Bacterial "competence" genes: signatures of active transformation, or only remnants?

An exhaustive review published ten years ago reported natural genetic transformation, a potential mechanism for intra- and interspecies gene transfer, in approximately 40 species belonging to different taxonomic and trophic groups. Since then, considerable progress has been made in characterizing DNA-uptake machineries and regulatory circuits controlling their expression in cells competent for genetic transformation. In this article, in light of the recent description of a Group A streptococcal isolate capable of DNA transfer in mixed cultures, we discuss whether the detection in completely sequenced microbial genomes of intact homologues of key competence-regulatory and/or DNA-uptake proteins enables the prediction of new transformable species.