Health

For the Greater Good: Bacterial Self-Sacrifice

by Jordan Yerman | August 23, 2008 at 07:10 am

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Next time my stomach clenches in agony, I'll spare a thought for the brave, selfless bacteria that gave their own lives so their brethren could colonize my internal organs. I may even have to choke back a tear.

When salmonella enter the digestive tract, they fare poorly: other bacteria have already established their positions. But by sending an advance group digging into intestinal tissues, they set off an inflammatory reaction in their host, sweeping away the other bacteria. The advance group also dies, but the intestine is wide-open for colonization by their brethren.

Since the bugs are genetically identical, the trigger is molecular rather than genetic: about one in six salmonella microbes are randomly "selected" during cell division to go kamikaze. (Were the triggers purely genetic, all the bacteria would sacrifice themselves.) The population flourishes because of the selflessness of a few.

There is a pretty large gap between this and the human or animal version of self-sacrifice, though. An individual bacerium doesn't have rational self-interest in the same way a person does, for example. It isn't choosing between saving the life of its taciturn-yet-inspirational sergeant and coming home to a wife, kids and white picket fence, at least so far as we understand. The phenomenon is no less interesting, though.

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Barry ORegan

flagged this story as Good Stuff

at 11:05 on August 23rd, 2008

jordan, I like this story. It's good stuff. Its good bugs which cured Ulcers, which had plagued many for centuries and only discovered in the last decade or so.