**4.3 Laparoscopic adjustable gastric banding (LAGB)-gut microbiota**

To our knowledge gut microbiota changes, have not been studied after LAGB surgery [53].

#### **4.4 Biliopancreatic diversion (BPD)-gut microbiota**

BPD/DS rats have significantly different microbiota than SHAM animals. Decreased gut microbiota richness and diversity were observed in BPD/DS rats. Microbial profile analysis showed a major shift from presurgical Clostridialesdominated microbiota to high-concentration microbiota in *Bifidobacteriales* soon after surgery. After BPD/SD, the gut is divided into three functional segments: the alimentary limb, biliopancreatic limb, and common limb. *Bifidobacteriales* have a high content in the alimentary limb and common limb. But because the biliopancreatic limb contains a significant amount of *Actinomycetales*, it is different from the other two limbs. In BPD/DS, unlike RYGB, it was shown that *Bifidobacteriales* elevated significantly as represented by the increasing abundance of *the Bifidobacterium* genus. In the lower part of the intestine, the presence of nutrients, which is digestible, but undigested can change the microbiota. In BPD/ SD rats, changes in the gut microbiota were associated with the beneficial influence of malabsorption procedures. Increasing the proportion of *Bifidobacteriales* bacteria associated with the genus *Bifidobacterium* may have health benefits for the host. *Bifidobacterium* predominance in the microbiota can reduce low-grade inflammation. The positive outcomes of surgery may be because of gut microbiota modulation and more specifically increase in *Bifidobacterium* abundance throughout the gastrointestinal tract [54].
