Abstract
Cyst formation in liquid cultures ofAzotobacter vinelandii could be raised to 90% by including 0.6% CaCO3 in the Burk's basal salts solution. The cysts were resistant to desiccation and possessed exine and intine capsular components when observed by electron microscopy of ultrathin sections.
Cells grown in liquid medium containing no CaCO3, but in which the pH was controlled by addition of 0.1m KOH, were not resistant to desiccation. The capsular material was loosely aggregated and not organized into the typical coat structure. The culture supernatant fluid became viscous and could be precipitated with CaCl2, yielding a thick, polysaccharide-like gel.
Calcium carbonate in the liquid encystment medium served both as a means of acid neutralization and as a source of calcium ions. Calcium ions appear to be structural units necessary for coordination of the coat components into the rigid cyst structure. Other metal ions examined could not substitute effectively for calcium in the encysting system.
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This investigation was supported by Public Health Service research grants AI-02924 and AI-05551 and by Public Health Service predoctoral fellowship 5-F1-GM-29, 322-02.
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Stevenson, L.H., Socolofsky, M.D. Encystment ofAzotobacter vinelandii in liquid culture. Antonie van Leeuwenhoek 38, 605–616 (1972). https://doi.org/10.1007/BF02328126
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DOI: https://doi.org/10.1007/BF02328126