Agars from Three Fijian Gracilaria Species
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R. Falshaw
Abstract
The polysaccharides present in three species of Gracilaria from a single site in Fiji, G. maramae South, G. edulis (Gmelin) Silva and G. arcuata Zanardini v. snackeyi Weber van Bosse have been characterised as substituted agars by chemical, physical and 13C-NMR spectroscopic analyses, primarily after alkali treatment. The agar from Gracilaria edulis is unmethylated but 13% of the 3-linked β-D-galactopyranosyl units bear 4,6-O-pyruvate acetal substituents. The resonance for the quaternary carbon of the pyruvate acetal was observed in the 13C-NMR spectrum of this agar. The agar from Gracilaria maramae is partially methylated, 45% on O-6 of the 3-linked β-D-galactopyranosyl units and 10% on O-2 of the 4-linked 3,6-anhydro-α-L-galactopyranosyl units. In addition, constituent sugar and glycosyl linkage analyses revealed 7 mol% of 4-linked L-galactopyranosyl units not clearly observed by 13C-NMR spectroscopy. The agar from Gracilaria arcuata v. snackeyi is much more highly methylated, 83% on O-6 of the β-D-galactopyranosyl and 88% on O-2 of the 3,6-anhydro-α-L-galactopyranosyl units. The alkali-modified agars were obtained in acceptable yields and their gels had good clarity and low colour but gel strengths (300–350 g cm−2 for 1% gels) at the low end of the range favoured by agar processors. The Gracilaria arcuata v. snackeyi agar has a higher melting point (ca. 100 °C) than conventional agars, which may be a useful new property.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Studies on the Fatty Acids of the Red Alga Chondria armata (Kütz.) Okamura
- First Report of the Genus Sorocarpus Pringsheim (Fucophyceae, Ectocarpaceae) in the Mediterranean
- Light-Induced Photoinhibitory Stress Reponses of Laboratory-Cultured Halophila ovalis
- Factorial Study of the Effects of Phosphorus and Nitrogen Enrichments on Nutrient and Carrageenan Content in Chondrus crispus (Rhodophyceae) and on Residual Nutrient Concentration in Seawater
- First Record of Haloguignardia cystoseira (Ascomycota) Parasitic on Cystoseira elegans (Fucophyceae) from the Mediterranean Sea
- Pseudogrinnellia barrattiae gen. et sp. nov., a New Member of the Red Algal Family Delesseriacea from the Sultanate of Oman
- Seasonal Dynamics of Growth in the Barents Sea Seaweeds: Endogenous and Exogenous Regulation
- Agars from Three Fijian Gracilaria Species
- New Collections of Benthic Marine Algae from Livingston and Deception Islands (South Shetland Islands) and Trinity Island (Bransfield Strait) Antarctica
- The Introduced Alga Undaria pinnatifida (Laminariales, Alariaceae) in the Rocky Shore Ecosystem of the St Malo Area: Morphology and Growth of the Sporophyte
- The Introduced Alga Undaria pinnatifida (Laminariales, Alariaceae) in the Rocky Shore Ecosystem of the St Malo Area: Growth Rate and Longevity of the Sporophyte
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