Plasmid Transfer in the Ocean - A Case Study from the Roseobacter Group.

摘要: Plasmid mediated horizontal gene transfer (HGT) has been speculated to be one of the prime mechanisms for adaptation roseobacters (Rhodobacteraceae) their ecological niches in marine habitat. Their plasmids contain ecologically crucial functional modules up 40-kb size e.g. aerobic anoxygenic photosynthesis, flagellar formation and biosynthesis antibiotic tropodithietic acid. Furthermore, widely present type four secretion system (T4SS) shown mediate conjugation across genus barriers, albeit laboratory. Here we discovered that Confluentimicrobium naphthalenivorans NS6T, a tidal flat bacterium isolated Korea, carries 185-kb plasmid, which exhibits long-range synteny with conjugative 126-kb plasmid Dinoroseobacter shibae DFL12T. Both replicons are stably maintained by RepABC operons same compatibility group (-2) they harbor homologous T4SS. Principal component analysis codon usage shows large similarity between two plasmids, while chromosomes very distinct, showing neither bacterial species represents original host those RepABC-2 plasmids. The do not share common habitat today phylogenetically only distantly related. Our finding demonstrates first clear-cut evidence conjugational biogeographical phylogenetic barriers Rhodobacteraceae documents importance HGT ocean.