Extracellular carbohydrate polymers from five desert soil algae with different cohesion in the stabilization of fine sand grain

Macromolecular and chemical features of the excreted extracellular polysaccharides in induced biological soil crusts of different ages

“…In this connection, it has to be stressed that the monosaccharidic composition of the EPSs extracted from IBSCs in the experimental sites under study was found to be very complex, being these macromolecules characterized by the presence of a large number of different types of sugars, in spite of the limiting conditions faced by cyanobacteria in natural arid environments (Brüll et al, 2000). The high number of different types of monosaccharides and the significant presence of rhamnose and uronic acids, which is a typical feature of cyanobacterial EPSs (De Philippis et al, 2001;Hu et al, 2003;Pereira et al, 2009;Xu et al, 2012), suggest a predominant role of cyanobacteria in the excretion of these macromolecules in the IBSCs studied. The overall level of complexity of the secreted molecules can be considered as an indicator of the good capability of the inoculated cyanobacteria to adapt to the environmental conditions.…”

A physico-chemical comparative study on extracellular carbohydrate polymers from five desert algae

“…The large values for the frictional ratio could be due either to a large degree of swelling through water association or 'hydration' of the polysaccharides, or due to strong departure from spherical or coiled asymmetry, or perhaps a combination of both. It is impossible to distinguish the two on the basis of ultracentrifuge measurements alone, but the data are at least consistent with a stiffish random coil conformation as mentioned above in relation to the MHKS data, which is also consistent with the chemical composition of these polymers which do not appear to have significant amounts of charged residues (Hu et al, 2003).…”

“…Nostoc sp., M. vaginatus, D. olivaceus, P. tenue and S. javanicum previously fractionated by anion exchange column chromatography was supplied by Hu et al (2003).…”

“…A physico-chemical investigation would appear to provide underpinning information concerning the function and uses of these materials. The algal exopolysaccharides investigated in this article were obtained from the media cultures of Nostoc sp., Microcoleus vaginatus, Desmococcus olivaceus, Phormidium tenue and Scystonema javanicum which have been separated from desert algal crusts of the Tegger Desert of China as described in Hu, Paulsen, Petersen, and Klaveness (2003).…”

“…The aim of the study was to further purify the algal exopolysaccharides from 1 M NaCl fractions previously fractionated by Hu et al (2003) and determine the composition, hydrodynamic properties (namely molecular weight and sedimentation velocity coefficients) of the purified carbohydrate polymers. These techniques have the advantages of requiring only small amounts of purified material.…”