Wednesday, July 7, 2010


PURPOSE : To determine the best way to grow penicillin.

MATERIALS : Cotton balls
                           2 oranges
                           2 lemons
                           2 bread sacks

  • Rub the fruit on the floor.
  • Place the fruit in a bowl exposed to the air for one day.
  • Place in each bread sack an orange, a lemon, and a cotton ball wet with water.
  • Secure the ends of the sacks.
  • Place one sack in the refrigerator and the other in a warm dark place.
  • Leave the sacks closed for two weeks.
  • Observe the fruit through the sacks daily.
RESULTS : The fruit in the refrigerator looks the same or possibly a bit dryer, but the other fruit has turned into blue green fuzzy balls.

WHY ? The green powder growth on the outside of the fruit is penicillius. Under a microscope this mold looks like a small brush thus it was named from the latin word penicillus meaning a paint brush. Because brushes were used to write with at one time, our modern writing tool, the pencil, is named after the latin word for paintbrush. Molds can grow in hot places, but they grow faster and in more abundance in moist warm places. This is why foods become more moidy in the summertime. Placing bread in a bread box or on top of a refrigerator causes them to mold more quickly. Cooling foods slows down the growth of mold and freezing keeps foods fresh for much longer periods of time. 

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