Salmonella surveillance on fresh produce and inactivation by high hydrostatic pressure

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2014
Günel, Elif
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In this study, 248 fresh produce samples including tomato, parsley and lettuce (i.e. iceberg and greenleaf lettuce) were collected from supermarkets and local bazaars in Ankara for investigating the presence of Salmonella. Salmonella was detected in 1.2% (3/248) of samples by conventional culturing method with molecular confirmation conducted through polymerase chain reaction (PCR). For further characterization of isolates, serotyping, multilocus sequence typing (MLST) of seven housekeeping genes (aroC, thrA, purE, sucA, hisD, hemD and dnaN) and pulsed-field gel electrophoresis (PFGE) were performed. S. enterica subsp. enterica serotypes Anatum, Charity and Mikawasima were isolated from two parsley samples and one lettuce sample respectively. MLST resulted in 3 sequence types (STs) for our isolates, including one novel ST for serotype Mikawasima. Similarly, PFGE revealed three different XbaI PFGE patterns. The effect of high hydrostatic pressure (HHP) treatment on the viability of Salmonella isolates, artificially inoculated onto fresh produce samples which they were isolated from, was evaluated at 500 MPa for 5 min at 25oC. Salmonella was not detected in any of the HHP treated samples. Shelf life analysis (7 days at 25oC and 4oC) revealed growth only for serotype Anatum which was stored at 25oC, thus indicating the presence of injured cells after HHP treatment. The results of this survey, obtained by the most common subtyping methods (i.e. serotyping, MLST and PFGE) worldwide, contributes to the development of national database in Turkey, which is essential for investigating evolutionary pathways, geographical distribution and genetic diversity of Salmonella strains. In addition, in this study HHP treatment, as an alternative technique to heat processing, represents an applicable tool for control of Salmonella in fresh produce.
Salmonella., Salmonella, High Hydrostatic pressure., Vegetables, Pathogenic bacteria, Pulsed-field gel electrophoresis.
http://etd.lib.metu.edu.tr/upload/12617332/index.pdf
https://hdl.handle.net/11511/23570
Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats
E. Günel, “Salmonella surveillance on fresh produce and inactivation by high hydrostatic pressure,” M.S. - Master of Science, Middle East Technical University, 2014.
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