Low-molecular-rsnass carbohydrates and soluble polysaccharides of green and red morphs of Gracilaria domingensis (Gracilariales, Rhodophyta)

摘要

We studied the chemical structure and yield of low-molecular-mass carbohydrates (LMMC) and soluble polysaccharides produced by green and red morphs of Gracilaria domingensis. Red plants had higher amounts of the LMMC floridoside than green morphs (324.4+8.1 and 220.1+6.0 mu mol g~(-1) dry biomass, respectively). The yield of polysaccharides was similar between morphs (46.3±5.8% for the red and 41.4+8.3% for the green) as was the monosaccharide composition. The same agaran (6-O-methylated and sulphated) was isolated from both morphs, as determined by ~(13)C NMR spectroscopy analysis. The floridean starch content (mg g~(-1) dry biomass) for the green morphs (116.2+1.7) was lower than that of the red morphs (143.9±1.8). This study showed that green and red morphs of G. domingensis are similar in their polysaccharide composition, but differ in the short-term storage compounds, starch and floridoside. These differences may be related to light and shade photo-synthetic strategies, which lead to different storage accumulation.