Lactic acid bacteria inhibit Salmonella bacteria’s disease potential

Monday 28 Apr 14
When lactic acid bacteria are used in salami production to ferment and extend the shelf life of salamis, they also help inhibit Salmonella bacteria’s ability to cause disease. This finding appears from a PhD project at the National Food Institute, Technical University of Denmark, which has studied how Salmonella bacteria are affected by process conditions during the production of salamis.

Salamis, in principle, consist of raw meat, so if pathogenic bacteria - such as Salmonella - are present and survive the manufacturing process, they can make people who eat the salamis sick. Over the years, salamis have been associated with several foodborne disease outbreaks both in Denmark and internationally.

In order for non-heat-treated, fermented salamis to be produced safely, the growth of pathogenic and spoilage bacteria are controlled, e.g. by adding salt and lowering pH.

Starter culture important for food safety

Previous studies have shown that probiotic lactic acid bacteria can reduce various bacteria's ability to cause disease. In her PhD project at the National Food Institute Sidsel Henriksen shows that the same is true of the lactic acid bacteria used by salami manufacturers to ferment and thereby acidify the salamis at the beginning of the production phase.

Sidsel Henriksen's study shows that a lactic acid-containing starter culture not only secretes acid but also bioactive substances, which markedly inhibit the virulence genes that control Salmonella bacteria's ability to make people sick.

Based on the results of the PhD project, it would be interesting to investigate whether these bioactive substances may be used to inhibit or prevent intestinal infections caused by Salmonella.

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See Sidsel Henriksen’s PhD thesis: Impact of food environmental factors related to fermented sausages on Salmonella stress and virulence response (pdf).

Sidsel Henriksen’s PhD study is part of the interagency ConFood project, which is led by the National Food Institute. The project's focus is the control of foodborne infections from lightly preserved meat products through mathematical modeling and effective HACCP-based control programs.