The oxygen and hydrogen in the anaerobic jars react on the catalyst to produce water which removes the free oxygen. Many, perhaps most, bacteria produce capsules under the right conditions. Capsules may be absent, thin, thick, well formed or loose. Capsule formation is dependent upon the nutrient conditions. In general, media rich in sugars and low in nitrogen tend to induce capsule formation.
Capsules play a number of roles in the life of microbes.
Both prokaryotes and eukaryotes form capsules. Provide a food reserve when certain organic compounds are in excess. A virulence determinant of pathogenic microbes. We are most interested in the role capsules play in pathogenicity. Mutants of S .