How Blue And Green Clays Kill Bacteria


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.
Morrison is the lead author of the paper reporting the discovery, which was published Jan. 8 in Nature Scientific Reports. Rajeev Misra, a microbiology professor in ASU’s School of Life Sciences (SOLS) is the third author of the paper. Morrison’s work in Misra’s laboratory gave insights into the mechanism by which clays work to kill bacteria. Both SESE and SOLS are units in the university’s College of Liberal Arts and Sciences.

A critical part of the investigation involved the use of ASU’s NanoSIMS, which is part of the National Science Foundation-supported Secondary Ion Mass Spectrometry Facility. The study also benefited from a variety of electron microscopes and X-ray equipment in the LeRoy Eyring Center for Solid State Science.

Read More: Sciencedaily

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