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Behind Bleach

December 9, 2008

A listener asks: How does bleach kill germs?


How bleach kills germs….I’m Bob Hirshon and this is Science Update.

Today’s Why Is It question comes from listener Nate of Atlanta, Georgia. He’d like to know how household bleach kills germs. Well, Nate, a group of scientists at the University of Michigan recently discovered that chlorine bleach actually knocks out bacteria in the same way high temperature does. Molecular biologist Ursula Jakob says that harmful bacteria rely on their proteins to do function. But both heat and bleach cause their proteins to unfold and break down.

URSULA JAKOB (University of Michigan):
These proteins that lose their structure start to clump together to form these large aggregates in the cell.

She says this renders the bacteria harmless. She adds that bleach is actually present in our own immune cells, where it helps fight off bacterial infections. If you have a science question, give us a call at 1-800-whyisit. I’m Bob Hirshon, for AAAS, the science society.