[1] Free Univ Amsterdam, Dept Phys & Astron, Phys Complex Syst, Fac Sci, NL-1081 HV Amsterdam, Netherlands
[2] Univ Strasbourg 1, CNRS, FRE2326, Lab Dynam Evolut & Express Genomes Microorganisme, Strasbourg, France
[3] Inst Pasteur, Unite Genet Genomes Bacteriens, Paris, France
[4] Univ Dusseldorf, Inst Phys Biol, D-4000 Dusseldorf, Germany