Characterization and cloning of the genes encoding enterocin 1071A and enterocin 1071B, two antimicrobial peptides produced by Enterococcus faecalis BFE 1071

The pH-neutral cell supernatant of Enterococcus faccalis BFE 1071, isolated from the feces of minipigs in Gottingen, inhibited the growth of Enterococ cus spp, and a few other gram-positive bacteria. Ammonium sulfate precipita tion and cation-exchange chromatography of the cell supernatant, followed b y mass spectrometry analysis, yielded two bacteriocin-like peptides of simi lar molecular mass: enterocin 1071A (4.285 kDa) and enterocin 1071B (3.899 kDa). Both peptides are always isolated together. The peptides are heat res istant (100 degrees C, 60 min; 50% of activity remained after 15 min at 121 degrees C), remain active after 30 min of incubation at pH 3 to 12, and ar e sensitive to treatment with proteolytic enzymes. Curing experiments indic ated that the genes encoding enterocins 1071A and 1071B are located on a 50 -kbp plasmid (pEF1071). Conjugation of plasmid pEF1071 to E.faecalis strain s FA2-2 and OGX1 resulted in the expression of two active peptides with siz es identical to those of enterocins 1071A and 1071B, Sequencing of a DNA in sert of 9 to 10 kbp revealed two open reading Frames, ent1071A and ent1071B , which coded for 39- and M-amino-acid peptides? respectively. The deduced amino acid sequence of the mature Ent1071A and Ent1071B peptides showed 64 and 61% homology with the alpha and beta peptides of lactococcin G, respect ively. This is the first report of tno nem antimicrobial peptides represent ative of a fourth type of E. faecalis bacteriocin.