Modelling interactions between bacteriocin-producing sausage starter cultures or cocultures and Listeria reveals how to improve the efficiency of Listeria killing.

摘要

The kinetics of Listeria innocua LMG 13568 were studied in vitro during laboratory batch fermentation experiments in the presence of the bacteriocin-producing strains Lactobacillus sakei CTC 494, L. curvatus LTH 1174 and Enterococcus faecium RZS C5. A comparison was made with a non-bacteriocin-producing commercial meat starter culture of L. sakei. The L. innocua LMG 13568 population consisted predominantly of bacteriocin-sensitive cells but also contained a small subpopulation of bacteriocin-resistant cells (resistance frequency of 4x10-4). Bacteriocin production by L. sakei CTC 494 and L. curvatus LTH 1174 in a meat simulation medium resulted in the rapid inactivation of sensitive L. innocua LMG 13568 cells, even in the very early stages of bacteriocin production at low bacteriocin activity levels. The inhibition obtained by E. faecium RZS C5 was less pronounced but was better than with a non-bacteriocin-producing starter culture. The harsh conditions typical for a sausage environment (low temperature and pH and high amounts of salt and nitrite) were enough to control the bacteriocin-resistant subpopulation. Hence, bacteriocin-producing starter cultures used under appropriate sausage manufacturing conditions may guarantee a Listeria-free end-product..