Isolation and Characterization of a Transformation Deficient Mutant of Streptococcus pneumoniae that is Defective in the Production of an Activator

Transformation deficient mutants were isolated by nitrosoguanidine mutagenesis. A mutant Tra-12 was defective in the spontaneous development of competence for genetic transformation during culture growth, and showed no activator (competence inducing factor) activity inside or outside of the cells throughout growth. However, Tra-12 exhibited normal competence after the addition of an activator extracted from the wild type strain. This mutant needed a much larger quantity of the activator to develop a saturating level of competence and the induced competence disappeared more rapidly than in the wild type strain.