Pigment production in group B streptococci

Most haemolytic group B streptococci produced a yellow to orange pigment in Colombia agar and in some Todd Hewitt broths. The composition of the broth medium was important. Trypsin inhibited pigment production, but had no effect on pigment already produced. Optical density measurement revealed three main peaks at 420, 260 and 215 nm respectively with pigment producing strains. Nonpigmented strains gave only the two peaks at 260 and 215 nm.