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Culture
medium
Bacteria,
fungi, and plant and animal cells are grown on nutrient material
called culture media. To grow a particular cell, the medium must
contain the right nutrients for that cell. It should also contain
sufficient water and oxygen, and an appropriate pH. The cells
that grow in or on the culture medium are referred to as a
culture.
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Some
culture media are liquids or broths.
When
it is desirable to have a solid surface, agar is added to
the liquid nutrients. Agar
is a complex polysaccharide derived from a marine alga.
Agar has a long history as a thickener in foods such as
soups and ice cream. In fact, agar was first introduced
into culture media by Angelina Hess when she realized the
need for a solid medium could be met from her own kitchen.The
agar is not digested by the cells being grown so the medium
remains solid.
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media in these three tubes contain the same growth nutrients.
1.5% agar has been added to tubes B and C so they are solid. |
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