Broad Host Range Conjugative and Mobilizable Plasmids in Gram-Negative Bacteria

Abstract

Bacterial conjugation mediates genetic exchange not only between cells of the same species but also between members of distantly related or even unrelated genera. These transfer events have been demonstrated among diverse members within both the gram-positive and gram-negative groups of organisms. Recently, experiments using natural conjugation systems have demonstrated gene transfer between gram-positive and gram-negative organisms, and even from bacteria to the lower eukaryote Saccharomyces cerevisiae (59, 124, 125). The significance of this promiscuous gene transfer is that it provides a mechanism for the availability of a huge pool of genes for bacterial evolution. A dramatic example of the ability of individual bacteria to acquire genes of selective value is the widespread development of resistance to antibiotics used in clinical medicine and agriculture.