S. Wessels et Hh. Huss, SUITABILITY OF LACTOCOCCUS-LACTIS SUBSP LACTIS ATCC-11454 AS A PROTECTIVE CULTURE FOR LIGHTLY PRESERVED FISH PRODUCTS, Food microbiology, 13(4), 1996, pp. 323-332
This study is part of strategy to control the human pathogen Listeria
monocytogenes in lightly preserved fish products by using food-grade l
actic acid bacteria. When the nisin-producing Lactococcus lactis subsp
lactis ATCC 11454 was cultured in the same vessel as L-monocytogenes
Scott A in brain-heart infusion broth (BHI) at 30-degrees C, the patho
gen declined from 5x10(5) to fewer than 5 cfu ml(-1) within 31 h. The
effect was not due to lactic acid inhibition. Growth and nisin product
ion by L-lactis ATCC 11454 were investigated under the conditions of t
emperature and salt used for light preservation. At 5-degrees C in M17
broth, the organism grew well ans produced nisin. In an infusion of c
old-smoked salmon the organism did not grow at 5-degrees C, althoigh i
t did at 10-degrees C. NACl up to 4% allowed for efficient growth and
nisin production, while 5% NaCl resultes in very slow growth and no de
tectable nisin. On slices of commercial cold-smoked salmon at 10-degre
es C, no net propagation pf L-lactis ATCC 11454 could be detected with
in 21 days. However, when salmon slices were inoculated with L-mycocyt
ogenes at 10(4) cfu g(-1) and a 300-fold excess of washed lactococcus
cells, the pathogen's population declined a half log the first 1-5 day
s, then increased at a rate slightly lower than that of the control no
t inoculated with the lactococcus.