Mapping the Kitchen Microbiota in Five European Countries Reveals a Set of Core Bacteria across Countries, Kitchen Surfaces, and Cleaning Utensils

The residential kitchen is often heavily colonized by microbes originating from different sources, including food and human contact. Although a few studies have reported the bacterial composition in cleaning utensils and surface samples there is limited knowledge of the bacterial diversity across different sample types, households, and countries. As part of a large European study, we have identified the microbiota of 302 samples from cleaning utensils (sponges and cloths), kitchen surfaces (sinks, cutting boards, countertops, tap handles, and a pooled sample of other handles) in 74 households across 5 countries (France, Hungary, Norway, Portugal, and Romania). In total, 31 bacterial phyla were identified, with Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria being the most abundant. Despite large variations in households with respect to kitchen standards, kitchen practices, cleaning regimes, and diet and considerable differences in bacterial diversity between samples, eight bacterial genera/families commonly associated with environmental sources were identified in most samples and defined as a core microbiota: Acinetobacter, Pseudomonas, Enhydrobacter, Enterobacteriaceae, Psychrobacter, Chryseobacterium, Bacillus, and Staphylococcus. These genera/families were also among the bacteria with the highest relative abundance across all samples, in addition to Yersiniaceae, Kocuria, Pantoea, and Streptococcus. Taxa associated with potential pathogens and fecal indicators were low in abundance but broadly distributed throughout the households. The microbial composition of surface samples indicated that the microbial composition on kitchen surfaces is more characteristic for the particular country than the object type, while the microbiota of cleaning utensils was similar across countries but differed between types (sponge or cloth).publishedVersio

Metoder for påvisning av Listeria i mat og produksjonsmiljø – Delrapport 1: Hurtigmetoder på markedet

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CO2 packaging increases shelf life through reduction of off-odor production by CO2 tolerant bacteria in addition to growth inhibition of the spoilage bacteriota

Optimized packaging conditions to improve the shelf life of chicken fillets is important to prevent food spoilage and food waste. Anaerobic packaging with CO2 or by vacuum packaging is commonly used to increase the shelf life of skinless chicken fillets, but the literature is inconsistent about the spoilage bacteriota. The aim of this work was to determine which bacterial genera that spoil raw chicken fillets packaged under two common packaging conditions and how the packaging gas itself affects the production of off odors for these genera. The spoilage potential of Pseudomonas, Carnobacterium, Hafnia, Serratia, Brochothrix and Shewanella isolated from spoiled chicken fillets was evaluated. Fresh chicken fillets were inoculated with mono- and multi genera strain cocktails (4 log CFU/cm2) and packaged with 100% N2 or 60% CO2/40% N2, stored at 4 °C, and bacterial numbers, bacteriota, gas in headspace and sensory profiles assessed. Additionally, the effect of CO2 on the production of off-odors from fillets inoculated with similar levels of Shewanella spp. or Brochothrix spp. was determined by both sensory profiling and measuring volatile organic components. All bacterial cocktails grew relatively well in chicken meat packed with 100% N2, while 60% CO2/40% N2 resulted in growth inhibition of all isolates compared to 100% N2. All genera except Serratia and Pseudomonas gave rise to off-odors after 11 days of storage in 100% N2. During storage in 60% CO2/40% N2, only fillets with Carnobacterium spp. and Brochothrix spp. showed significantly higher intensities of off-odors compared to the reference fillets. Shewanella spp. and Brochothrix spp. also exhibited significantly higher intensities of negative odor attributes during storage in 100% N2 compared to 60% CO2/40% N2, at a similar total bacterial count. Thus, CO2 improves shelf life not only by reduction of the growth of CO2 tolerant and sensitive bacteria, but also through inhibition of the production of off-odors.CO2 packaging increases shelf life through reduction of off-odor production by CO2 tolerant bacteria in addition to growth inhibition of the spoilage bacteriotapublishedVersio

Pervasive Listeria monocytogenes is common in the Norwegian food system and is associated with increased prevalence of stress survival and resistance determinants

To investigate the diversity, distribution, persistence, and prevalence of stress survival and resistance genes of Listeria monocytogenes clones dominating in food processing environments in Norway, genome sequences from 769 L. monocytogenes isolates from food industry environments, foods, and raw materials (512 of which were sequenced in the present study) were subjected to whole-genome multilocus sequence typing (wgMLST), single-nucleotide polymorphism (SNP), and comparative genomic analyses. The data set comprised isolates from nine meat and six salmon processing facilities in Norway collected over a period of three decades. The most prevalent clonal complex (CC) was CC121, found in 10 factories, followed by CC7, CC8, and CC9, found in 7 factories each. Overall, 72% of the isolates were classified as persistent, showing 20 or fewer wgMLST allelic differences toward an isolate found in the same factory in a different calendar year. Moreover, over half of the isolates (56%) showed this level of genetic similarity toward an isolate collected from a different food processing facility. These were designated as pervasive strains, defined as clusters with the same level of genetic similarity as persistent strains but isolated from different factories. The prevalence of genetic determinants associated with increased survival in food processing environments, including heavy metal and biocide resistance determinants, stress response genes, and inlA truncation mutations, showed a highly significant increase among pervasive isolates but not among persistent isolates. Furthermore, these genes were significantly more prevalent among the isolates from food processing environments compared to in isolates from natural and rural environments (n = 218) and clinical isolates (n = 111) from NorwaypublishedVersio

Extending the Shelf Life of Atlantic Salmon (Salmo salar) with Sub-Chilled Storage and Modified Atmosphere Packaging in Recyclable Mono-Material Trays

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Deciphering the virulence potential of Listeria monocytogenes in the Norwegian meat and salmon processing industry by combining whole genome sequencing and in vitro data

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Refraining from rights and giving in to personalised control: young unemployed peoples’ experiences and perceptions of public and third sector support in the UK and Norway

In this article, we present an analysis of young unemployed peoples’ perceptions and experiences with public and third sector support in Norway and the UK. Drawing on data generated through qualitative semi-structured interviews, the analysis shows that street level workers’ approaches towards clients are important in understanding(dis)engagement with various employment support systems. Taking a ‘street-level’- perspective as a lens for understanding young, unemployed peoples’ perceptions and experiences, we suggest that their voices as (potential) participants in employment services can contribute a further dimension to perspectives that are more usually focused on workers as performers of politics. The paper highlights the challenges of making employment services responsive to young peoples’ needs and expectations

Dishwashing sponges and brushes: consumer practices and bacterial growth and survival

Sponges are frequently used in kitchens and have been shown to harbor large numbers of bacteria, occasionally also pathogens. Less is known about kitchen brushes regarding usage and presence of bacteria. In the present study, the use of sponges and brushes was studied in a survey among 9966 European consumers in ten countries, and growth and survival of bacteria in sponges and brushes were examined in laboratory experiments. Sponges were the preferred hand-cleaning utensils for washing-up in the majority of countries, while brushes were most frequently used in Denmark and Norway. Consumers mostly change their sponges at regular times, but also sensory cues (looks dirty, smelly, slimy) and usage occurrences such as wiping up meat juices may trigger replacement. Besides cleaning the dishes, over a quarter of the dish brush users also use it to clean a chopping board after soilage from chicken meat juices. The water uptake and drying rate varied considerably, both between different sponges and between brushes and sponges, where brushes dried fastest. Campylobacter survived one day in all sponges and Salmonella more than seven days in two of three types of sponges. In the type of sponge that dried slowest, Salmonella grew on the first day and was always found in higher levels than in the other sponges. Non-pathogenic bacteria grew in the sponges and reached levels around 9 log CFU/sponge. In brushes all types of bacteria died over time. Campylobacter and Salmonella were reduced by more than 2.5 log to below the detection limit after one and three days, respectively. Bacteriota studies revealed a tendency for a dominance by Gram-negative bacteria and a shift to high relative prevalence of Pseudomonas over time in sponges. Both enumeration by agar plating and bacteriota analysis confirmed that the pathogens were in a minority compared to the other bacteria. Treatments of sponges and brushes with chlorine, boiling or in the dishwasher were effective to reduce Salmonella. We conclude that brushes are more hygienic than sponges and that their use should be encouraged. Contaminated sponges or brushes should be replaced or cleaned when they may have been in contact with pathogenic microorganisms, e.g. used on raw food spills. Cleaning of sponges and brushes with chlorine, boiling or dishwasher may be a safe alternative to replacing them with new ones.info:eu-repo/semantics/publishedVersio

Subminimal Inhibitory Concentrations of the Disinfectant Benzalkonium Chloride Select for a Tolerant Subpopulation of Escherichia coli with Inheritable Characteristics

Exposure of Escherichia coli to a subminimal inhibitory concentration (25% below MIC) of benzalkonium chloride (BC), an antimicrobial membrane-active agent commonly used in medical and food-processing environments, resulted in cell death and changes in cell morphology (filamentation). A small subpopulation (1–5% of the initial population) survived and regained similar morphology and growth rate as non-exposed cells. This subpopulation maintained tolerance to BC after serial transfers in medium without BC. To withstand BC during regrowth the cells up regulated a drug efflux associated gene (the acrB gene, member of the AcrAB-TolC efflux system) and changed expression of outer membrane porin genes (ompFW) and several genes involved in protecting the cell from the osmotic- and oxidative stress. Cells pre-exposed to osmotic- and oxidative stress (sodium chloride, salicylic acid and methyl viologen) showed higher tolerance to BC. A control and two selected isolates showing increased BC-tolerance after regrowth in BC was genome sequenced. No common point mutations were found in the BC- isolates but one point mutation in gene rpsA (Ribosomal protein S1) was observed in one of the isolates. The observed tolerance can therefore not solely be explained by the observed point mutation. The results indicate that there are several different mechanisms responsible for the regrowth of a tolerant subpopulation in BC, both BC-specific and general stress responses, and that sub-MIC of BC may select for phenotypic variants in a sensitive E. coli culture

Novel Developmental Analyses Identify Longitudinal Patterns of Early Gut Microbiota that Affect Infant Growth

It is acknowledged that some obesity trajectories are set early in life, and that rapid weight gain in infancy is a risk factor for later development of obesity. Identifying modifiable factors associated with early rapid weight gain is a prerequisite for curtailing the growing worldwide obesity epidemic. Recently, much attention has been given to findings indicating that gut microbiota may play a role in obesity development. We aim at identifying how the development of early gut microbiota is associated with expected infant growth. We developed a novel procedure that allows for the identification of longitudinal gut microbiota patterns (corresponding to the gut ecosystem developing), which are associated with an outcome of interest, while appropriately controlling for the false discovery rate. Our method identified developmental pathways of Staphylococcus species and Escherichia coli that were associated with expected growth, and traditional methods indicated that the detection of Bacteroides species at day 30 was associated with growth. Our method should have wide future applicability for studying gut microbiota, and is particularly important for translational considerations, as it is critical to understand the timing of microbiome transitions prior to attempting to manipulate gut microbiota in early life