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This is a tale of tails. The moral of the tale: Science isn't just about combing the textbooks for the answers to tomorrow’s quiz. Sometimes science changes what textbooks
say! We’re not suggesting you mark up your school books with red ink. But sometimes we discover that the scientists before us were wrong. Consider the case of microbiologist Peter Holt. For 60 years, the textbooks have had it wrong about a microscopic critter called Salmonella pullorum [sal-mun-EL-uh pull-OR-um). The books said this germ DOESN'T have whip-like tails called flagella [fluh-JELL-uh]. Oh yes they do, Holt discovered. They use them, like tiny oars, to wiggle through the bloodstream of chickens. Holt works at the Southeast Poultry Research Laboratory in Athens, Ga. It's part of the USDA's Agricultural Research Service. Some types of Salmonella he studies can make people sick. And some types, including Pullorum, cost farmers money--by killing their chickens. Finding flagella is good because it makes bacteria easier to detect in a sample of a chicken's blood. Why? Because, cells called antibodies that attack germs REALLY gang up on those tails. And this helps scientists make test kits to find out which Salmonella, if any, are present. Trouble was, most Salmonella that have flagella have relatively thick, stubby ones. Holt proved pullorum is different: it has fine, feathery, hairlike flagella that were kind of finicky about growing out. How did Holt get the heads-up on pullorum's tails? He borrowed a special growth medium from other scientists.
Holt used a special microscope and camera to be sure he was right about the tails. The pictures show why the tails were hard to find. As you can see, most Salmonella strains have thick, not feathery, flagella. Now that Dr. Holt has caught pullorum by its tail, a company can make test kits to detect the germ faster. If they do, it will help birds, farmers and anyone who likes fried chicken. —By Jill Lee, formerly, Agricultural Research Service, Information Staff Want to learn more? Check out these
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A growth medium is a
chemical "soup"--a mix of proteins, hormones and other goodies. Some of them
are made so that bacteria will do things they don’t do in a normal lab
sample. Bacteria like pullorum act differently based on where they
are--just like you probably act differently at home than at school. In this
case, the medium made pullorum feel like sprouting some tails and going
mobile. 