How much cytoplasm can a bacterial genome control?

In this perspective we discuss that bacterial genomes have optimized during evolution to control a range of cytoplasm, from immediately after cell division to a maximum amount/volume present just prior to DNA replication and subsequent cell division. The genetic expansion of bacteria via evolution may be limited to a genome size: cytoplasm amount/volume ratios and energetics that have been selected for during 3.6-4 billion years of evolution on the Earth. The optimal genome size is one that is relatively constant, but also has some plasticity for evolutionary change (via gene transfer) and mutational events, and can control a range of cytoplasm during the cell cycle. (C) 2010 Elsevier B.V. All rights reserved.