AUTHOR=Hasegawa Haruka , Suzuki Erika , Maeda Sumio 

TITLE=Horizontal Plasmid Transfer by Transformation in Escherichia coli: Environmental Factors and Possible Mechanisms

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02365

DOI=10.3389/fmicb.2018.02365

ISSN=1664-302X

ABSTRACT=<p>Transformation is one mode of horizontal gene transfer (HGT) in bacteria, wherein extracellular naked DNA is taken up by cells that have developed genetic competence. Sensitivity to DNase, which degrades naked DNA, is the key to distinguishing transformation from the DNase-resistant HGT mechanisms. In general, <italic>Escherichia coli</italic> is not believed to be naturally transformable; it develops high competence only under artificial conditions, including exposure to high Ca<sup>2+</sup> concentrations. However, <italic>E. coli</italic> can reportedly express modest competence under certain conditions that are feasible in natural environments outside laboratory. In addition, recent data suggest that environmental factors influence multiple routes of transformation. In this mini review, we (1) summarize our studies on transformation-based HGT using <italic>E. coli</italic> experimental systems and (2) discuss the possible occurrence of transformation via multiple mechanisms in the environment and its possible impact on the spread of antibiotic resistance genes.</p>