The complex polysaccharides of the raphid diatom Pinnularia viridis (Bacillariophyceae)

Abstract

A combination of carbohydrate analysis and atomic force microscopy (AFM) was used to characterize the polysaccharides of the pennate diatom, Pinnularia viridis (Nitzsch) Ehrenberg. Polymeric substances were fractionated into those in the spent culture medium (SCM) and those sequentially extracted from the cells with water at 45°C (WW), NaHCO3 containing EDTA at 95°C (HB), and 1 M NaOH containing NaBH4 at 95°C. Carbohydrate, protein, and sulfate were detected in all the fractions, but their relative proportions differed significantly. Nineteen sugars were identified, including pentoses, hexoses, 6-deoxyhexoses, O-methylated sugars, aminohexoses, and traces of uronic acids. To some extent, the..