Microbiome community structure is intimately involved in key biological functions in the gastrointestinal (GI) system including nutrient absorption and lipid metabolism. Recent evidence suggests that disruption of the GI microbiome is a contributing factor to metabolic disorders and obesity. Poor diet and chemical exposure have been independently shown to cause disruption of the GI microbiome community structure and function. We hypothesized that the addition a chemical exposure to overfeeding exacerbates adverse effects on the GI microbiome community structure and function. To test this hypothesis, adult zebrafish were fed a normal feeding regime (Control), an overfeeding regime (OF), or an overfeeding regime contaminated with diethylhexyl phthalate (OF + DEHP), a suspected obesogen-inducing chemical. After 60 days, fecal matter was collected for sequencing, identification, and quantification of the GI microbiome using the 16s rRNA hypervariable region. Analysis of beta diversity indicated distinct microbial profiles between treatments with the largest divergence between Control and OF + DEHP groups. Based upon functional predictions, OF + DEHP treatment altered carbohydrate metabolism, while both OF and OF + DEHP affected biosynthesis of fatty acids and lipid metabolism. Co-occurrence network analysis revealed decreases in cluster size and a fracturing of the microbial community network into unconnected components and a loss of keystone species in the OF + DEHP treatment when compared to Control and OF treatments. Data suggest that the addition of DEHP in the diet may exacerbate microbial dysbiosis, a consequence that may explain in part its role as an obesogenic chemical.

微生物组的群落结构与胃肠道（GI）系统的关键生物学功能密切相关，包括营养吸收和脂质代谢。最近的证据表明，胃肠微生物群的破坏是导致代谢紊乱和肥胖的一个因素。不良饮食和化学暴露已独立显示会导致GI微生物组群落结构和功能的破坏。我们假设过量摄入化学物质会加重对胃肠微生物群的结构和功能的不利影响。为了验证这一假设，给成年斑马鱼喂食了正常的喂食方案（对照），过量喂食方案（OF）或被邻苯二甲酸二乙基己酯（OF + DEHP）污染的过量喂食方案，这是一种怀疑引起肥胖的化学物质。60天后，使用16s rRNA高变区，收集粪便用于GI微生物组的测序，鉴定和定量。对β多样性的分析表明，在对照组与OF + DEHP组之间差异最大的是治疗之间的微生物谱。根据功能预测，OF + DEHP处理会改变碳水化合物的代谢，而OF和OF + DEHP都会影响脂肪酸的生物合成和脂质代谢。共存网络分析显示，与对照组和OF处理相比，OF + DEHP处理的簇大小减小，微生物群落网络破裂成未连接的成分，并且梯形菌种损失。数据表明，饮食中添加DEHP可能会加剧微生物营养不良，