Cmap. Franz et al., Atypical genetic locus associated with constitutive production of enterocin B by Enterococcus faecium BFE 900, APPL ENVIR, 65(5), 1999, pp. 2170-2178
A purified bacteriocin produced by Enterococcus faecium BFE 900 isolated fr
om black olives was shown by Edman degradation and mass spectrometric analy
ses to be identical to enterocin B produced by E. faecium T136 from meat (P
. Casaus, T. Nilsen, L. M. Cintas, I. F. Nes, P. E. Hernandez, and H. Holo,
Microbiology 143:2287-2294, 1997). The structural gene was located on a 2.
2-kb HindIII fragment and a 12.0-kb EcoRI chromosomal fragment. The genetic
characteristics and production of EntB by E. faecium BPE 900 differed from
that described so far by the presence of a conserved sequence like a regul
atory box upstream of the EntB gene, and its production was constitutive an
d not regulated. The 2.2-kb chromosomal fragment contained the hitherto und
etected immunity gene for EntB in an atypical orientation that is the rever
se of that of the structural gene. Typical transport and other genes associ
ated with bacteriocin production were not detected on the 12.0-kb chromosom
al fragment containing the EntB structural gene. This makes the EntB geneti
c system different from most other bacteriocin systems, where transport and
possible regulatory genes are clustered. EntB was subcloned and expressed
by the dedicated secretion machinery of Carnobacterium piscicola LV17A. The
structural gene was amplified by PCR, fused to the divergicin A signal pep
tide, and expressed by the general secretory pathway in Enterococcus faecal
is ATCC 19433.