Page 22 - Innovator's Science-8

Microorganisms like bacteria and fungi help solve many environmental
issues by breaking down harmful substances, cleaning polluted water and

soil, and even reducing greenhouse gases that cause climate change. They
can also help recycle nutrients, promote plant growth, and clean up waste
products. So, microorganisms are very useful in protecting and improving
our environment in many ways.

Just as microorganisms help the environment, they also play an important
role in food preparation.

MICROORGANISMS AND FOOD
Let us try to understand by performing activities in the kitchen.

Take two bowls labelled A and B. In each bowl, put 200 grams of flour
(either atta or maida) and add a pinch of sugar. In bowl A, add a small
amount of yeast powder and mix it well with the flour. In bowl B, do not add

any yeast so you can compare what happens in both bowls. Then, in each
bowl, add warm water and knead the flour to make soft dough. The yeast is
a tiny living organism that feeds on sugar and produces gases, especially

carbon dioxide, through a process called fermentation. This gas helps the
dough in bowl A to rise and become soft and fluffy when baked. In bowl B,
without yeast, the dough won't rise because there is no fermentation
happening. Now cover the dough with a damp cloth and keep it in a warm
place. Observe both the bowls after 4–5 hours.
a. Dough in bowl A
When you observe the dough after some time, you may notice that the
dough in bowl A (with yeast) has risen, become fluffy, and has a different

smell compared to the dough in bowl B (without yeast). This happens
because yeast is a type of microorganism that belongs to the fungi group.
Yeast grows best in warm conditions and during its growth; it breaks down
sugar through respiration to release energy. While doing this, yeast
b. Dough in bowl B
Change in the volume produces carbon dioxide gas, which gets trapped in the dough as bubbles,
of flour after addition making the dough rise and become soft and fluffy. Yeast also produces a
of yeast, sugar, and
warm water small amount of alcohol, which gives the dough a special smell. This
process is called fermentation and is used in making bread, cakes, and

other baked goods. Besides yeast, some bacteria like Lactobacillus also
help in fermenting batter and dough for foods like idli, dosa, and bhatura.

AMAZING MICROALGAE: TINY HELPERS IN WATER

Microalgae are microscopic plant-like organisms that live in water, soil, air,
and even on trees. They make their own food using sunlight. While doing

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Science-8