ULTRASTRUCTURE OF MICROBODIES OF METHANOL-ASSIMILATING YEASTS

Abstract

The fine structure of yeasts capable of utilizing methanol as the sole source of C, Candida sp., Saccharomyces sp. and Torulopsis sp., was studied by EM. Many large microbodies were observed in clustered form in methanol-grown cells. They were observed as refractile granules under a phase contrast microscope. The membrane of the microbody was not stained by a method which specifically stains the plasmalemma, and an asymmetric distribution of the particles between the freeze-fractured half membranes was demonstrated. Microbodies in cells at the stationary phase of growth contained crystalline inclusions; crystalloids from Candida showed a tetragonal pattern, while those from Saccharomyces presented a hexagonal one. The development of microbodies was studied both during normal growth in the methanol medium and during the period of adaptation which occurs upon transfer from glucose to methanol medium. The possible modes of synthesis of the structure were discussed.