and Bacillota. Barnesiellaceae decreased with BS, although Streptococcaceae remained frequent in overweight people. The iron supplementation group had High abundance of Atopobiaceae and Prevotellaceae. Barnesiellaceae abundance was considerably lower in both surgical groups (with and without iron supplementation) than in the no-iron and no-surgery groups. The ornithine degradation and haem biosynthesis routes use different metabolites than the glycine super system. Finally, the “Yes” group significantly upregulated PWY0–1241, PWY-5177, and PWY-5855 signaling pathways. In conclusion, gut bacteria and metabolic functions may predict weight loss after surgery better than diversity markers. The requirement for orthogonal validation assays is suggested by pathway analysis outperforming diversity metrics.