Structure of cell wall and exocellular mannans from the yeast Hansenula holstii. I. Mannans produced in phosphate containing medium

Cell wall mannan and exocellular phosphomannan from Hansenula holstii NCYC 560 were analyzed to determine their structures. Both preparations were composed of a mixture of several polysaccharides (molecular weight = 1x10⁶) differing in degree of phosphorylation and in structural arrangement. The cell wall mannan was a mixture of two branched polysaccharides containing 1,2 and 1,3 linkages, one of the fractions having ß linkages in addition to the a linkages usually found in these polymers. The exocellular phosphomannan was composed of three polymers, all of them with an a 1,6 linked backbone to which a 1,2 and a 1,3 linked side chains of various lengths were attached. The cell wall mannan contained phosphodiester linkages as reported for mannans from other species. However, the highly phosphorylated exocellular mannan was a novel kind of polysaccharide having its phosphates in the monoester form. It is concluded that the exocellular phosphomannan was not a product of autolysis of the cell wall material but rather an independently synthesized material