Conjugative Gene Transfer in the Gastrointestinal Environment

This chapter focuses on knowledge on conjugative transfer of antibiotic resistance genes in the animal gut, particularly, on the impact of bacterial transfer physiology and intestinal environment on the kinetics of transfer and establishment of new genetic traits within the gut microbial population. The justified concern about the increasing emergence of antibiotic resistant bacteria focuses about transfer and establishment of resistance genes in the gut. Dissemination of resistance genes in the gut bacterial population can happen either through horizontal transfer, as reviewed, or through vertical transfer. The different mechanisms for exchange of genetic information among intestinal bacteria such as plasmid transfer from gram‐negative bacteria, plasmid transfer from gram-positive bacteria, and conjugative transposition are presented in this chapter. The transfer frequency of conjugative transposons is a product of the frequency of transposons excision from the chromosome and of the transfer event itself, these transposons are transferred in vitro at a much lower frequency than is seen for most conjugative plasmids. Environmental factors also can affect the frequency and outcome of conjugative gene transfer. Impact of the gut environment on conjugative transfer is also discussed in this chapter. Another factor that affects the efficiency of conjugative transfer is the physiological state of the cells involved in the mating. For potent gene transfer mechanisms such as conjugative plasmids, colonization and establishment in the gut is not a prerequisite for genetic exchange.