微生物生態系における細菌の遺伝子水平伝播現象

抄録

Horizontal gene transfer (HGT) plays an important role in bacterial evolution and the exchange of genetic material between different species and genera. Recently, whole genome analysis demonstrated that HGT also played an important role in the diversification of all three domains of organisms. Bacterial HGTs are mediated by one of three mechanisms: transformation, conjugation, or transduction. In addition to these distinct mechanisms, gene transfer agent (GTA) or membrane vesicles (MV) mediate a transduction-like process that has been reported as an alternative HGT process. The occurrence of HGT has been confirmed by both laboratory and field studies. Both biotic and abiotic parameters affect the success of gene transfer events in natural environments. However, the frequency and the role of HGT in natural environments are currently not well understood due to the difficult nature of defining the experimental conditions required in order to elucidate this important parameter in HGT events. This knowledge will help in the estimation of the emergence of antibiotic resistance genes among bacteria and the potential consequences of the environmental usage of genetically modified bacteria for bioremediation purposes. The aim of this review was to summarize the brief history of HGT and the biotic factors that may affect the frequency of HGT in the ecosystem.