Can microorganisms blow up balloons?

What you need:

Three small balloons, three packets of yeast, sugar, warm water, three one-litre plastic bottles

What to do:

  • Fill up each bottle with about one inch of very warm water.
  • Put one packet of yeast into each bottle.
  • Now, in the first bottle, put one teaspoon of sugar; in the second one, put two teaspoons, and three teaspoons in the third. Cap all the bottles and shake them well.
  • Open the caps and put the three balloons on the bottles' necks. Leave the bottles undisturbed for a couple of hours.

 What happens:

The balloons begin to inflate in a while. The bottle with the maximum amount of sugar has the most inflated balloon.


Yeasts are nothing but a kind of microorganism. They like to feed on sugar. Which is why they are used mostly in baking.

Yeasts require warmth and moisture to become active.

When yeasts begin to feed on sugar, carbon dioxide gas is released. This gas fills the bottle and then inflates the balloon. The more sugar the yeasts get to eat, the more gas they release and the more the balloon inflates.

Picture Credit : Google

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