Escherichia coli females defective in conjugation and in adsorption of a single stranded deoxyribonucleic acid phage

Abstract

It was predicted that, among mutants resistant to infection by single stranded deoxyribonucleic acid viruses, there would be some also resistant to 'infection' by single stranded conjugal deoxyribonucleic acid. Approximately 55% of the E. coli K 12 females selected for resistance to phage ST 1 were defective as recipients in conjugation. These spontaneous mutants fell into 2 classes. Type A accepted both plasmid and chromosomal markers at greatly reduced frequencies (<10-6 of normal for at least one strain), formed 'rough' colonies, and (unlike their parent) were nonflagellated. Type B strains accepted both chromosomal and plasmid markers at reduced frequencies (10-2 to 10-1 of normal), were temperature sensitive for growth, and showed increased susceptibility towards antibiotics and deoxycholate. Both classes of mutants also were resistant to certain female specific viruses.