Question

How do fungal colonies differ from bacterial colonies? And why are Actinomyces bacteria not classified as fungi?

Answer 1

Answer:

1st part:

The fungal colonies differ from bacterial colonies as:

The fungal colonies are:

1. Larger colonies
2. They have a powder-like (i.e, fuzzy) appearance
3. They grow within the pH 5-6
4. They are filamentous or rhizoid morphologically.
5. They have a filamentous margin.

Whereas the bacterial colonies are:

1. Smaller colonies.
2. They have a rough or smoother appearance.
3. They grow within the pH 5-9 (optimum 7).
4. They are colonies are circular or irregular morphologically.
5. They have a defined margin.

2nd part:

Earlier Actinomyces was classified as fungi due to its mycelial structure and the formation of structures like conidia on the aerial branches (character of a filamentous fungus). But later they were grouped as prokaryotic bacteria as they more closely represented bacteria in the cell wall structure and its chemical composition. They are Gram-positive bacteria.

A popular Actinomyces is Streptomycetes which is used in the production of several antibiotics such as streptomycin, erythromycin.

Therefore, today they are classified as a gram-positive prokaryotic bacteria with a filamentous structure and not as fungi.