Relationship between pigment production and haemolysin formation by Lancefield group B streptococci.

Group B streptococci produce both a pigment and a haemolysin. The requirements of group B streptococci for the formation and release of pigment and haemolysin are similar and have been examined to extend observations on the relationship between the two products. The amount of pigment and haemolysin extractable from actively metabolising washed-cell suspensions of group B streptococci varied with the atmosphere of incubation, the pH at which the extraction was carried out and the presence of Mg2+ ions. Both pigment and haemolysin were produced in significant amounts in all phases of the growth cycle. When conditions were established for obtaining maximum yields of haemolysin, its production correlated closely with pigment yields, but pigment did not function as a carrier for haemolysin. Formation of pigment, but not of haemolysin, increased in the presence of trimethoprim or higher concentrations of glucose. The composition of pigment produced in different conditions differed qualitatively and different strains of group B streptococci formed pigment of different appearance, suggesting that group B streptococcal pigment is composed of several different substances.