COLICIN-B AND COLICIN-IA AS NOVEL COUNTERSELECTIVE AGENTS IN INTERSPECIES CONJUGAL DNA TRANSFERS FROM COLICIN-SENSITIVE ESCHERICHIA-COLI DONORS TO OTHER GRAM-NEGATIVE RECIPIENT SPECIES

Colicins are powerful counterselective agents in conjugal DNA transfer s using colicin-sensitive Escherichia coli donor strains and colicin-r esistant recipient species. We have constructed a high-level constitut ive expression system for the bacteriocin and immunity genes of channe l-forming colicins B and Ia to optimize production of these colicins a s molecular biology reagents.