Colorimetric Estimation of Acidic Polysaccharide Content of Gymnodinium Breve

Abstract

A colorimetric method for estimating acidic polysaccharide content of planktonic cells has been adapted. The method depends upon the spectral shift induced when polysaccharides are added to an aqueous dioxane solution of carbocyanine dye. The polysaccharide content was expressed as heparin equivalents, i.e., μg per million cells. For sodium heparin, the calibration relationship was: A₆₀₀ = 0.043 μg heparin equivalent. The error in the calibration relationship is small (the standard deviation of the slope is 0.003). The method was applied to the acidic polysaccharide content of the Florida red tide organism, Gymnodinium breve. The content was higher (ave., 23.5 μg/million cells) for cells in log growth phase for lower salinities (26–34 ‰) than for higher salinities (36, 38 ‰).

Key Words:

• Gymnodinium breve
• red tide
• acidic polysaccharide
• colorimetric analysis
• heparin
• carbocyanine dye