Isolation of transformation-deficient Streptococcus pneumoniae mutants defective in control of competence, using insertion-duplication mutagenesis with the erythromycin resistance determinant of pAM beta 1.

Several transformation-deficient mutants of Streptococcus pneumoniae were isolated after insertion-duplication mutagenesis. Mutagenesis was accomplished by transformation of competent cells with chimeric DNA formed by the ligation of TaqI fragments of pneumococcal DNA to the erythromycin resistance determinant of the streptococcal plasmid pAM beta 1. The two mutants described were characterized as defective in the control of competence induction, possibly due to a block in the production of the intercellular competence-inducing protein.