, 2008; De Baets et al., 2009). FAFLP is a high-resolution and reproducible
methodology that assesses the genome for genetic polymorphism between strains of the same and different species. The method identifies polymorphisms resulting in point mutations within the restriction-site targeted by the endonucleases used for the analysis. This may result in either loss or gain of fragments, or insertion or deletion between the two endonuclease restriction-priming sites, thus resulting in polymorphic fragments of varying sizes. A strain-characteristic FAFLP profile varying in the number and sizes of the fragments is obtained. A recent paper by Desai et al. (2006) examined the genetic stability of bacterial strains preserved by two different methods, lenticulation and freeze-drying, using Enzalutamide cost FAFLP. No detectable genetic changes were found between the two approaches to preservation, or as a result of storage of isolates over a 5-year period. However, to our knowledge, there have been no studies evaluating the potential introduction of random mutations
or chromosomal rearrangements as a result of repeated subcultures of the reference cultures used in food microbiology laboratories. In Torin 1 purchase this study, we examined the genetic stability of the working cultures (control strains will henceforth be referred to as working cultures) obtained from different food laboratories using standardized FAFLP analysis. The resultant FAFLP profiles were compared with those obtained from the relevant reference NCTC strains, which were freeze-dried in evacuated glass ampoules or preserved on LENTICULE discs. Eight food examination
laboratories accredited by the United Kingdom Accreditation Service (UKAS) for a wide range of food examination procedures agreed to participate in this study. Each laboratory was anonymized and designated a number Calpain (Lab #1 to Lab #8; Table 1). All the laboratories had purchased the control strains for their reference stocks from NCTC as freeze-dried cultures in glass ampoules. Each laboratory submitted their working culture that had been prepared from their reference stock. Working cultures of four different bacterial species were submitted by each of the eight laboratories. Corresponding ampoules containing freeze-dried cultures of the four strains were obtained directly from NCTC to be used as reference strains for the study. The bacterial cultures included Salmonella Nottingham (NCTC 7832), Listeria monocytogenes (NCTC 11994), Staphylococcus aureus (NCTC 6571) and Bacillus cereus (NCTC 7464) (Table 1), and a total of 50 isolates were examined in this study. Individual laboratories submitted isolates from their current working culture by inoculating nutrient agar slopes and incubating the slopes overnight at 37 °C. The slopes were sent to Microbiology Services Colindale at the Health Protection Agency (HPA) for examination.
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