Abstract
A number of Shigella strains were examined of their H2S production and following results were obtained :
1. Among the strains of genus Shigella, it was found that some produce H2S by the usual method of cultivation and some by the use of special method, while the others fail to produce any detectable amount of H2S.
2. Therefore, Shigella may not always be excluded from H2S producing bacteria.
3. No significant biochemical difference was recognized between the H2S producing and non-producing strains of Shigella.
4. Shigella strains capable of strongly producing H2S dissociate an extremely small number of H2S strongly producing colonies, weakly producing ones and a large number of so-called non-producing colonies. On the contrary, the possibility of the dissociation of strongly producing colonies from H2S non-producing strains was also recognized.
5. The ability of H2S production may be influenced by various factors such as the kind and concentration of the peptone used, kind of the broth, the concentration of sodium chloride, pH of the medium and further by the method of cultivation employed.
6. Shigella strains have a tendency to diminish or lose their ability to produce H2S while undergoing subcultures and this character is variant depending on the strain used.
7. When the production of H2S is discussed on Shigella strains, it is considered indispensable to describe on the medium and the method of cultivation etc. employed.
