It has been reported that the antigenic conversion from 3, 10 to 3, 15 in group E Salmonella is of a nature of lysogenic conversion and the phage responsible for the conversion is obtained from group E
2 and E
3 Salmonellas, and that the antigenic structure of variants is reverted to the original one by cultivating the cells in broth containing anti-15 serum.
This paper deals with the investigation on the relationship between the structure of O antigens and bacteriophage in lactose-fermenting organisms with the complete antigens of S. newington of group E
2.
Strains #2922 and 3534, which have been described by Saphra and Seligmann, were found to produce phages identical with the phage ε
15 in the activity of inducing lysogenic conversion from 3, 10 to 3, 15 in the O antigens of group E Salmonella, plaque morphology, host range, serological specificity, etc. These strains split off lactose slowly fermenting or non-fermenting cells, which are not different from lactose fermenting cells in their lysogenicity. In addition, cells of antigenic structure 3, 10 were isolated when cells of antigenic structure 3, 15 were cultured in broth containing anti-15 serum, as observed in group E Salmonellas.
These strains are similar to Escherichia coil in that they ferment lactose and do not produce H
2S, but on the other hand they have been found by the author to be similar to Salmonella in the activities of amino acid decarboxylases. At the present stage of research, however, it is difficult to say to what extent either of the above properties is important to lysogenic conversion and production of the phage ε
15, since, as will be reported in separate paper, among strains of Escherichia freundii with O antigens 3, 10 the similar lysogenic conversion of O antigens by the phage ε
15 has been observed in a strain which is closely related to Salmonella in various biochemical activities including lactose fermentation but shows the activities of amino acid decarboxylases similar to those of Escherichia.
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