Occurrence, production, and applications of gellan: current state and perspectives.
Bacterial exopolysaccharides (EPS) are products of biotechnology that are of high interest due to their rheological properties. This is the case of sphingans, a group of structurally related EPS secreted by members of the genus Sphingomonas. Among these, gellan is a multifunctional gelling agent produced in high yields by the non-pathogenic strain Sphingomonas elodea ATCC 31461. In its native form, gellan is a linear anionic EPS based on a tetrasaccharide repeat unit composed of two molecules of D: -glucose, one of L: -rhamnose and one of D: -glucuronic acid. The native gellan is partially esterified with acyl substituents (1 mol of glycerate and 0.5 mol of acetate) per repeat unit. Gellan has unique characteristics and has many applications, particularly in the food, pharmaceutical, and biomedical fields. This review summarizes current knowledge on the structure and properties of gellan and provides details about the biosynthesis of this exopolysaccharide. In addition, a highlight of the importance of gellan in industrial and medicinal applications is given.
Fialho
Arsenio M
AM
IBB-Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal. afialho@ist.utl.pt
Moreira
Leonilde M
LM
Granja
Ana Teresa
AT
Popescu
Alma O
AO
Hoffmann
Karen
K
Sá-Correia
Isabel
I
D001704:Biopolymers / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D053898:Biosynthetic Pathways; D005285:Fermentation; D005818:Genetic Engineering; D016680:Genome, Bacterial; D007218:Industrial Microbiology; D010802:Phylogeny; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D020578:Sphingomonas / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*
D001704:Biopolymers; D011135:Polysaccharides, Bacterial; C048288:gellan gum