Capsulated Microorganisms

bacteria, yeasts, and mold fungi whose cells are surrounded by a gelatinous capsule consisting chiefly of polysaccharides and protecting the cell against unfavorable external influences. Azotobacter, Leuconos-toc, pneumococcus, and some kinds of asporogenous yeasts (such as Torulopsis) have thick capsules. The existence of capsules is determined by staining specimens or placing them in an india ink preparation; a light zone corresponding to the capsule can then be seen around capsulated microorganisms. Pathogenic capsulated microorganisms become avirulent when they lose their capacity to form capsules.