Xenogeneic silencer-like regulators were searched in fully sequenced prokaryote genomes.

Putative xenogeneic silencer regulators are limited to some bacteria and are specific for each division.

Xenogeneic silencer regulators from the H-NS family are the most diversified.

Other nucleoid-associated proteins were also searched and their distribution was also assessed.

Our search updates and extends xenogeneic silencer regulators database.

Results showed that xenogeneic silencer-like regulators are specific for the bacteria they are found in and exclusive, as members of the other families are excluded.