An ongoing project is identifying bacteria present in dairy processing environments to assess effects on Listeria monocytogenes.
Teagasc in Ireland and Vienna University of Veterinary Medicine in Austria are collecting samples from dairy processing plants and characterizing microbes with the aim of preventing the presence of harmful pathogens.
The LmRNA project is understanding the response of Listeria monocytogenes to environmental conditions in dairy products. Mock microbial communities are being created in the laboratory to mimic those found in dairy environments. The role of other microorganisms is being studied to determine their effect on L. monocytogenes.
The food processing environment is not sterile and some microorganisms may be present in cheese production. During dairy processing, milk components may adsorb to surfaces, enhancing adhesion and biofilm formation.
Biofilm formation
This three-year project uses macros A genomics approach, where researchers study the interactions between the microbiome in the environment, the most prevalent microbes, and those present in biofilms. Culture-based methods are being used to isolate live bacteria from these environments.
Scientists working on biofilm formation of Listeria monocytogenes in the lab. They use conditions common in the dairy industry, including low temperatures, associated growth media, flow regimes and surface materials such as stainless steel.
Upon entering the food processing environment, bacteria initiate biofilm formation and reversible attachment to surfaces. Over time, these bacteria produce exopolymers (EPS), which can only lose their attachments when subjected to direct mechanical and chemical action.
Over time, biofilms grow and shed bacterial cells. This spreads germs and can be a source of repeated contamination. Biofilm EPS acts as a barrier to the diffusion of antimicrobial agents, thereby protecting enclosed cells. The chemical properties of EPS often deactivate disinfectants and cleaning agents used in the food industry.
Researchers aim to target antimicrobial agents to improve strategies to prevent harmful pathogens from persisting in the dairy industry.
Effects of temperature and salinity on Listeria
Spanish scientists Another study in Soft Pasteurized Milk and Cured Raw Goat’s Milk Cheese looked at Listeria.
Researchers from the Universities of Cordoba and Burgos evaluated the effect of storage temperature and salt concentration on Listeria monocytogenes.
The team analyzed the product at a temperature that reflects the product’s refrigerated temperature of 4 degrees Celsius, and the other was based on storage at room temperature of 22 degrees Celsius (71 degrees Fahrenheit). According to the study published in Food Microbiology, the results show that bacteria survive better at lower storage temperatures.
They found that reducing the salt concentration in the soft cheese did not affect the behavior of the microorganisms.
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