Prokaryotic genomes in the light of genomic analyses

Genomic analyses revealed that prokaryotic genomes are very diverse. They differ in size, architecture and genetic information which they encode. The plasticity of the genomes is the result of several factors, including (i) horizontal gene transfer (responsible for the acquisition of exogenous DNA), (ii) genetic rearrangements (resulting from diverse recombinational events), and (iii) genome reduction, which leads to the loss of genetic information of a low adaptative value. The insertions and deletions of DNA permanently alter the genomes and result in adaptation of the microorganisms to their specific environments by genome optimization. For this reason we observe a straight correlation between metabolic versatility of prokaryotes and the size of their genomes.