ctinomycetes usually have 1-2 µm diameter.

They generally possess a rod shape with a filamentous or branched structure. The filaments contain mumaric acid.

Most of the species are aerobic, while a few are anaerobes to facultative aerobes.

Cell wall and internal structures are similar to bacteria. The cell wall of actinomycetes consists of mycolic acid.

The growth or reproduction of actinomycetes is slower than the bacteria and fungi. Hence, actinomycetes are sometimes called as “Slow growers”.

They are having 60-78% of G+C content.

Actinomycetes are most abundant in soil (106-108g) and marine habitat.

The majority of species are usually non-motile, non-capsulated and non-acid fast.

They show optimum growth at alkaline pH.