Wooden shelves were first changed after one week and every three weeks thereafter. The pH of the cheese surface was periodically measured in situ using a flat membrane electrode (InLab® Surface, Mettler-Toledo, Greifensee, Switzerland). Microbial analyses of cheese surface during ripening experiments Approximately 25 cm2 of cheese surface were scraped off using sterile cotton rolls (IVF Hartmann, Neuhausen,

Switzerland) and aseptically transferred into a stomacher bag. Each sample was suspended in 25 ml pre-heated (45°C) peptone water, composed of 1% (w/v) casein peptone, 0.5% (w/v) NaCl and 2% (w/v) tri-sodium click here citrate dehydrate, all from Merck (Dietikon, Switzerland), and homogenized for 4 min using a Stomacher (Silver Masticator; IUL Instruments GmbH, Königswinter, Germany). Selleck RAD001 selleck compound 1 ml of this solution was submitted to total DNA extraction for TTGE as described above. Serial dilutions in 0.9% (w/v) NaCl were prepared and plated on TGYA, PY agar and Palcam agar. At the end of ripening, 10 g of smear were harvested and tested for the presence of Listeria

using an enrichment procedure as described above. Acknowledgements This work was supported by the Research Station Agroscope Liebefeld-Posieux ALP, Bern, Switzerland. We thank Daniel Goy for sharing expertise in cheese ripening. We also thank Hélène Berthoud and Monika Haueter for excellent assistance with sequencing and DNA extraction protocols. References 1. Bockelmann W, Hoppe-Seyler T: The surface flora of bacterial smear-ripened cheeses from cow’s and goat’s milk. Int Dairy J 2001, 11:307–314.CrossRef 2. Mounier J, Gelsomino R, Goerges S, Vancanneyt M, Vandemeulebroecke K, Hoste B, Scherer S, Swings J, Fitzgerald GF, Cogan TM: Surface microflora of four smear-ripened cheeses. Appl Environ Microbiol 2005, 71:6489–6500.PubMedCrossRef 3. Wenning M, Theilmann V, Scherer S: Rapid analysis of two food-borne microbial communities at the species level by Fourier-transform infrared microspectroscopy.

Environ Microbiol 2006, 8:848–857.PubMedCrossRef 4. Ogier JC, Lafarge V, Girard V, Rault A, Maladen V, Gruss A, Leveau JY, Delacroix-Buchet A: Molecular fingerprinting of dairy microbial ecosystems by use Unoprostone of temporal temperature and denaturing gradient gel electrophoresis. Appl Environ Microbiol 2004, 70:5628–5643.PubMedCrossRef 5. Feurer C, Irlinger F, Spinnler HE, Glaser P, Vallaeys T: Assessment of the rind microbial diversity in a farmhouse-produced vs a pasteurized industrially produced soft red-smear cheese using both cultivation and rDNA-based methods. J Appl Microbiol 2004, 97:546–556.PubMedCrossRef 6. Rademaker JLW, Peinhopf M, Rijnen L, Bockelmann W, Noordman WH: The surface microflora dynamics of bacterial smear-ripened Tilsit cheese determined by T-RFLP DNA population fingerprint analysis. Int Dairy J 2005, 15:785–794.CrossRef 7. Bockelmann W: Development of defined surface starter cultures for the ripening of smear cheeses. Int Dairy J 2002, 12:123–131.