Formation of rough and smooth strains ofSphaerotilus discophorus
- Cite this article as:
- Stokes, J.L. & Powers, M.T. Antonie van Leeuwenhoek (1965) 31: 157. doi:10.1007/BF02045886
- 18 Downloads
Sphaerotilus discophorus forms characteristic filamentous dark brown colonies on dilute organic media containing managanous salts. Spontaneously or by induction the organism may produce an entirely different kind of colony, the S type which is smooth, glistening, hemispherical with a regular edge, and colorless. The latter resembles, therefore, colonies of common bacteria. The S colony may be a temporary modification imposed by nutritional conditions or a mutation.
Temporary S-colony modifications occurred when a 0.5% peptone, mineral salts agar was enriched with 0.2 to 1.0% glucose, galactose, mannitol, sucrose or salicin but not with raffinose, glycerol or Na lactate. Two per cent peptone and 0.5% tryptose also stimulated temporary S-colony formation. However, the dark brown pigmentation, i.e. MnO2 deposition, persisted in contrast to its marked repression by sugars. Phytone and tryptone are partially effective in S-colony formation and proteose-peptone is ineffective.
Mutations of R to S strains were obtained by ageing broth cultures of R strains. The mutant S strains were identical to the parent R strains in nutritional and physiological properties but differed apparently in that they did not form sheaths or oxidize manganous salts.