A process for the production of beta-3-(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.