Lambda kil-mediated lysis requires the phage context

The lambda kil gene has been shown to be responsible for premature lysis effected by addition of chloramphenicol between 15 and 20 min after thermal induction of a lambda prophage. Here, we localized the kil reading frame. The kil gene, represented by lambda orf47, overlaps genes cIII and gam. Expression of the plasmid-borne kil gene resulted in growth arrest, a reduction of colony-forming units and filament formation. However, kil-mediated cell lysis could not be triggered by chloramphenicol when the plasmid borne kil gene was expressed, suggesting that kil-induced cell lysis requires the phage context.