Isolation of a bacteriocin-producing Lactococcus lactis subsp. lactis and application to control Listeria monocytogenes in Moroccan jben.
OBJECTIVE
Use of a bacteriocin-producing lactococcal strain to control Listeria monocytogenes in jben.


RESULTS
A Lactococcus lactis strain isolated from lben was shown, by the spot technique, to produce a bacteriocin different from nisin. Inhibitory activity of the bacteriocin-producing strain against Listeria monocytogenes was investigated in jben, made from cow's milk fermented with the producer organism and contaminated with 104 or 107 cfu ml-1. Listeria counts were monitored during manufacture, and during conservation at room and at refrigeration temperatures. Results showed that the pathogen was reduced by 2.7 logarithmic units after 30 h of jben processing when the initial inoculum of 107 cfu ml(-1) was used. For the initial inoculum of 104 cfu ml(-1), the bacterium was completely eliminated at 24 h. Furthermore, the use of the bacteriocin-producing starter culture extended the shelf-life of jben by 5 days.


CONCLUSIONS
In situ production of the lactococcal bacteriocin is an efficient biological means of controlling L. monocytogenes in jben and of allowing shelf-life extension.


CONCLUSIONS
The proposed technology will essentially benefit minimally processed dairy products and those made with raw milk.
Benkerroum
N
N
Institut Agronomique et Vétérinaire Hassan II, Département de Microbiologie Alimentaire et Biotechnologie, Rabat, Morocco.
Oubel
H
H
Zahar
M
M
Dlia
S
S
Filali-Maltouf
A
A
D000898:Antibiosis; D001430:Bacteriocins / Q000096:biosynthesis* / Q000494:pharmacology; D002611:Cheese / Q000382:microbiology*; D015169:Colony Count, Microbial; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000302:isolation & purification* / Q000378:metabolism*; D008089:Listeria monocytogenes / Q000254:growth & development*; D009018:Morocco
D001430:Bacteriocins