Pigment Production by Staphylococci

Summary: White variants, which were stable over many generations, were isolated from six of eight strains of Staphylococcus aureus by cultivation in fluid medium; their incidence was favoured by 0·5% (w/v) lithium chloride. These variants all resembled the parent culture from which they were derived in the production of free coagulase and α-lysin and, except for one which was non-typable, in bacteriophage type. None of the white variants, however, was clumped by plasma in a slide test, although the parent cultures were.

Golden variants were isolated from two old laboratory strains of coagulase-positive staphylococci which had become white and from three of six white variant cultures isolated in the study of ‘aureus→albus’ variation. These golden variants were isolated under conditions which are unfavourable to the growth of staphylococci in the laboratory. They resembled the parents from which they were derived in production of free coagulase and α-lysin and in bacteriophage type. They differed from the parent cultures in production of the factor which causes clumping in plasma, and showed a non-specific increase in resistance to various antibacterial agents.