Lyophilized preparations of bacteriocinogenic Lactobacillus curvatus and Lactococcus lactis subsp. lactis as potential protective adjuncts to control Listeria monocytogenes in dry-fermented sausages.
OBJECTIVE
Study of the effectiveness of in situ bacteriocin production by lactic acid bacteria (LAB) to control Listeria monocytogenes in dry-fermented sausages.


RESULTS
Two bacteriocin-producing strains: Lactococcus lactis subsp. lactis LMG21206 and Lactobacillus curvatus LBPE were grown in a pilot scale fermentor and lyophilized to be directly used in dry sausage fermentation. A commercial starter culture (Bel'meat SL-25) not inhibitory to L. monocytogenes (Bac- starter) was mixed (1 : 1) with each of the two lyophilized bacteriocin-producing strains to obtain starters active against the pathogen (Bac+ starter). Anti-Listeria effectiveness of the Bac+ starters was studied in dry-fermented sausages. The meat batter was experimentally contaminated with a mixture of four different strains of L. monocytogenes (10(2)-10(3) CFU g(-1)). The results showed that L. monocytogenes did not grow in any of the contaminated batches, but no significant decrease (P > 0.05) was observed either in the positive control (no added starter culture) or in samples fermented with the Bac- starter culture during the fermentation period and up to 15 days of drying. When the Bac+ starter contained Lb. curvatus LBPE, cell counts of L. monocytogenes decreased to below the detectable limit (<10 CFU g(-1)) after 4 h of fermentation and no survivors could be recovered by enrichment beyond day 8 of drying. When the Bac+ starter culture containing Lc. lactis LMG21206 was used, a decrease in Listeria counts to below the detectable limit was achieved after 15 days of drying.


CONCLUSIONS
The bacteriocin-producing strains studied may be used as adjunct cultures for sausage fermentations to control the occurrence and survival of L. monocytogenes.


CONCLUSIONS
Addition of the Bac+ strains, especially the Lb. curvatus strain would provide an additional hurdle to enhance the control of L. monocytogenes in fermented meat products.
Benkerroum
N
N
Département des Sciences Alimentaires et Nutritionnelles, Institut Agronomique et Veterinaire Hasssan II, Rabat, Morocco. n.benkerroum@iav.ac.ma
Daoudi
A
A
Hamraoui
T
T
Ghalfi
H
H
Thiry
C
C
Duroy
M
M
Evrart
P
P
Roblain
D
D
Thonart
P
P
D001430:Bacteriocins / Q000096:biosynthesis; D005285:Fermentation; D005516:Food Microbiology; D005519:Food Preservation; D007778:Lactobacillus / Q000378:metabolism; D013294:Lactococcus lactis / Q000378:metabolism; D008461:Meat Products
D001430:Bacteriocins