Interaction in the Germfree Mouse Intestine of Colicinogenic and Colicin-Sensitive Microorganisms

Synthesis of colicin, per se, by colicinogenic bacteria does not contribute significantly, if at all, toward a selective advantage in competition for dominance in gastrointestinal colonization. Per os inoculation of germfree mice with a slow lactose fermenting CA-62 colicinogenic bacteria and a colic-in-sensitive E. coli K-12 (Row) resulted in no suppression of the latter. When fecal samples were examined over a 4-week period, the colicin-sensitive E. coli actually outnumbered the colicin producer.