Studies on exopolysaccharide release by diazotrophic batch cultures of Cyanospira capsulata

Abstract

Diazotrophic batch cultures of Cyanospira capsulata producing large amounts of a soluble exopolysaccharide (EPS) were studied over a period of about 30 days under continuous illumination. The thickness of the capsule surrounding the trichomes remained almost the same throughout the growth phases and the EPS was continuously released into the medium at a rate which was roughly constant throughout the culture period. A mean EPS productivity of about 6 g m -2 day-1 was attained. Purified EPS samples exhibited a saccharidic composition consisting of four neutral sugars (glucose, mannose, fucose and arabinose) and galacturonic acid in a molar ratio of 1 : 1 : 1 : 1 : 2, respectively. The EPS was also characterized by the presence of pyruvic residues and by a protein content of about 2%. O-Acetyl groups and sulphate residues were not detected. The massive release of this polysaccharidic material into the liquid medium made the cultures progressively more viscous.

Characterization of Glycoconjugates of Extracellular Polymeric Substances in Tufa-Associated Biofilms by Using Fluorescence Lectin-Binding Analysis

“…rubrum and in both fractions of Chroococcus submarinus. Molar ratios of monosaccharides were similar between capsular and released polysaccharides for 4 out of 6 strains, which supported the hypothesis that released polysaccharides are a fraction of capsular polysaccharides (16,32,61). Capsular polysaccharides are linked to the cell surface of a bacterium via covalent attachments to either phospholipids or lipid A molecules (63).…”

Characterization of exopolysaccharides produced by seven biofilm-forming cyanobacterial strains for biotechnological applications

“…It is known that higher temperature and light intensities favor the increase of EPS production (Di ). This has been previously reported on EPS production by diatoms (Staats et al 2000;Wolfstein and Stal 2002) and cyanobacteria (Vincenzini et al 1990;Moreno et al 1998;Otero and Vincenzini 2003) demonstrating a clear and direct relationship between the production of EPS and oxygenic photosynthesis; it would therefore be quite reasonable to expect increasing EPS production with an increase in temperature and light. It is possible that the biofilm thickness and its multi-stratified structure caused strong attenuation of light in the upper biofilm layers.…”

Cyanobacterial defense mechanisms against foreign DNA transfer and their impact on genetic engineering

“…Several unicellular subsection I cyanobacteria are described as sheathless (Rippka et al, 1979), but that does not imply that there is no EPS production in those strains, as polysaccharides can be also released into the extracellular matrix. Synechocystis produces 30 mg L -1 of RPS in 30 days (Panoff et al, 1988), and S. elongatus PCC 7942 can produce up to 462 mg L -1 in 21 days (Sangar and Dugan 1972), values that are similar to other unicellular cyanobacteria (De Philippis and Vincenzini 1998) and comparably lower than the RPS production of Cyanospira capsulata, which can reach 4 g L -1 in 31 days (Vincenzini et al, 1990). Cyanobacteria that are diffi cult to transform such as Fischerella muscicola and Chlorogloeopsis fritschii, produce large amounts of CPS corresponding to 15-30% of the total cell dry mass (Schader et al, 1982, Pritzer et al, 1989.…”