Genomic GC content drifts downward in most bacterial genomes

In every kingdom of life, GC->AT transitions occur more frequently than any other type mutation due to the spontaneous deamination cytidine. eukaryotic genomes, this slow loss GC base pairs is counteracted by biased gene conversion which increases genomic content as part recombination process. However, has not been observed in bacterial so we hypothesized that cause a reduction prokaryotic genomes on an evolutionary time scale. To test hypothesis, used phylogenetic approach analyze triplets closely related representing wide range kingdom. The resulting data indicate drifting downward where comprise 40% or total genome. contrast, containing less have fewer opportunities for relatively stable actually increasing. It should be noted change net shared parts genome and does apply lost acquired since being compared common ancestor. detailed analysis two Caulobacter revealed acquisition mobile elements reduced well.