Journal Article


R P Ross
C Hill
P D Cotter
B Collins



food preservatives drug effects nisin food contamination microbial viability cheese pharmacology anti bacterial agents drug resistance bacterial mutation prevention control genetics microbiology listeria monocytogenes

The impact of nisin on sensitive and resistant mutants of Listeria monocytogenes in cottage cheese. (2011)

Abstract Listeria monocytogenes ΔgadD1 and ΔlisK mutants display enhanced and reduced sensitivity, respectively, to the food preservative nisin in laboratory media. However, the behaviour of these strains in a nisin-containing food has not been assessed. Here we use cottage cheese as a model food to address this issue. Antibiotic-resistant forms of the wild-type and mutant strains were employed to investigate the behaviour of multiple strains in a single food sample, thereby eliminating the problem of intersample variation. Using this approach, it was established that percentage survival of the ΔlisK mutant was greater than the parent strain in the absence of nisin and that this relative difference became even more dramatic in cottage cheese supplemented with nisin. The numbers of the ΔgadD1 mutant decreased more rapidly than the parent in cottage cheese without nisin, but surprisingly this trend was reversed in nisin-supplemented cheese. Upon the addition of 10 mmol l(-1) monosodium glutamate, a substrate for the glutamate decarboxylase (GAD) system, the wild-type LO28 strain regained its relative advantage over ΔgadD1. Care needs to be taken when predicting the behaviour of mutants of L. monocytogenes with altered resistance to nisin in food as experiments in laboratory media are not always a good indicator of how the strains will behave in such food environments. This study further emphasizes the importance of utilizing food matrices to confirm observations made using laboratory media.
Collections Ireland -> University College Cork -> PubMed

Full list of authors on original publication

R P Ross, C Hill, P D Cotter, B Collins

Experts in our system

R Paul Ross
Total Publications: 441
Colin Hill
University College Cork
Total Publications: 351
Paul D. Cotter
Total Publications: 253
Barry Collins
University College Cork
Total Publications: 11