group of oil bacteria resembling fungi . Actinomycetes play a role in the decomposition of organic matter and the release of mineral elements.
|Scanning electron micrograph of Actinomyces israelii.|
The Actinomycetales are an order of Actinobacteria. A member of the order is often called an actinomycete. The actinomycetes are very diverse and contain a variety of subdivisions, as well as yet-unclassified isolates, mainly because some genera are very difficult to classify because of a highly niche-dependent phenotype. For example, Nocardia contains several phenotypes first believed to be distinct species before their differences were shown to be entirely dependent on their growth conditions.
Actinomycetales are generally gram-positive and anaerobic and have mycelium in a filamentous and branching growth pattern. Some actinobacteria can form rod- or coccoid-shaped forms, while others can form spores on aerial hyphae.
Actinomycetales bacteria can be infected by bacteriophages, which are called actinophages.
Actinomycetales can range from harmless bacteria to pathogens with resistance to antibiotics.