Abstract
The biochemical characteristics of 25 strains of the genus Serratia isolated from the stools, sputum, infected areas of humans and from the air were studied, and the following results were obtained:
I) Some strains did not produce prodigiosin known as the pigment characteristic to the genus Serratia, although they showed the same biochemical characteristics as the pigment-producing strains. And, it was also noted that a large number of strains were lactose non-fermenters.
2) For this reason, it is believed that in isolating the members of the genus Serratia the main emphasis placed on the ability to split lactose and to produce prodigiosin is not always appropriate.
3) It seems difficult to differentiate the three species of S. marcescens, S. indica and S. plymuthica by biochemical studies only.
