Chlamydobacteriales

(iron bacteria), an order of filamentous bacteria up to 1 cm in length that are divided by septa into cylindrical cells, each of which measures 0.5–2μ by 2–5μ. Chlamydobacteria, which are nonpathogenic aerobic heterotrophs, do not form endospores. They live in freshwaters and can be grown on various nutrient media.

Certain chlamydobacteria, for example Sphaerotilus natans, form visible whitish tassels in bodies of water. Groups of chlamydobacteria are enclosed in a sheath formed from a mucous membrane. In Leptothrix ochracea the sheath is rust-colored as a result of being impregnated with iron hydroxide.

Chlamydobacteria can reproduce either by the detachment of individual nonmotile cells as a result of the development of transverse septa in the filament or by motile swarmers, which appear at the end of the filament and are able to swim with the aid of flagella. Both the nonmotile cells and the swarmers grow to give rise to new filaments, which can either be free-floating or fixed to a solid substrate. False branching is observed in many chlamydobacteria.