Effect of growth conditions on the structure of β-?-glucans from Phytophthora parasitica dastur, a phytopathogenic fungus

Several glucans have been isolated from the cell walls of Phytophthora parasitica, a phytopathogenic fungus of carnation. These polysaccharides consist of a mixture of (1 --> 3), (1 --> 6)-beta-D-glucans whose molecular masses varied from 7.5 x 10(3) to 2 x 10(6) daltons. All these polysaccharides have a main chain of beta-(1 --> 3)-linked D-glucose residues. They differ in the presence of 1 --> 6 branched oligosidic chains with 1, 2 or 4 D-glucose residues. The effect of various growth conditions on the nature of these glucans have been studied. When asparagine and a high concentration of glucose were present in the culture medium and when the culture was shaken, the production of the lowest molecular weight polysaccharides and their degree of branching were increased.