Yield, chemical composition and gel strength of agarocolloids of Gracilaria gracilis, Gracilariopsis longissima and the newly reported Gracilaria cf. vermiculophylla from Roscoff (Brittany, France) |
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Authors: | Jean-Claude Mollet Abdeslem Rahaoui Yves Lemoine |
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Institution: | (1) Laboratoire de Cytophysiologie végétale et de Phycologie, Université des Sciences et Technologies de Lille, UFR de Biologie Bat, SN2 Cité Scientifique, 59655 Villeneuve d'Ascq cedex, France |
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Abstract: | Agarocolloids were extracted from field samples of Gracilaria gracilis, Gracilariopsis longissima and the newly reported Gracilaria
cf. vermiculophylla harvested at different periods of the year near Roscoff (France). Native and alkali modified extracts
were characterized by GLC, HPLC and FT-IR spectroscopy. The main components of agarocolloids isolated by freeze-thawing method,
were 3,6-anhydrogalactose and galactose. In addition, minor components (6-O-methyl-galactose, 4-O-methyl-galactose and sulfate
groups ranging from 4.4 up to 6.6% w/w]) were detected. The highest rate of 6-O-methylgalactose was observed in agarocolloids
from vermiculophylla (14 mole%). Sulfates were mainly branched on C4 of the D-galactose in gracilis and Gs. longissima agarocolloids.
G. vermiculophylla agaroids isolated by EtOH and NaCl precipitations from the syneresis water were characterized by a high
sulfation on C6 of galactose and a low sulfation on C2 of 3,6-anhydrogalactose. Native agarocolloid gel strengths from Gracilaria
species were clearly higher than those of Gracilariopsis. Alkali treatments reduced the sulfate levels but increased slightly
the gel strengths. An approximation of the polymer sizes carried out with colorimetric assays indicated that the polymer sizes
were higher in G. gracilis than observed in Gs. longissima.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | agarocolloid extracellular matrix cell wall galactans Gracilaria gracilis Gracilaria cf vermiculophylla Gracilariopsis longissima Rhodophyta |
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