Angie Matinucci, age 10, of St. Paul, Minnesota, for her question:

How do they make penicillin?

This wonder drug is created by living, microscopic molds. It was discovered accidentally in 1928. A colony of penicillium molds produced a germicide that destroyed surrounding germs. The little wonder workers were pampered and coddled in special broths to produce more of the miraculous medicine. Researchers found better strains of the mold that produced bigger and better doses. Later, scientists learned how to make penicillin from simple chemicals. But the process was expensive and the little molds were very happy to do the job for much less.

Nowadays, penicillin is made in huge tanks that hold perhaps 10,000 gallons. The culture is a rich broth of suitable nutrients, kept at the right temperature. A colony of the penicillium molds is added and the soupy fluid is kept stirred by a stream of air. They thrive, multiply and produce their wonder drug. When the job is done, fine sieves are used to remove the molds and other impurities. The liquid is purified again, then dried to form powdered penicillin.