General Papers

Antonie van Leeuwenhoek

, Volume 54, Issue 4, pp 357-366

First online:

Cyniclomyces guttulatus (Saccharomycopsis guttulata) — culture, ultrastructure and physiology

  • Charles H. ZierdtAffiliated withMicrobiology Service, Clinical Pathology Department, Room 2C-385, Clinical Center, National Institutes of Health
  • , Clay DetlefsonAffiliated withMicrobiology Service, Clinical Pathology Department, Room 2C-385, Clinical Center, National Institutes of Health
  • , Jacqueline MullerAffiliated withDivision of Biochemistry and Biophysics, Center for Drugs and Biologics, Food and Drug Administration
  • , Kimberly S. WaggieAffiliated withComparative Pathology Section, Veterinary Resources Branch, Division of Research Services, National Institutes of Health

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Organisms that form an essential extra inner lining of selected areas of the stomach mucosa occur in mice, rats and some other animals. The yeast Cyniclomyces guttulatus (Saccharomycopsis guttulata) was shown in this study to line the stomach of domestic and feral rabbits, guinea pigs, and chinchillas. The layer of yeast cells formed a loose barrier between lumen contents and mucosal surface. A rapid rate of multiplication in the stomach provided yeast cells that blended in with stomach lumen contents, passed throught the gut, and were finally excreted in large numbers in fecal pellets. Ascospore formation occurred during passage through the large intestine. The layer of yeast cells lining the stomach had no evident salubrious nor deleterious effect on the animal. C. guttulatus grew rapidly from stomach contents or single fecal pellets in a new enriched semisolid medium. Growth was good at pH 1 through 8 on the solidified enriched medium. A very unusual characteristic of C. guttulatus is optimal growht at 38° C, and growth at 42° C, with failure to grow below 30° C. TEM demonstrated a very thick, laminated cell wall which had a thick, filamentous external coating. There were mitochondria, polyribosomes, lipid droplets, and an unusually large central nucleus. The developing spore nucleus became extremely electron dense and encapsulated, along with condensed mitochondria, ribosomes, short membrane sections and other organelles, in a dense lamellar covering.

Key words

Saccharomycopsis guttulata Cyniclomyces guttulatus yeast symbiotic yeast rabbit yeast yeast ultrastructure commensal yeast in rabbit stomach