Development and Testing of Improved Suicide Functions for Biological Containment of Bacteria

Steen Knudsen, Peter Saadbye, Lars H. Hansen, April Collier, Bodil L. Jacobsen, Jørgen Schlundt, Olle H. Karlström

Research output: Contribution to journalJournal articleResearchpeer-review


We have developed very efficient suicide functions for biological containment based on the lethal Escherichia coli relF gene. The suicide functions are placed in duplicate within a plasmid and arranged to prevent inactivation by deletion, recombination, and insertional inactivation. The efficiency of this concept was tested in a plasmid containment system that prevents transfer of plasmids to wild-type bacteria. Protection against plasmid transfer was assayed in test tubes and in rat intestine. Protection was efficient and refractory to inactivation by mutation and transposons. The efficiency of the suicide system was also tested in soil and seawater. We show that unprecedented suicide efficiency can be achieved in soil and seawater after suicide induction by IPTG (isopropyl-beta-D-thiogalactopyranoside). More than 7 orders of magnitude reduction in suicide bacteria was achieved.
Original languageEnglish
JournalApplied and Environmental Microbiology
Issue number3
Pages (from-to)985-991
Publication statusPublished - 1995
Externally publishedYes


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