Actinomycetes are huge group of primarily filamentous soil bacteria. Cells of actinomycetes lack a nucleus or nuclear membrane, in contrast to the fungal cells where the nucleus is present. Instead, cells of actinomycetes, like other prokaryotes, possess a single chromosome composed solely of DNA. Cells of actinomycetes form filaments that thinner than fungal hyphae. Also actinomycetes form radial fungi-like colonies on agar plates, but they are smaller than fungal colonies. Both fungi and actinomycetes produce spores. These two groups of microorganisms have the same ecological function – decomposers.