Optimized Bacterial Conjugation Strains

Reliable plasmid modification and conjugation in a single strain

E. coli Conji

Problem: Conjugation is an important method for the genetic modification of bacteria since it allows the transfer of plasmids between a broad range of bacteria and beyond. While plasmid modification is usually performed in a lab strain like DH10B, conjugation requires the transfer of the modified plasmid into a conjugation-proficient E. coli donor strain like S17. This additional transformation step adds significantly to the time until conjugation can be performed. Furthermore, it increases the risk of unintended plasmid modifications and adds to the costs due to necessary plasmid preparations and analyses.

Solution: We took the gene clusters necessary for the conjugation (~ 55 kbp) from E. coli S17 and introduced them in the genome of E. coli HS996, a cloning host similar to DH10B. Additionally, we introduced the pir-gene to allow strain engineering strategies based on integrative R6K-plasmids. The new strain “Conji-pir” combines the advantages of a cloning strain with the capability to transfer a modified plasmid directly via conjugation.

The strain was first presented at the “International Rhodobacter-Symposium 2025” in Wageningen (klick for further details) and is available on request.