Competence development has so far been described for B. subtilis, B. licheniformis and B. amyloliquefasciens, but not for B. cereus or its relatives. Recent studies indicate that pathogens belonging to the B. cereus group (e.g. B. cereus, B. anthracis and B. thuringiensis) have adapted to various environments because of insertion of DNA through homologous recombination. We aim to determine if a functional system for natural transformation exists in Bacillus species: by developing genetic engineering tools that enable us to elucidate how competence proceeds, these organisms can subsequently be employed as model systems to describe the high level of genome plasticity observed in this bacterium and amongst related bacteria such as B. anthracis and B. thuringiensis. Natural competence presents also a powerfull tool for molecular genetic studies with these organisms. Aim: Recent results in our laboratory showed, that B. cereus ATCC14579 can become naturally competent. When expressing the B. subtilis ComK protein using an IPTG inducible system in B. cereus ATCC14579, cells grown in minimal medium displayed natural competence, as either genomic DNA or plasmid DNA was shown to be taken up by the cells and integrated into the genome or stably maintained, respectively. This work proves that a sufficient structural system for DNA uptake exists in B. cereus. Using this ComK overexpression system, we aim to understand how DNA is taken up in B. cereus, to get more insight in the regulation of competence related genes and on the role of the two ComK proteins.