Modulation of Gut Microbiota of Overweight Mice by Agavins and Their Association with Body Weight Loss.

Hakdong Shin,Mercedes López,Alicia Huazano-García

doi:10.3390/nu9090821

Abstract

Agavins consumption has led to accelerated body weight loss in mice. We investigated the changes on cecal microbiota and short-chain fatty acids (SCFA) associated with body weight loss in overweight mice. Firstly, mice were fed with standard (ST5) or high-fat (HF5) diet for five weeks. Secondly, overweight mice were shifted to standard diet alone (HF-ST10) or supplemented with agavins (HF-ST + A10) or oligofructose (HF-ST + O10), for five more weeks. Cecal contents were collected before and after supplementation to determine microbiota and SCFA concentrations. At the end of first phase, HF5 mice showed a significant increase of body weight, which was associated with reduction of cecal microbiota diversity (PD whole tree; non-parametric t test, p < 0.05), increased Firmicutes/Bacteroidetes ratio and reduced SCFA concentrations (t test, p < 0.05). After diet shifting, HF-ST10 normalized its microbiota, increased its diversity, and SCFA levels, whereas agavins (HF-ST + A10) or oligofructose (HF-ST + O10) led to partial microbiota restoration, with normalization of the Firmicutes/Bacteroides ratio, as well as higher SCFA levels (p < 0.1). Moreover, agavins noticeably enriched Klebsiella and Citrobacter (LDA > 3.0); this enrichment has not been reported previously under a prebiotic treatment. In conclusion, agavins or oligofructose modulated cecal microbiota composition, reduced the extent of diversity, and increased SCFA. Furthermore, identification of bacteria enriched by agavins opens opportunities to explore new probiotics.

Highlights

Agavins are branched neo-fructans found in Agave plants, which contain a mixture of β(2-1) and β(2-6) linkages [1,2]
Plants from two to four years old have a high content of agavins with low degree of polymerization (DP) and simpler chemical structures, while plants from five to seven years old contain a large proportion of high-DP agavins and highly-complex chemical structures [3]
short chain fatty acids (SCFA) are very important because they reduce body weight gain, through G-protein-coupled receptors (GPRs), influencing the secretion of hormones involved in Nutrients 2017, 9, 821; doi:10.3390/nu9090821

Summary

Introduction

Agavins are branched neo-fructans found in Agave plants, which contain a mixture of β(2-1) and β(2-6) linkages [1,2]. Agavins act as prebiotics inducing benefits to host health by providing specific changes in the composition and/or activity of the gut microbiota [4]. Due to their structural complexity, endogenous gastrointestinal enzymes cannot degrade agavins during their passage through the stomach and the small intestine; so they reach both the cecum and colon, where they are fermented by saccharolytic microbiota present in these sites, producing short chain fatty acids (SCFA), mostly acetate, propionate, and butyrate. SCFA are very important because they reduce body weight gain, through G-protein-coupled receptors (GPRs), influencing the secretion of hormones involved in Nutrients 2017, 9, 821; doi:10.3390/nu9090821 www.mdpi.com/journal/nutrients

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