Since prehistoric times, clays have been used by people for medicinal purposes. Whether by eating it, soaking in a mud bath, or using it to stop bleeding from wounds, clay has long been part of keeping humans healthy. Certain clays have also been found with germ-killing abilities, but how these work has remained unclear.
A new discovery by Arizona State University scientists shows exactly how two specific metallic elements in the right kinds of clay can kill troublesome bacteria that infect humans and animals.
“We think of this mechanism like the Trojan horse attack in ancient Greece,” said Lynda Williams, a clay-mineral scientist at ASU’s School of Earth and Space Exploration (SESE). “Two elements in the clay work in tandem to kill bacteria.”
She explained, “One metallic element — chemically reduced iron, which in small amounts is required by a bacterial cell for nutrition — tricks the cell into opening its wall. Then another element — aluminum — props the cell wall open, allowing a flood of iron to enter the cell. This overabundance of iron then poisons the cell, killing it as the reduced iron becomes oxidized.”
“It’s like putting a nail in the coffin of the dead bacteria,” said Keith Morrison, Williams’ former doctoral student, who is now at Lawrence Livermore National Laboratory.
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