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

Cell wall mannan and exocellular phosphomannan from Hansenula holstii NCYC 560 grown under phosphate limited conditions were analyzed to determine their structures. Both preparations were homogeneous with respect to molecular weight (1x10⁶), but heterogeneous toward ion exchange resins. Mannans studied were reduced in their phosphate content with O acetyl groups replacing most of the phosphates as constituents of these polymers. Both mannans had a branched structure similar to some extent to that described for Saccaromyces cerevisiae cell wall mannan, the main difference being the incorporation of O acetyl groups within the molecules. A role as ion exchanger in the outer regions of the cell wall is proposed for these mannans.