The Vibrio cholerae bacteria resistance against introduction of new genetic material through transformation is caused mainly by a small extracellular or periplasmic endonuclease of type I, the VcEndA of 24.7 kDa coded by the dns gene, (Focareta et al, 1987; Focareta et al, 1991; Altermark et al, 2007b). The VcEndA homologues in other bacteria, Serratia marcescens (Timmins et al, 1973), Erwinia ...