Growth of Listeria Monocytogenes in ready to eat salads at different storage temperatures and valuation of virulence genes expression

BACKGROUND: Vegetables are major components of a healthy and balanced diet. However, 25% of foodborne diseases are linked to the consumption of vegetables. STUDY DESIGN: The aim of this work was to assess the microbiological risks associated with consumption of ready to eat salads (RTE). METHODS: Microbiological challenge tests were carried out for the evaluation of the L. monocytogenes growth potential in RTE salads stored at different temperatures. RESULTS: The results indicate that L.monocytogenes was able to grow (δ ≥ 0.5) in all storage conditions considered at the end of shelf life. In order to evaluate the virulence role of L. monocytogenes, the temperature-dependent transcription of major virulence genes was also investigated by RT-PCR. CONCLUSIONS: The microbiological challenge test allowed us to confirm, as also demonstrated by other authors, that RTE salads are able to support the growth of L. monocytogenes strains (d δ≥ 0.5) stored under different temperatures

Applying the global wealth chain typology to property purchases in the Liverpool and Merseyside Area

The wealth chain is a conceptualisation of extended flows of capital operating across multiple tax jurisdictions in order to extract maximum value from investment locations. To date, such chains have largely been considered in relation to either international tax-avoiding flows of capital to offshore havens or in relation to prime property markets in major metropoles. In this article, we use new data to explain the geographical variations in asset strategies and investment types associated with different types of wealth chain in a historically deprived city region. The data relate to the purchase of real estate in the Liverpool and Merseyside Area (LMA) of the UK by companies from offshore jurisdictions. We use data to empirically model the wealth-chain concept. We compare the results from our empirically derived model with the key theoretical propositions regarding such chains. Our results confirm the actions of identifiable types of wealth chain. By geographical distribution, the specific asset strategy that dominates suggests that wealth-chain offshore investors in Liverpool’s real estate are primarily motivated by their desire to protect their identities and their assets. In the literature on the subject, these are much sought after attributes of money launderers and others involved in illicit wealth accumulation. In money terms, the dominant asset strategy is situated in a much smaller geographical space in and around the city centre. In the literature, this type of wealth chain is associated with the multinational corporations who are, theoretically, the main source of innovation in wealth-chain operations

Molecular methods for the rapid detection of bacterial food pathogens

The polymerase chain reaction (PCR) is considered the most reliable method for the rapid identification of Listeria monocytogenes in foods, when a response within 24 h is needed; however, with this method false reactions caused by the abundant DNA present in the food extract are possible. DNA probes are less sensitive than PCR, but they can be very useful for confirming the doubtful cases obtained with the PCR or for the identification of isolated and purified strains. The use of PCR in combination with a specific DNA probe can be the best method for obtaining a rapid, sensitive and reliable identification of Listeria within a working day or less

THE SELECTIVE STAINING MECHANISM OF PHOSPHATASE-PRODUCING COLONIES IN THE DIPHOSPHATEPHENOLPHTALEIN-METHYL GREEN METHOD FOR THE DETECTION OF BACTERIAL PHOSPHATASE ACTIVITY

The aim of this study was to explain, in a novel method for the testing of bacterial phosphatase activity (MGP), the mechanism by which, in the presence of a phosphatase substrate and a stain, the phosphatase positive colonies become intensely pigmented while the others remain unstained (Satta et al., 1979). The experiments here described indicate that the products of the phosphatase reaction form, with the stains, high pigmented insoluble complexes that precipitate at the site where the reaction has occurred. Since, in most bacteria, phosphatase are membrane bound, in the presence of phosphatase substrates and stains, intensely stained precipitates are formed on his bacterial component.