Characterization and incidence of pigment production by human clinical group B streptococci.

Pigment was produced in stab cultures by 97% of 297 group B streptococci isolated from human clinical specimens. The pigment, which was associated with a membranous cell fraction, showed a four-banded absorption spectrum similar to that of a carotenoid, with maxima at 435, 566, 485, and 525 nm. Addition of glucose to the growth medium suppressed pigment production in most strains. Only 37% of strains from bovine sources produced pigment.