Selective autocytotoxicity in a model system of Escherichia coli K-12 recombinants

Autocytotoxicity was shown by Lac(+) recombinant strains of Escherichia coli K-12 when their growth was inhibited in media containing o-nitrophenyl-beta-d-galactopyranoside. Lac(-) strains without lactose permease or beta-galactosidase activity grew well. Selective autocytotoxicity was shown by simultaneous inhibition of Lac(+) cells and multiplication of Lac(-) cells grown together in this medium.