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The
Genus Novosphingobium (Sphingomonas) was first described
by Yabuuchi et al. (1990) and later amended by Takeuchi et al. (1993).
Members of this genus belong to the alpha Proteobacterial subdivision and
are characterized as gram-negative, non-spore forming rods displaying a
single polar flagellum when they are motile. They are yellow pigmented
and obligately aerobic. Unlike typical gram-negative bacteria, they do
not have lipopolysaccharide, but rather glycosphingolipid, which is usually
a membrane component of eukaryotic cells. The thermoreversible gel formation
and solution viscosity properties of these glycosphingolipids (sphingans)
make them of technical interest and useful in applications for a wide range
of food and pharmaceutical products (Pollock 1993). An example of its use
is as an agar substitute for growth of thermophiles (marketed as Gelrite).
The role of sphingans has been proposed to be important in colonization
of eukaryotic organisms including plants, marine organisms, and humans
by Novosphingobium. Novosphingobium strains have been
isolated from a wide variety of sources including soil, both marine and
fresh waters, marine life, and from plants. Many of the first isolates
assigned to this genus (S. paucimobilis) were derived from human
clinical specimens or water samples taken from hospital environments and
members of this species have been subsequently shown to behave as opportunistic
pathogens (Miyazaka et. al. 1995). More recently, Novosphingobium has
been linked to the death of coral reefs off the Florida coast (Richardson,
et al. 1998). Although there is an emerging role of Novosphingobium species
in disease, members of this genus are best known for their ability to degrade
a wide variety of aromatic hydrocarbons. |