Researchers have investigated the behavior of Listeria Monocytogenes related to biofilms and how they support the persistence of the pathogen in food processing environments.
A study led by the Austrian competence center for feeding and food quality, safety and innovation (FFOQSI) showed that Listeria monocytogenes can colonize existing biofilms and that it also survives.
Micro-organisms live mainly in communities protected by a self-produced matrix of extracellular polymer substances (EPS). Within these so -called biofilms, microbial cells have changed phenotypes and gene expression patterns. The self -produced common matrix serves as a protective shield, food source and offers room for genetic exchange.
Listeria Monocytogenes can survive for years in the food production environment. Biofilms can offer a niche for long -term survival while protecting against environmental fluctuations and disinfectants.
First study -author, Eva Voglauer from FFOQSI, said: “Our data suggests that Listeria monocytogenes can colonize biofilms in multisecreies, which can increase the chances of survival to cleaning and disinfection in food processing plants and supporting persistence.”
A study published in the magazine Microbiological examinationDiscovered that the bacterial and matrix composition of biofilms is not significantly changed by the presence of Listeria Monocytogenes, indicating that Listeria hidden in the biofilm. This observation could change the view of Listeria Monocytogenes as an active player in the processing environment in a passive surviving and resident of biofilms.
Protection by other bacteria
Scientists investigated the behavior of an isolate of Listeria Monocytogenes in a multisecreies biofilm. This consisted of Pseudomonas Fragi, Brochothrix ThermosFacta and Carnobacterium Maltaromaticum. Within the meat sector, these three possible spoilage bacteria are often isolated. Listeria was able to colonize the multisecrees biofilm within two hours.
The selected Listeria Monocytogenes -Stame with sequence type (ST) 121 was repeatedly insulated from an Austrian meat processing facility. It had colonized the company’s production line for at least one year. Composition of the biofilm community and the matrix and the transcription activity were analyzed.
The growth of the biofilm under food processing of environmental conditions was simulated on a surface of stainless steel, under a low temperature of 10 degrees C (50 degrees F), and with the help of a limited but repeated nutrient supply. After growing a multisecreies biofilm for 24 hours, scientists introduced the Listeria Monocytogenes -Stame and investigated the biofilm composition and gene expression.
“Listeria monocytogenes colonized the multisecreies biofilm and after six hours accounted for 6.4 percent of all biofilm cells. Transcriptomic analysis revealed that 127 genes of Listeria Monocytogenes were signed significantly in comparison with the Inoculum, including genes related to motility, chemotaxis, iron and protein transport, ”said scientists.
The team followed the development of biofilm for six and 24 hours and seven days. Pseudomonas Fragi remained the dominant species, while Listeria Monocytogenes could survive biofilm in multisecreies for 2.4 percent of the total biofilm cells after seven days.
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