Cadaverine as a Potential Spoilage Indicator in Skin-Packed Beef and Modified-Atmosphere-Packed Beef.

This study investigated cadaverine as a spoilage indicator in commercial beef products stored under conditions favourable for the growth of lactic acid bacteria. Samples included vacuum-skin-packed entrecotes (EB) aged up to 42 days and modified-atmosphere-packed (70% O2 + 30% CO2) minced beef (MB) stored at 5 °C. Two MB product lines were analysed: one stored aerobically two days post-slaughter before mincing and another stored for 14 days in vacuum packaging prior to mincing. Sensory assessment/evaluation and microbial analysis were performed throughout the shelf life of the products and compared to cadaverine levels measured using LC-MS/MS. Cadaverine concentrations in EB reached approximately 40,000 µg/kg on the "best before" date, while remaining below 50 µg/kg in both MB products on the corresponding date. While cadaverine concentrations in EB displayed a consistent increase, suggesting its potential as a spoilage indicator post-ageing, the low concentrations in MB, did not correlate with sensory assessments, revealing its limitations as a universal spoilage marker. In conclusion, it is necessary to conduct product-specific studies to evaluate the applicability of cadaverine as a spoilage indicator for beef products.

Bacterial species diversity of traditionally ripened sheep legs from the Faroe Islands (skerpikjøt).

Skerpikjøt is a traditionally ripened sheep leg product from the Faroe Islands, constituting a relatively underexplored microbial ecosystem. The objective of this study is to achieve a deeper understanding of the microbial composition of this artisanal product. Nine ripened hind legs, obtained from three different producers, were assessed regarding their bacterial communities and contents of biogenic amines, including both surface and core samples. Biogenic amine concentrations were generally low, although one sample had a somewhat elevated concentration of cadaverine. Bacterial diversity was investigated by culture-dependent and culture-independent techniques. Gram-positive catalase-positive cocci (GCC) constituted the most abundant group. Within this group, Staphylococcus equorum was the most prevailing species, followed by Kocuria sp., Mammaliicoccus vitulinus, and Staphylococcus saprophyticus. Lactic acid bacteria prevailed in only one sample and were mainly represented by Latilactobacillus curvatus. Enterobacterial communities were characterised by the prevalence of Serratia proteamaculans. Despite the majority of GCC, Clostridium putrefaciens was the most abundant bacterial species in some core samples. Taken together, the culture-dependent and culture-independent identification methods gave complementary results.

Novel cadaverine non-invasive biosensor technology for the prediction of shelf life of modified atmosphere packed pork cutlets.

Food waste in perishable products calls for the development of cost-efficient and real-time freshness and shelf life assessment tools. The current study evaluated a newly developed cadaverine biosensor for its ability to assess the sensory freshness stage and microbial quality of modified atmosphere packed (MAP) pork cutlets under a realistic supply chain scenario. The experiment compared the cadaverine levels measured by the biosensor to liquid chromatography - tandem mass spectrometry (LC-MS/MS) cadaverine concentrations, and associated these to the shelf life estimation and freshness states determined by sensory and microbial evaluations during an 18-day storage period (5 °C). Results underlined the potential of cadaverine as a freshness biomarker as well as the applicability of the biosensor as a shelf life prediction tool. This is supported by the correlations obtained between sensory odour freshness evaluation and total viable counts with biosensor cadaverine levels for which the r obtained were 0.97 (<0.001) and 0.95 (<0.001), respectively.

Global responses to oxytetracycline treatment in tetracycline-resistant Escherichia coli.

We characterized the global transcriptome of Escherichia coli MG1655:: tetA grown in the presence of ½ MIC (14 mg/L) of OTC, and for comparison WT MG1655 strain grown with 1//2 MIC of OTC (0.25 mg/L OTC). 1646 genes changed expression significantly (FDR > 0.05) in the resistant strain, the majority of which (1246) were also regulated in WT strain. Genes involved in purine synthesis and ribosome structure and function were top-enriched among up-regulated genes, and anaerobic respiration, nitrate metabolism and aromatic amino acid biosynthesis genes among down-regulated genes. Blocking of the purine-synthesis- did not affect resistance phenotypes (MIC and growth rate with OTC), while blocking of protein synthesis using low concentrations of chloramphenicol or gentamicin, lowered MIC towards OTC. Metabolic-modeling, using a novel model for MG1655 and continuous weighing factor that reflected the degree of up or down regulation of genes encoding a reaction, identified 102 metabolic reactions with significant change in flux in MG1655:: tetA when grown in the presence of OTC compared to growth without OTC. These pathways could not have been predicted by simply analyzing functions of the up and down regulated genes, and thus this work has provided a novel method for identification of reactions which are essential in the adaptation to growth in the presence of antimicrobials.

Total and Toxocara canis larval excretory/secretory antigen- and allergen-specific IgE in atopic and non-atopic dogs.

BACKGROUND: Total IgE concentrations are higher in dogs than in humans. Persistent Toxocara canis larval infection is prevalent in dogs and is associated with substantial specific antibody reactions. A correlation, however, between total IgE and T. canis-specific antibody levels in dogs has not been evaluated. OBJECTIVES: To determine the relationship between total IgE, T. canis-specific IgG and IgE, and allergen-specific IgE levels in atopic and non-atopic dogs, and to evaluate possible confounding factors. ANIMALS: Sera of 30 atopic and 30 non-atopic client-owned dogs. METHODS: Total IgE, T. canis-specific antibody and allergen-specific IgE levels were evaluated by ELISA. RESULTS: Total IgE, T. canis-specific antibody and allergen-specific IgE levels were significantly higher in non-atopic compared to atopic dogs. A positive correlation was demonstrated between T. canis-specific IgG and T. canis-specific IgE; T. canis-specific IgG and total IgE; T. canis-specific IgE and total IgE; and allergen-specific IgE and total IgE. No differences were detected on the basis of age, gender, vaccination status; deworming or season between atopic and non-atopic dogs. Previous immunomodulatory treatment and cause of atopy did not influence antibody levels of atopic dogs. CONCLUSIONS: Toxocara canis-specific IgE appears to be a major component of total IgE in dogs. Total and T. canis-specific IgE levels are higher in non-atopic compared to atopic dogs. It is speculated that T. canis infection may have a protective effect against the development of canine atopic dermatitis and/or that elevations in total serum IgE level are often not associated with atopic dermatitis.