VSG results in metabolic improvements in diet-induced obese mice and increases Lactobacillus richness in the duodenum. A. Experimental design and timeline (VSG n = 19, SHAM n = 10). B. Bodyweight. C. Cumulative food intake after surgery. D. Fat mass and lean mass measured using nuclear magnetic resonance (NMR). E. Intraperitoneal glucose tolerance test (I.P. GTT, 2 g/kg) and Area Under the Curve (AUC). Data are presented as means ± S.E.M. Two-way ANOVA with post-hoc Sidak test for multiple comparisons (Panel B–D and Panel E–I.P. GTT curve) and Student's t-test (Panel E-AUC) were used for significance assessments. ∗∗∗P < 0.001, ∗∗P < 0.01, ∗P < 0.05. F. Linear discriminant analysis (LDA) effect size (LEfSe) generated phylogenetic tree and LDA score of enriched bacterial taxa in the duodenum chyme samples (left) and mucosal samples (right) collected from mice that underwent VSG and sham surgery. Significantly enriched bacterial taxa (LDA score >2 of LEfSe) were labeled with indicated colors. Abbr. SHAM, sham surgery; VSG, vertical sleeve gastrectomy.