An autolysin dissolves the inner cell wall layer of the algaPediastrum (Hydrodictyaceae)

Summary An autolysin produced by young colonies ofPediastrum frees them from the vesicle in which they are formed within 12 hours of release of zoospores from the parent cell. The polysaccharide vesicle is derived from the inner wall layer of the parent cell. Refrigeration delays vesicle disintegration; boiling stops it completely. A purified, lyophilized extract of the vesicle fluid added to boiled vesicled colonies removes the vesicle in 2 hours with the release of reducing sugars and polysaccharides.Biogel P2 and P10 chromatography of the products following incubation of the enzyme preparation and wall showed no more than 1% oligosaccharides; the remaining carbohydrates had a molecular weight of several thousand daltons. Analyses of isolated vesicle wall material (70–85% of the dry weight) showed mannose accounting for approximately 50% of the dry weight, with none of the other neutral sugars present (fucose, xylose, galactose and glucose) representing more than 3%. Uronic acids account for 20–25% of the wall weight, and proteins less than 2%. Pediastrum colonies are thus freed from the vesicles in which they are formed by the action of an autolysin they produce. The autolysin acts on the vesicle wall material to generate reducing sugars and cause it to disintegrate into its constituent polysaccharides.