Observing fungi in a Petri dish
Students should examine cultures in containers, which have been taped and closed. Colony morphology is a method that scientists use to describe the characteristics of an individual colony of fungi growing on agar in a Petri dish. It can be used to help to identify them.
Different types of fungi will produce different-looking colonies, some colonies may be coloured, some colonies are circular in shape, and others are irregular. A specific terminology is used to describe common colony types. These are:
- Form – what is the basic shape of the colony? For example, circular, filamentous, etc.
- Size – the diameter of the colony. Tiny colonies are referred to as punctiform
- Elevation – this describes the side view of a colony. Turn the Petri dish on end.
- Margin/border – the edge of a colony. What is the magnified shape of the edge of the colony?
- Surface – how does the surface of the colony appear? For example, smooth, glistening, rough, wrinkled, or dull.
- Opacity – for example, transparent (clear), opaque, translucent (like looking through frosted glass), etc.
- Colour (pigmentation) – for example, white, buff, red, purple, etc.
Yeast colonies are very similar to bacterial colonies.
Moulds often have fuzzy edges. They usually turn into a different colour, from the centre outwards.PDF download - Colony Morphology