Glycogen and other soluble glucans from chytridiomycete and oomycete species

Dry weight, protein, lipid, and glycogen were determined at various times during cultivation of the Chytridiomycetes, Rhizophydium sphaerotheca and Monoblepharella elongata. M. elongata had relatively stable levels of glycogen, but, in R. sphaerotheca, glycogen levels showed significant changes, particularly in older cultures in which a depletion of glycogen was accompanied by a marked thickening of the cell walls. Glycogen was a significant cellular constituent in both chytridiomycete species. In R. sphaerotheca and M. elongata, respectively, glycogen accounted for as much as 6% and 8.1% of the dry weight. In purified glycogens of both species, only alpha-1,4- and alpha-1,6-linked glucosyl residues were detected and the absorbance spectra of I2-complexes were similar to those of other well characterized glycogens. Purified Rhizophydium glycogen had a beta-amylolysis limit of 43%, and a CL of approximately 12. For the Monoblepharella polysaccharide, the respective values were 45% and 11. In extracts of the Oomycetes, Pythium debaryanum, Mindeniella spinospora, and Apodachlya sp., only beta-1,3- and beta-1,6-linked glucosyl residues were detected. These glucans were not iodophilic nor were they sensitive to alpha-amylase and beta-amylase. The properties of the oomycete polysaccharides suggested that they were similar to the mycolaminarans of Phytophthora spp. Although both investigated chytridiomycete species produced glycogen with typical properties, glycogen was apparently absent in the investigated Oomycetes.