Sphingomonas

Sphingomonas was defined in 1990 as a group of Gram-negative, rod-shaped, chemoheterotrophic, strictly aerobic bacteria. They possess ubiquinone 10 as their major respiratory quinone, contain glycosphingolipids (GSLs), specifically ceramide, instead of lipopolysaccharide (LPS) in their cell envelopes, and typically produce yellow-pigmented colonies. The GSL serves to protect the bacteria from antibacterial substances. Unlike most Gram-negative bacteria, Sphingomonas cannot carry endotoxins due to the lack of lipopolysaccharides, and has a hydrophobic surface characterized by the short nature of the GSL's carbohydrate portion.

By 2001, the genus included more than 20 species that were quite diverse in terms of their phylogenetic, ecological, and physiological properties. As a result, Sphingomonas was subdivided into different genera: Sphingomonas, Sphingobium, Novosphingobium, Sphingosinicella, and Sphingopyxis. These genera are commonly referred to collectively as sphingomonads. Distinct from other sphingomonads, Sphingomonas genomic structure includes a unique lipid formation, major 2-OH fatty acids, homospermidine as the primary polyamine, and signature nucleotide bases within the 16S rRNA gene. The bacteria holds 3914 proteins, 70 organizational RNA, and 3,948,000 base pairs (incomplete observation).