Researchers from the University of Delaware (UD) have discovered a soil microbe that mobilizes an "iron shield" to block the uptake of arsenic in rice. Arsenic is toxic, and chronic exposure to it has been linked to cancer, heart disease and diabetes.

The soil microbe identified by the team is named "EA106", found among the roots of a North American variety of rice grown commercially in California. As rice is grown underwater, it takes in 10 times more arsenic than other cereal grains, such as wheat and oats. The researchers found that EA106 mobilizes iron, which competes with the arsenic, effectively blocking arsenic's pathway. Harsh Bais, who led the UD team explains, "An iron plaque forms on the surface of the roots that does not allow arsenic to go up into the rice plant."

The team conducted the study with hundreds of rice plants, some grown in soil, others grown hydroponically. Inoculations with EA106 improved the uptake of iron at the plant roots, while reducing the accumulation of toxic arsenic in the plant shoots.

For more details, read the news release at the UD website.

Figure: Clumps of bacteria (soil microbe EA106) and iron plaque begin forming on the roots of a rice plant. This "iron shield" blunts the uptake of arsenic. Image by Venkatachalam Lakshmanan and Deepak Shantharaj taken with the scanning electron microscope (SEM), UD Bioimaging Center.