Plasmid-associated bacteriocin production by a strain of Carnobacterium piscicola from meat

Abstract

Carnobacterium piscicola LV17 isolated from vacuum-packed meat produces bacteriocin(s) that is active against closely related lactic acid bacteria, Enterococcus spp., and a strain of Listeria monocytogenes but not against gram-negative bacteria. The bacteriocin has a bactericidal mode of action, is heat resistant, and is stable over a wide range of pH but is inactivated by proteolytic enzymes. Sensitive and resistant cells were shown to adsorb the bacteriocin, but cell death depended on contact of the bacteriocin with the cell membrane. Bacteriocin production is detected early in the growth cycle of the organism in APT broth, but it is not produced in APT broth adjusted to pH 5.5. Bacteriocin production and resistance to the bacteriocin produced are associated with two plasmids of 40 and 49 megadaltons. The possibility that two bacteriocins are produced is indicated because the inhibitory substances of the mutant strains containing either the 40or 49-megadalton plasmids have different antimicrobial spectra.

Genetics of bacteriocins produced by lactic acid bacteria

“…Many strains have been reported to produce bacteriocins [189] with most being active against Enterococcus and Listeria species, in addition to other LAB. It has been suggested that the predominance of this species in chilled meats results from a competitive advantage imparted by bacteriocins produced early in their growth phase [190]. This ecological role can now be readily evaluated given the current availability of Bac + and Bac variants of Carnobacterium strains, as well as other LAB, that have been isolated from chilled meats [187,191].…”

“…Carnocins are typically heat stable and active over a pH range of 2-8, even though bactcriocin production may not occur below pH 5.5 where growth is restricted [87,190]. Carnocin U149 is produced by a Carnobacterium species isolated from fish [87].…”

“…('. pis'cicola LVI7 produces two plasmid-encoded bacteriocins, designated as 'carnobacteriocins' A and B [190,191]. Biochemical characterization has tentatively defined each carnobactcriocin in at least three active forms which have yet to be sequenced and characterized [9].…”

“…Biochemical characterization has tentatively defined each carnobactcriocin in at least three active forms which have yet to be sequenced and characterized [9]. Carnocin A is encoded by a 40-MDa plasmid (pCP40, 60kb) and is produced late in the growth cycle, whereas carnocin B, encoded by a different 49 MDa plasmid (pCP49, 74kb], is produced within the early growth stages of the bacterium [190,191]. Partial levels of bacteriocin production and immunity were lost upon curing of pCP40 or pCP49 indicating that each plasmid encoded production and immunity determinants for a distinct portion of the bacteriocin activity.…”

Divergicin 750, a novel bacteriocin produced by Carnobacterium divergens 750

“…Little is known about bacteriocins from carnobacteria. Some bacteriocin-producing carnobacteria have been identified [6,7]. We have previously purified and characterised piscicolin 61 from ocin BMl and B2 show significant sequence similarity and contain the -YGNGVXC-motif typical of bacteriocins active against Listrricr.…”