Exploitation of the metabolic capabilities of the genus Sphingomonas could provide important commercial benefits to biotechnology. Recent advances have demonstrated that these organisms have unique abilities to degrade refractory contaminants, to serve as bacterial antagonists to phytopathogenic fungi, and to secrete the highly useful gellan exopolysaccharides. Unfortunately, Sphingomonas are also animal pathogens and can readily degrade the copper pipes in drinking water distribution systems. The closely related Zymomonas could be important for commercial ethanol production. These Gram-negative aerobic bacteria are characterized by an outer membrane that contains glycosphingolipids, but lacks lipopolysaccharide. Their distribution in environmental samples has not been systematically examined as yet.