A modifier mutation affecting utilization of mannitol in pneumococcus.

The altered growth of a pneumococcal mutant containing marker M, which confers ability to utilize mannitol, and a modifier gene is reported. The modifier gene is closely linked to the M gene and imposes a requirement for growth in 0.4% glucose before growth in mannitol medium. The tentative position of the M gene of pneumococcus is ery-r str-r M sul-rd.