A simple combined method for determination of β-1,3-glucan and cell wall polysaccharides in diatoms

A new method is described for the combined determination of beta-1,3-glucan and cell wall polysaccharides in diatoms, representing total cellular carbohydrate. The glucan is extracted by 0.05 mol l(-1) H2SO4 at 60 degreesC for 10 min, and the cell wall polysaccharides are subsequently hydrolyzed by 80% H2SO4 at 0-4 degreesC for 20 h. Each carbohydrate fraction is determined by the phenol-sulphuric acid method. The method has been demonstrated for axenic cultures of the marine diatom Skeletonema costatum and natural marine phytoplankton populations dominated by diatoms. Cellular glucan and cell wall polysaccharides were determined with standard deviations of 1-3% and 2-5%, respectively.