Bacteriophages: A weapon against mixed‐species biofilms in the food processing environment

ABSTRACT Listeria monocytogenes is a ubiquitous, intracellular foodborne pathogen that is responsible for invasive listeriosis. The ability of L. monocytogenes to cause disease has some correlation with the serotypes of a specific lineage group, making the identification of lineage groups important for epidemiological analysis. The development of typing methods to link the strains of L. monocytogenes to an outbreak of listeriosis would help minimize the spread of the disease. The aim of this study was to design a PCR–restriction fragment length polymorphism (RFLP) method to differentiate between the lineage groups of L. monocytogenes. PCR-amplified fragments of the hly gene for 12 serotypes of L. monocytogenes were sequenced, aligned, and analyzed with the BioEdit program, and single nucleotide polymorphisms (SNPs) within regions of this gene were identified. Because of the difficulty in acquiring a serotype 4ab reference strain, this serotype was not included in this study. We tested the specificity and accuracy of the PCR-RFLP method on these L. monocytogenes reference strains and validated the method with 172 L. monocytogenes strains recovered from humans, food, and the food processing environment in 2000 to 2002 and 2008 to 2010 from regions within South Africa. PCR-RFLP analysis applied in this study placed L. monocytogenes serotypes into one of three lineage groups based on the sequence differences and SNPs within each lineage group. The SNPs were conserved in a region where RFLP analysis could be applied for a distinction between L. monocytogenes lineage groups. HIGHLIGHTS

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The microbiome of water and water-associated biofilms in meat processing facilities

10.5194/biofilms9-43 ◽

2020 ◽

Author(s):

Eva M. Wagner ◽

Sarah Thalguter ◽

Kathrin Rychli ◽

Martin Wagner

Keyword(s):

Food Processing ◽

Extracellular Dna ◽

Environmental Research ◽

Meat Processing ◽

Food Contact ◽

Wide Range ◽

Processing Facility ◽

Matrix Components ◽

Biofilm Development ◽

Food Processing Environment

Drinking water represents a reservoir for microorganisms. Microorganisms from water are able to attach to the inner surface of a water hose and nourish themselves by the leaking carbon molecules. Through the interaction of different species a multi-species biofilm can develop. Especially in the food processing environment biofilms in water hoses represent a risk factor. Within the food processing sector water hoses are often used to remove disinfecting agents from freshly cleaned surfaces, after the cleaning and disinfection procedure. When biofilms are located inside these water hoses, cells or cell clusters can detach, subsequently contaminating cleaned food contact surfaces. We checked water hoses as a biofilm hotspot in a meat processing facility by using a flocked swab for biofilm sampling inside the water hose and accessory parts (i.e. nozzle). The bacterial load (culture-based and DNA-based) and the presence of matrix components (carbohydrates, proteins and extracellular DNA) were analysed. &#160; Herby we identified three from six tested water hoses to harbour a biofilm, by being positive for microorganisms and at least two matrix components. This clearly states the need for further understanding of biofilm formation in water hoses. Within the three other hoses, microorganisms could be detected, but no matrix components. We could isolate twelve genera of the water hose associated biofilms using one growth medium (TSA) and two different incubation temperatures (10&#160;&#176;C and 20&#160;&#176;C). There was only on genus that was present within all three water hose biofilms, which was Rhodococcus. Previously this genus was isolated from a shower head (Lee 2013), and is known to catabolise a wide range of organic compounds. This potentially enables the growth in a nutrient poor environment like the water hose providing secondary colonisers launch aid to contribute to the biofilm. The genera Flavobacterium, Microbacterium and Stenotrophomonas were shared among two of the water hose biofilms. Experiments to assess the biofilm forming ability of isolates of these genera using a mono-species static biofilm model indicate that all three species are able to produce matrix and can therefore be regarded as biofilm producers. To date, there is limited information about biofilm development and presence in water hoses, especially in the food processing environment. This first identification of biofilms in water hoses and associated parts emphasizes the need of further research on this topic and detailed monitoring at these sites to prevent recontamination. A currently ongoing microbiome study on the water, the used water hoses, and the water-contacting food contact sites in a meat processing facility will give further details about the biofilm presence and possible transmission of microorganisms encountered there. &#160; References: Lee, Yoonjin. 2013. &#8220;An Evaluation of Microbial and Chemical Contamination Sources Related to the Deterioration of Tap Water Quality in the Household Water Supply System.&#8221; International Journal of Environmental Research and Public Health 10(9):4143&#8211;60.

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