Rf. Vogel et al., THE COMPETITIVE ADVANTAGE OF LACTOBACILLUS CURVATUS LTH 1174 IN SAUSAGE FERMENTATIONS IS CAUSED BY FORMATION OF CURVACIN A, Systematic and applied microbiology, 16(3), 1993, pp. 457-462
Lactobacillus curvatus LTH 1174 produces the bacteriocin curvacin A wh
ich in vitro inhibits the growth of closely related lactobacilli and t
he opportunistic food pathogens Enterococcus faecalis and Listeria mon
ocytogenes. Curvacin A was found in the late exponential growth phase
under conditions simulating those prevailing in fermenting sausage, i.
e. in the presence of salt and at low temperature. In pilot fermentati
ons employing L.curvatus LTH 1174 as starter, this strain gained domin
ance over the fortuitous flora even after inoculation at low cell dens
ities of 10(3) CFU/g. Upon co-inoculation with the highly competitive
commercial starter L.curvatus LTH 683 the bacteriocin-producing L.curv
atus LTH 1174 represented more than 97% of the lactobacilli present in
the sausages after 3 days of fermentation. A plasmid-cured derivative
of L.curvatus LTH 1174 which was unable to produce the bacteriocin ha
d also lost its strong ability to compete with other strains. Thus, th
e production of the bacteriocin is suggested to be the major cause for
the improved competitiveness. The application of bacteriocin-producin
g starter cultures for the manufacture of fermented dry sausages can e
nsure safe performance of the fermentation by suppression of the fortu
itous microflora.