Extraction of polysaccharides from a species of Chlorella

The objective of this project was to devise a method to recover the total, water-soluble cell-wall polysaccharides of Chlorella. It was found that substantial quantities of polysaccharides could be extracted after treatment of the cells with a mildly acidic solution of sodium chlorite (yield of recovered polysaccharide, 19–22%). Water-soluble (13–19% yield) and 2% NaOH-soluble (3–6% yield) fractions were obtained. A second treatment gave a total yield of water-soluble polysaccharides of 24–25%, while reducing the amount of material soluble in 2% NaOH to 0.3%. Each polysaccharide fraction was composed of 6 different neutral sugars (rhamnose, arabinose, xylose, mannose, galactose, and glucose). There was evidence of the presence of uronic acid in all fractions. An alkaline hydrogen peroxide treatment of the cells resulted in a 19% yield of polysaccharides that were not further examined.