The role of selective pressure and selfish DNA in horizontal gene transfer and soil microbial community adaptation

Recent advances in genome sequencing and horizontal gene transfer in soil have led to new insights on soil microbial community adaptation. In this review, we document and evaluate the role of selective pressure and selfish DNA in propagating horizontal gene transfer in soil through the use of a model system involving the organic pesticide 2,4-dichlorophenoxyacetic acid and the metal cadmium. This review provides a theoretical framework for microbial adaptation, wherein it is the selfish nature of DNA that provides the initial stimulus for adaptation rather than the host cells themselves. Subsequent to selfish DNA transfer, if useful to host cells, the transferred DNA may become integrated into the host chromosome. Following these events, ultimately the growth of more fit individuals within the newly created ecological niche allows for adaptation of the soil microbial community.