Uses of good microbes

1. Yoghurt
Special types of bacteria called lactobacillus can
convert milk into yoghurt. They can also turn milk
into cheese.
An enzyme in the bacteria reacts with sugar in
the milk (called lactose) and converts
it into lactic acid. Lactic acid
changes milk proteins and forms
the thicker yoghurt.

2. Cheese
Cheese is made by adding an enzyme called rennet
after bacteria have produced lactic acid in milk.
Rennet makes milk proteins turn solid and this is
the basis for cheese.
Blue cheese is blue because it is mouldy!
Types of fungi are added into the cheese
to make the blue veins.

3. Brewing- wine and
beer
Beer and wine are made using yeast. Yeast is a type of fungi
that contains an enzyme which will convert sugar (Glucose)
and water into carbon dioxide and alcohol (ethanol) .
In this process there is no oxygen, therefore yeast uses
anaerobic respiration, this is known as fermentation which is
used to make alcoholic drinks.
In some countries like Brazil alcohol is made
from sugar cane and can be used instead of petrol
in cars!

4. Vinegar
Another food product that is made by
microbes is vinegar. Certain bacteria
can turn alcohol into an acid called
acetic acid (the scientific name for
vinegar). Bacteria can turn all types of
alcohol into vinegar including wine,
beer and cider.
Extra challenge question:
What is the pH of acids?

5. Bread
Bread dough contains flour, water, sugar and yeast. The sugar
allows the yeast to grow, respire and reproduce.
The dough is stretch and folded (kneaded) to trap air in it so
that the yeast have enough oxygen for aerobic respiration.
The carbon dioxide produced causes the bread to rise
and fills the bread full of bubbles.
The alcohol evaporates during
the baking process.

6. A type of fungi is used to make Quorn. The fungi are
grown in large chambers; collected and compressed
together to form the blocks of Quorn.
Quorn is a healthy alternative to meat because it is
high in protein but low in fat, and as it is made from
microbes, not animals, it is suitable for vegetarians.