Some physical investigations of the behavior of bacterial surfaces VIII. Studies on the capsular material of Streptococcus pyogenes

1. 1. On repeated washing in phosphate buffer solution the electrophoretic mobility of young cells of M variants remained unchanged: the mobility of young G cells, however, always decreased to the value characteristic of old cells of that strain. 2. 2. There was a correlation between the hyaluronic acid content of the cells and the electrophoretic mobility for a large number of strains during growth; both the mobility value and the hyaluronic acid content increased to a maximum at the end of the logarithmic growth phase and decreased to the original value during the stationary phase. 3. 3. The variation of the mobility with the pH of the suspending medium of 24-h cells of the M and G variants of a number of different types confirms the presence of both amino and carboxyl groups on the surface. Further information on the nature of the surface was obtained by treatment of the cells with hyaluronidase.