STRUCTURE AND DISTRIBUTION OF GLUCOMANNAN AND SULFATED GLUCAN IN THE CELL WALLS OF THE RED ALGA KAPPAPHYCUS ALVAREZII (GIGARTINALES, RHODOPHYTA)

Abstract

Two new polysaccharides were isolated from the cell walls of the carrageenan producing red seaweed Kappaphycus alvarezii (Doty) Doty. They were characterized by chemical analyses, enzymatic degradations, and nuclear magnetic resonance spectroscopy. One was a 4.0 M NaOH soluble β‐(1,4)‐d‐glucomannan that mostly precipitated upon neutralization and dialysis. It was composed of about 82 residues, and 70% of its glucose and mannose were released by a commercial cellulase enzyme complex. The disaccharide β‐d‐Man (1→4) d‐Glc was recovered from the hydrolysate during the first hours of degradation and confirmed the chemical structure of the polysaccharide. The other polysaccharide was extracted with 1.5 M NaOH and was identified as a sulfated glucan of degree of polymerization of about 180 1,4‐linked β‐glucose containing 10% 1,3‐linkages. The sulfate was located on C‐6 of 64% of the 4‐linked glucose residues. A third alkali‐soluble polysaccharide rich in galactose was also detected. The distribution of the glucomannan and galactose containing polysaccharides was inversely related to the algal cell size. Potential functions of these alkali‐soluble polymers are discussed in the context of cell wall polysaccharide assembly.

Evolution and Diversity of Plant Cell Walls: From Algae to Flowering Plants

“…Because all these taxa, with the exception of the Poales, existed prior to the divergence of Csl [FHJ], this lends support for multiple origins of the polymer (13) but adds uncertainty to elucidating the mechanism by which MLG is synthesized in these groups. The existence of a sulfated MLG in red algae (64) suggests that wall components likely can be modified differentially depending on the presence of co-occurring biosynthetic genes, which may be regulated environmentally (see the section Aquatic Habitats below).…”

Immunolocalization of cell wall carbohydrate epitopes in seaweeds: presence of land plant epitopes in Fucus vesiculosus L. (Phaeophyceae)

“…The composition of algal cell walls differs depending on factors such as species, thallus part, developmental and life-cycle stage, season and habitat (Guibet et al 2008;Kloareg and Quatrano 1988;Kropf et al 1988;Lahaye et al 1994;Lechat et al 2000;Mabeau and Kloareg 1987), further complicating their full characterization. Additionally, many algal cell walls and their components have been characterized after extraction, which allows detailed biochemical characterization.…”

Non-enzymatic isolation of somatic cells fromKappaphycusspp. andEucheuma denticulatum(Solieriaceae, Rhodophyta)

“…NaOH and KOH are used in alkali treatment of crude seaweeds to improve carrageenan quality through modification of carrageenan polymers and dissolution of galactans (Lechat et al, 2000;Therkelsen, 2005), but evidently NaOH and KOH are not useful in inducing tissue dissociation. In tissues treated with carrageenase, softening and disintegration was due to enzymatic hydrolysis, a mechanism described by Mendoza et al (2002) in ice-ice infected K. striatum 'sacol' strain.…”

“…In brown seaweeds for instance, Hasebe (1978) reported that the external application of 1-20% H 2 O 2 only caused stripping off of the 'outer wall and skin' (which we have interpreted to include the cortex). NaOH and KOH on the other hand, are traditionally used in alkali modification of carrageenan to improve the rheological properties of extracted products (Lechat et al, 2000;Therkelsen, 2005).…”