Relatively large, motile filaments (100-500 µm). Straight filaments with no branching. Cells are rectangular (1-3 x 4-8 µm). Filaments are found free in the bulk solution and are motile with a gliding and flexing movement. The filament staining is Gram negative but may stain Gram positive if sulfur is present and Neisser negative with Neisser positive granules observed frequently. Usually easy to identify due to its gliding motion. Contains substantial refractile spherical sulfur granules and the cell septa is not visible when sulfur is present. No Sheath. No attached growth.

This is the only actively motile filamentous bacteria with gliding and flexing action.

This filament is usually found in environments where there are septic wastes and sulfides. It is commonly observed in activated sludge but rarely causes bulking, if it does it is usually inter-floc bridging. Beggiatoa is found in RBC units and trickling filters and can cause clogging of filters and growth overloading on RBC units that can lead to shaft failures.

Septic wastes can be altered by pre-aeration or pre-chlorination.

Beggiatoa ranks 16th in number of predominance.