Intestinal Bacteria as Powerful Trapping Lifeforms for the Elimination of Radioactive Cesium

In March 2011, the accident at the Fukushima Daiichi Nuclear Power Plant caused diffuse radionuclides such as Cesium (Cs)-137 to enter the environment. Ever since this accident, Cs-137 contamination in foods has become a serious problem. In this study, we determined the concentrations of Cs-137 in the feces, urine, and ruminal contents of cattle, and demonstrated the possibility of the powerful elimination from the body by intestinal bacteria. The results revealed a high Cs-137 concentration in the feces, and it was even higher than that in skeletal muscle and other samples in several animals. Furthermore, intestinal bacteria were able to trap Cs-137, showing an uptake ratio range of 38–81% in vitro. This uptake appeared to be mediated through the sodium ion–potassium ion pump in the bacterial cell membrane, because the uptake ratio of Cs-137 was decreased in medium with a high potassium concentration. In addition, it was demonstrated that intestinal bacteria hindered the trapping of Cs-137 by the animal. Cattle’s feces showed high concentration of Cs-137 and intestinal bacteria trapped Cs-137. This study is the first report showing that intestinal bacteria contribute to the elimination of Cs-137 from the body.