tetA(L) Mutants of a Tetracycline-Sensitive Strain of Bacillus subtilis with the Polynucleotide Phosphorylase Gene Deleted

A Bacillus subtilis strain with the polynucleotide phosphorylase gene deleted was sensitive for growth in the presence of tetracycline. This strain was used to select for tetracycline-resistant mutants. A point mutation in the tetA(L) promoter and a spontaneously occurring tetA(L) gene copy number mutant were characterized.