Dysbiosis of gut microbiota by dietary exposure of three graphene-family materials in zebrafish (Danio rerio)

The increasing application and subsequent mass production of graphene-family materials (GFMs) will lead to greater possibilities for their release into the environment. Although GFMs exhibit toxicity toward various aquatic organisms, little information is available on their influence on gut microbiota of aquatic organism. In this study, zebrafish were fed diets containing three GFMs, namely, monolayer graphene powder (GR), graphene oxide nanosheet (GO) and reduced graphene oxide powder (rGO), or appropriate control for 21 days. The gut bacterial communities were then characterized for comparison of the exposure effects of each GFM. Alterations of the intestinal morphology and oxidative stress indicators were also examined. The results showed GFMs led to different inflammatory responses and significantly altered the relative composition of the gut bacterial species by increasing the relative abundance of Fusobacteria and the genus Cetobacterium and Lactobacillus and decreasing the abundance of Firmicutes and the genus Pseudomonas; GR caused marked shifts in the diversity of the gut microbiota. The GFMs also altered the intestinal morphology and antioxidant enzyme activities by inducing more vacuolation and generating more goblet cells. Our findings demonstrate that GFM exposure poses potential health risks to aquatic organisms through alteration of the gut microbiota. (C) 2019 Elsevier Ltd. All rights reserved.