Genome-wide screen for Escherichia coli genes involved in repressing cell-to-cell transfer of non-conjugative plasmids

► Cell-to-cell transfer of non-conjugative plasmids occurs in Escherichia coli co-culture. ► We screened for 'transfer-up mutants' using Keio knock-out mutants as recipients. ► Those transfer-up mutants showed ≈2-30-fold promotion of plasmid transfer. ► Two competence-gene homologues (ybaV and yhiR) were identified in our screen.