Complexity of cyanobacterial exopolysaccharides: composition, structures, inducing factors and putative genes involved in their biosynthesis and assembly

• Published in: FEMS microbiology reviews 2009-09, Vol.33 (5), p.917-941
• Main Authors: Pereira, Sara, Zille, Andrea, Micheletti, Ernesto, Moradas-Ferreira, Pedro, De Philippis, Roberto, Tamagnini, Paula
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Biosynthesis; Complexity; Composition; Cyanobacteria; Cyanobacteria - genetics; Cyanobacteria - metabolism; Environmental conditions; Exopolysaccharides; extracellular polymeric substance biosynthesis; extracellular polymeric substances; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Gene sequencing; Genes; Genomes; Microbiology; Miscellaneous; Polysaccharides, Bacterial - biosynthesis; Polysaccharides, Bacterial - chemistry; Polysaccharides, Bacterial - metabolism; released polysaccharides
• ISSN: 0168-6445; 1574-6976; 1574-6976
• DOI: 10.1111/j.1574-6976.2009.00183.x

Cyanobacterial extracellular polymeric substances (EPS) are mainly composed of high-molecular-mass heteropolysaccharides, with variable composition and roles according to the microorganism and the environmental conditions. The number of constituents - both saccharidic and nonsaccharidic - and the complexity of structures give rise to speculations on how intricate their biosynthetic pathways could be, and how many genes may be involved in their production. However, little is known regarding the cyanobacterial EPS biosynthetic pathways and regulating factors. This review organizes available information on cyanobacterial EPS, including their composition, function and factors affecting their synthesis, and from the in silico analysis of available cyanobacterial genome sequences, proposes a putative mechanism for their biosynthesis.