Physical and genetic map of the Listeria monocytogenes EGD serotype 1/2a chromosome

Listeria monocytogenes is a facultative intracellular pathogen responsible for both invasive and non-invasive food-borne illness in animals and humans . In this study, macrorestriction analysis following: pulsed-field gel elec trophoresis was used to show that Listeria monocytogenes serovar 1/2a strai n EGD has a single chromosome containing eight NotI fragments of 1100, 850, 365, 320, 275, 40, 30 and 20 kb in size and 11 Asci fragments of 860, 470, 410, 360, 320, 250, 110, 80, 50, 30 and 20 kb. The total genome therefore comprises 3000 +/- 50 kb, The creation of a physical and genetic map of the Listeria genome was achieved by generating NotI linking clones and their u se in subsequent hybridisation analysis. Using isogenic mutants harbouring additional artificial NotI restriction sites, we were able to precisely map the positions of all currently known virulence genes on the chromosome. (C ) 1999 Federation of European Microbiological Societies. Published by Elsev ier Science B.V. All rights reserved.