A process for the production of .beta.-(1,3)(1,6) glucan from a glucan
containing cellular source is described, together with compositions and
uses/methods of treatment involving glucan. The process of the invention
comprises the steps of: (a) extracting glucan containing cells with
alkali and heat, in order to remove alkali soluble components; (b) acid
extracting the cells of step (a) with an acid and heat to form a
suspension; (c) extracting the suspension obtained of step (b) or
recovered hydrolyzed cells with an organic solvent which is non-miscible
with water and which has a density greater than that of water separating
the resultant aqueous phase, solvent containing phase and interface so
that substantially only the aqueous phase comprising .beta.-(1,3)(1,6)
glucan particulate material remains; wherein the extraction with said
organic solvent provides separation of glucan subgroups comprising
branched .beta.-(1,3)(1,6)-glucan, and essentially unbranched
.beta.-(1,3) glucan which is associated with residual non-glucan
contaminents; and (d) drying the glucan material from step (c) to give
microparticulate glucan.