Administration of Probiotics Enriched Gut Bacteria Diversity and Glycan Degrading Ability in Small Bowel Transplantees

Background: The role of probiotics among small bowel transplantation (SBT) patients is intriguing because bacteria reside in the transplanted organ per se and hosts’ immune functions are inevitably compromised. Glycans are the primary nutritional source for microbes in the human gut. Analysis of glycan degradation by the gut microbiota is an important tool for advancing our understanding of bacterial metabolism in the gut.

Objectives: The aim of this study was to quantify glycan processing capabilities and investigate the relationship between the changes of gut microbiota and glycan metabolism before and after probiotics treatment.

Methods: The SBT patients without obvious sepsis, weaning from parenteral nutrition (PN) and normal oral intake were enrolled in this study. During the study period, they were receiving standard doses of Tacrolimus and steroids. These SBT patients received oral probiotics (CBM588: Clostridium butyricum MIYAIRI 588, 1.5 ×10⁹ CFU/day) for 1 month. Fecal samples were collected at before, 1 week and 1 month after oral probiotics therapy. Next-generation sequencing targeting 16S ribosomal sequences from fecal materials was used to evaluate gut microbiota and glycan degradation potency, respectively. We compare the changes of microbiota and glycan degrading capabilities before and after probiotics treatment.

Results: Significant shifts of bacteria compositions were found after one month of CBM588 ingestions. Specifically at the family level, Bacteroidaceae increased with a substantial boost from 4% to 21% but Enterobacteriaceae decreased by a large margin from 41% to 34%. Functional inference with 16S-based microbiome extrapolations suggested characteristic enhancement of glycan degrading capabilities with CBM588 ingestions. Metagenomes from shotgun sequencing confirmed the conjecture, showing both diversified capabilities and increased quantities of carbohydrate (glycan)-active genes. The improvements spread beyond the enzyme categories directly offered by the CBM588 genome.

Conclusions: In sum, CBM588-enhanced glycan-processing capabilities well exemplified a metabolic driver potential of probiotics upon the bacteria ecosystem in human bowels.