Effects of Triclosan Exposure on the Gut Microbiome in Zebrafish

Abstract

Background/Aim Triclosan (TCS) is a widely used antibacterial agent in personal care products and ubiquitous in environment. As gut microbiota is known important for health, it is unclear whether TCS exposure may affect gut microbiota . This study aimed to examine the effects of early life long-term exposure to TCS and concurrent short-term exposure on gut microbiota in zebrafish. Methods Zebrafish fertilized eggs were cultured in TCS concentrations of 0 (Dimethyl Sulphoxide, DMSO control), 0.03, 0.3, 3, 30, 100, and 300 ng/mL from 0 to 120 days post fertilization (dpf) to examine its early life exposure effect. At 120 dpf, intestine samples were collected for analysis of gut microbiota based on the V3-V4 hypervariable regions of the 16S ribosomal RNA gene. We also exposed adult zebrafishes to TCS for 7 days to examine its short-term effect on gut microbiota of adult zebrafish. Results In exposure to TCS for 0-120 pdf , compared with those in DMSO control group, gut microbiota of zebrafish at TCS 300 ng/mL had 54.5 lower mean number of operational taxonomic units (OTUs) (mean ± SE, 71.29 ± 11.22 vs. 125.75 ± 2.39, p = 0.003), 41.40 lower Chao index (p = 0.03), and 34.10 lower ace index (p = 0.006), with lower relative abundance in Proteobacteria, Planctomycetes and Cyanobacteria and CKC4, but higher abundance in Bacteroidetes, at phylum level, and lower relative abundance in Acinetobacter, Cyanobacteria_norank, Hyphomicrobium, Methylobacterium, Sphingomonas, but higher abundance in CKC4_norank, Aeromonas, Staphylococcus, Prevotella and Bacteroides, at genus level. The short-term 7-day TCS exposure was not associated with the alpha or beta diversity of gut microbiota in adult zebrafish. Conclusions Early life exposure to high TCS concentration may lower diversity and richness of gut microbiota, and altered its composition in zebrafish. Such effect was not observed for short-term TCS exposure in adult zebrafish.