Planktonic/sessile dimorphism of polysaccharide-encapsulated sphingomonads.

Sphingomonads have acquired diverse metabolic activities to inhabit a wide range of environments. Several strains of Sphingomonas display phenotypic dimorphism and can adopt either a planktonic or sessile behavior in liquid media. The sessile state is marked by the presence of a viscous exopolysaccharide capsule. Specific types of these capsular polysaccharides are harvested from large-scale fermentations for use as rheology modifiers in many industrial and food applications. Sensing of environmental stimuli and genetic control over synthesis of the capsule are key events in alternating between these two phenotypes.