Listeria monocytogenes is a potentially lethal foodborne pathogen commonly found in the environment. European Union hygiene legislation places responsibility for safety on primary production facilities, including farms, as part of a policy to introduce traceability throughout the food chain. This study aimed to determine the occurrence of L. monocytogenes in the Irish dairy farm environment and in particular the milking facility. Two hundred ninety-eight environmental samples were collected from 16 farms in the southern region of Ireland. A number of farms within the group supply raw milk to the unpasteurized milk cheese industry. The samples taken included cow feces, milk, silage, soil, water, etc. Samples were enriched in Listeria enrichment broth and incubated for 48 h, followed by plating on chromogenic agar Listeria Ottavani & Agosti and further incubation of the plates for 24 to 48 h. Presumptive L. monocytogenes isolates were purified and confirmed by PCR targeting the hly gene. Overall, 19% of the samples (57 of 298) were positive for L. monocytogenes. These were serotyped using conventional and PCR methods; serotypes 1/2a, 1/2b, and 4b made up 78% of the typeable isolates. A correlation was found between the level of hygiene standards on the farm and the occurrence of L. monocytogenes. There was little difference in the occurrence of L. monocytogenes between farms supplying milk to the unpasteurized milk cheese industry and those supplying milk for processing. This study demonstrates the prevalence of L. monocytogenes in the dairy farm environment and the need for good hygiene practices to prevent its entry into the food chain.

No abstract

This paper describes the quantitative measurement, by in situ synchrotron X-ray diffraction (S-XRD) and subsequent Rietveld-based quantitative phase analysis and thickness calculations, of the evolution of the PbO2 and PbSO4 surface layers formed on a pure lead anode under simulated copper electrowinning conditions in a 1.6 M H2SO4 electrolyte at 318 K. This is the first report of a truly in situ S-XRD study of the surface layer evolution on a Pb substrate under cycles of galvanostatic and power interruption conditions, of key interest to the mining, solvent extraction and lead acid battery communities. The design of a novel reflection geometry electrochemical flow cell is also described. The in situ S-XRD results show that β-PbO2 forms immediately on the anode under galvanostatic conditions, and undergoes continued growth until power interruption where it transforms to PbSO4. The kinetics of the β-PbO2 to PbSO4 conversion decrease as the number of cycles increases, whilst the amount of residual PbO2 increases with the number of cycles due to incomplete conversion to PbSO4. Conversely, complete transformation of PbSO4 to β-PbO2 was observed in each cycle. The results of layer thickness calculations demonstrate a significant volume change upon PbSO4 to β-PbO2 transformation.

No abstract

No abstract