Dimorphic prosthecate bacteria (DPB) are alpha-proteobacteria that reproduce in an asymmetric manner rather than by binary fission and are of interest as simple models of development. In these non-budding, aquatic prosthecate bacteria, reproduction results in two cells that are morphologically and behaviourally different from each other. One is non-motile, sessile by virtue of adhesive material and prosthecate, possessing at least one elongated, cylindrical appendage (a prostheca) that is an outgrowth of the cell envelope, including the outer membrane, the peptidoglycan layer and the cell membrane. The other is flagellated, bearing one polar flagellum, by which it is motile. The stalks synthesized by some Alphaproteobacteria take up diffuse compounds from water sources, a feature that could be exploited for bioremediation, specifically the uptake of toxic compounds from contaminated water sources. Furthermore, extracellular polysaccharides from some of the stalked bacteria sequester metals, a feature that could be used to remediate environments affected by metal toxicity.

Asticcacaulis excentricus are colorless thick rods whose stalks do not possess adhesive material and are invariably excentral (the stalk is not centered). They require biotin for growth. Strain CB 48, initially designated AC48, is the type strain. It was isolated from pond water in North Carolina USA in October 1962 (adapted from mmbr.asm.org/content/28/3/231.citation).