Transformation and transduction in recombination-defective mutants of Bacillus subtilis

The effects on transformation and transduction of an ultraviolet sensitivity (uvr(-)) and two ultraviolet sensitivity-recombination deficiency (rec-1(-) and rec-2(-)) mutations in isogenic strains of Bacillus subtilis were investigated. Transformation frequency in the rec-1(-) and rec-2(-) strains was reduced to approximately 5 and 25%, respectively, of the parental strains. Normal kinetics of deoxyribonucleic acid dose response in transformation were found for the rec-1(+) and rec-2(-) strains. Biphasic curves were obtained with the rec-1(-) strains. Transduction frequency with bacteriophage SP-10 decreased parallel to transformation frequency in the rec-1(-) and rec-2(-) strains. This result suggests that transformation and SP-10 transduction share a common mechanism for genetic recombination. It also indicates that the reduction in transformation frequency of these strains was not due to altered competence. Transduction frequency with bacteriophage PBS-1 or 3NT, on the contrary, was not diminished in rec-1(-) strains. This frequency was reduced in rec-2(-) strains but not as severely as that of transformation or SP-10 transduction. Several hypotheses to interpret these differences are presented. Recombination frequency betwe...Continue Reading