The Actinomycetales is an order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally gram-positive and anaerobic and have mycelia in a filamentous and branching growth pattern. Some actinomycetes can form rod- or coccoid-shaped forms, while others can form spores on aerial . Actinomycetales bacteria can be infected by , which are called actinophages. Actinomycetales can range from harmless bacteria to pathogens with resistance to antibiotics.
Reproduction
Actinomycetales have 2 main forms of reproduction:
spore formation and hyphae fragmentation. During reproduction, Actinomycetales can form
conidiophores, sporangiospores, and oidiospores. In reproducing through hyphae fragmentation, the hyphae formed by Actinomycetales can be a fifth to half the size of fungal hyphae, and bear long spore chains.
Presence and associations
Actinomycetales can be found mostly in soil and decaying organic matter, as well as in living organisms such as humans and animals. They form symbiotic
nitrogen fixing associations with over 200 species of plants, and can also serve as growth promoting or biocontrol agents, or cause disease in some species of plants. Actinomycetales can be found in the human
urogenital tract as well as in the
digestive system including the mouth, throat, and
gastrointestinal tract in the form of Helicobacter without causing disease in the host. They also have wide medicinal and
botanical applications, and are used as a source of many
antibiotics and
pesticides.
Antimicrobial properties
Many species of Actinomycetes produce antimicrobial compounds under certain conditions and growth media.
Streptomycin,
actinomycin, and
streptothricin are all medically important antibiotics isolated from Actinomycetes bacteria.
Almost two-thirds of the natural antimicrobial drug compounds used currently are produced by different species of Actinomycetes.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)
and National Center for Biotechnology Information (NCBI).
See also
-
Bacterial taxonomy
-
List of bacterial orders
-
List of bacteria genera
