Impact of Low-Dose Ionizing Radiation on the Composition of the Gut Microbiota of Mice

Although the importance of the gut microbiota in the maintenance of human health has been well established, little is known about the impact of low-dose ionizing radiation ([LDR]; exposure to a dose of less than 0.5 Gy of low linear energy transfer radiation such as γ- or X-rays) on the composition and functional role of the gut microbiota. The aim of the present study was to investigate and compare the composition of the gut microbiota in mice exposed to LDR. Male BALB/c mice were exposed to low-dose Co60 radiation. Fecal samples taken prior to and after irradiation were used for high-throughput sequencing of 16S rRNA gene sequence amplicons. We observed substantial changes in the composition of the gut microbiota, including alpha diversity and beta diversity, in mice exposed to LDR compared with the nonradiated control group. Moreover, at the genus level, the abundance of Clostridium, Helicobacter, and Oscilibacter increased, and those of Bacteroides and Barnesiella decreased, in a time-dependent manner in the radiated groups compared with the nonradiated control group. The functional metabolic pathway analysis indicated that Bacteroides spp. and members of the other genera that were found are predicted to play roles in bacterial toxin production, DNA repair, and Type II diabetes. Furthermore, these alterations in the gut microbiota were accompanied by changes in the abundance of multiple metabolites, which were predicted to be involved in multiple signaling pathways, including glucagon, central carbon metabolism, and type II diabetes. The possibility of microbiota-mediated pathophysiology resulting from LDR may be an as yet unrecognized hazard that merits further experimental examination. This study provides a conceptual and analytical foundation for further research into the chronic effects of LDR on human health, and points to potential novel targets for intervention to prevent the adverse effects of radiation.