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Applied Microbiology and Biotechnology

, Volume 48, Issue 3, pp 281–288 | Cite as

Bacterial alginates: biosynthesis and applications

  • B. H. A. Rehm
  • S. Valla
MINI-REVIEW

Abstract

Alginate is a copolymer of β-d-mannuronic acid and α-l-guluronic acid (GulA), linked together by 1–4 linkages. The polymer is a well-established industrial product obtained commercially by harvesting brown seaweeds. Some bacteria, mostly derived from the genus Pseudomonas and belonging to the RNA superfamily I, are also capable of producing copious amounts of this polymer as an exopolysaccharide. The molecular genetics, regulation and biochemistry of alginate biosynthesis have been particularly well characterized in the opportunistic human pathogen Pseudomonas aeruginosa, although the biochemistry of the polymerization process is still poorly understood. In the last 3 years major aspects of the molecular genetics of alginate biosynthesis in Azotobacter vinelandii have also been reported. In both organisms the immediate precursor of polymerization is GDP-mannuronic acid, and the sugar residues in this compound are polymerized into mannuronan. This uniform polymer is then further modified by acetylation at positions O-2 and/or O-3 and by epimerization of some of the residues, leading to a variable content of acetyl groups and GulA residues. In contrast, seaweed alginates are not acetylated. The nature of the epimerization steps are more complex in A. vinelandii than in P. aeruginosa, while other aspects of the biochemistry and genetics of alginate biosynthesis appear to be similar. The GulA residue content and distribution strongly affect the physicochemical properties of alginates, and the epimerization process is therefore of great interest from an applied point of view. This article presents a survey of our current knowledge of the molecular genetics and biochemistry of bacterial alginate biosynthesis, as well as of the biotechnological potential of such polymers.

Keywords

Pseudomonas Alginate Pseudomonas Aeruginosa Molecular Genetic Brown Seaweed 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • B. H. A. Rehm
    • 1
  • S. Valla
    • 2
  1. 1.Institut für Mikrobiologie der Westfälischen Wilhelms-Universität Münster, Corrensstr. 3, D-48149 Münster, Germany Tel.: +49 251 833 9848 Fax: +49 251 833 8388 e-mail: Rehm@uni-muenster.deDE
  2. 2.UNIGEN, Center for Molecular Biology, Norwegian University of Science and Technology, 7005 Trondheim, NorwayNO

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