Researchers at Teagasc and the University of Veterinary Medicine in Vienna, Austria, are working to identify bacteria present in dairy processing environments.

The aim of their work is to evaluate the impact of bacteria on the food-borne pathogen listeria monocytogenes (L. monocytogenes).

Food-processing facilities are required to follow regulations to provide food safety assurance. However, the food-processing environment in general is not sterile, Teagasc said.

In some cases the presence of bacteria can be desired, such as in the cheese production environment, where the composition of microorganisms in the immediate surroundings (the microbiome) can contribute to the characteristics of the product.

However, the ‘bacterial community’ in the environment can also harbour pathogens that can compromise food safety.

The project by Teagasc and the Austrian-based researchers will collect samples from dairy environments for evaluation.

The project allows researchers to look at the composition the microbiome in a dairy processing environment; the most prevalent microorganisms present in the sampled environment; and the interaction between microorganisms present in the ‘biofilm’.

Biofilms are the natural state of bacteria in the environment. After entering a food-processing environment, bacteria initiate biofilm formation with a reversible attachment to a surface.

Eventually, these bacteria begin producing ‘exo-polymeric substances’ (EPS) – mainly composed of carbohydrates, proteins and extracellular DNA – which makes the attachment to the surface irreversible.

Given time, biofilms grow and shed bacterial cells and even clumps of cells embedded in EPS. This causes the spread of the bacteria and may become the source of recurrent contamination.

The chemical nature of the EPS often leads to the inactivation of sanitiser and cleaning agents used in the food industry.

In the food-processing environment, biofilms contain multiple species of bacteria. The interaction between these bacteria can either strengthen or weaken the overall biofilm.

Among the bacteria that is being examined by the researchers is L. monocytogenes, a pathogen of significant public health risk due to a relatively high mortality rate, although its infection rate is low.

The project will carryout biofilm formation of L. monocytogenes in a laboratory setting under conditions relevant to the dairy industry, to determine how the presence of other bacteria affect this biofilm.

During the first six months of 2022, the L. monocytogenes pathogen caused at least six recall notices issued by the Food Safety Authority of Ireland (FSAI).