Overfeeding, Agavins, and Dietary Fat: Factors that Modulate the Zebrafish Gut Microbiota

This study investigates the effects of low-fat diet overfeeding on biological parameters and gut microbiota in adult male zebrafish (<i>Danio rerio</i>). Zebrafish were assigned to four treatment groups: two received control low-fat diets (LF: low-fat; LFA: low-fat with 5% agavins), while the others were overfed these diets (LFO: overfed low-fat; LFAO: overfed low-fat with agavins). Results indicated that low-fat overfeeding led to weight gain and increased biometric indices indicative of overweight and obesity, alongside notable changes in gut microbiota. Agavin supplementation significantly reduced food intake (<i>p</i> < 0.05) and decreased body weight and fat in the overfed groups. Multivariate analyses (permutational multivariate analysis of variance and analysis of similarities) revealed that the LFAO treatment significantly influenced gut microbiota composition, as assessed through 16S ribosomal RNA gene sequencing (V3 region). Noticeable differences in bacterial composition were observed between LFA and LFAO, especially regarding the genera <i>Aeromonas</i>, <i>Paraburkholderia</i>, and an unclassified genus from the Fusobacteriaceae, which contributed to these differences. While dietary factors, specifically agavins, exerted a limited influence on the composition of gut microbiota, the feeding regimen demonstrated a considerable effect.