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Identification of the yeasts and bacteria on the surface of Reblochon

Three batches of Reblochon cheese were produced in different farmhouses without addition of yeast or surface microflora starter. The predominance of Galactomyces Geotrichum on the surface of Reblochon cheese was found. Nevertheless, its intraspecies diversity was low since only three different clusters were obtained by similarity analysis of the FTIR spectra. Galactomyces Geotrichum appeared as a yeast well adapted to the biotope of this cheese.

The current high occurrence of kluyveromyces lactis and its high diversity was not observed in the previous study on Reblochon cheese by Bärtshi et al., (1994). They rarely isolated this species (about 1%) in the five cheese factories investigates. Conversely, Debaryomyces hansenii was very less isolated than previously and only on cheeses from farmhouse. That is surprising because this species is generally recognised as a dominant species on numerous types of cheeses made in many countries on mould cheese as well as on smeared cheese. Toruloaspora delbrueckii was observed at the same low level in the two studies on Reblochon cheese. Other yeast species found here, especially Saccharomyces servazzi and Saccharomyces unisporus were not isolated in the previous work on Reblochon cheese. Satunispora was only found in Reblochon cheese made in farmhouse. The species was delineated using biomolecular tools. Finally, yeast flora found on Reblochon cheese in the course of years between factories, at least in farmhouse, have shown an original feature and high diversity.

The microflora of Reblochon cheeses seems to be composed almost exclusively by coryneform bacteria. For the Arthrobacter genus, only A. arilaitensis was found at the end of ripening on cheese made in the three farmhouses. In the Brevibacterium linens group, two species were found: B. linens and much more abundant B. aurantiacum. Corynebacterium is the dominant genus since about half of identified bacterial isolates belong to this genus. C. variabile was the main species encountered on cheese whatever stage of repening or farmhouses.

Mycetocola is a new genus of the Microbacterium family. To our knowledge it is the first time that this genus is isolated from cheese.

The last genus which have shown a noticeable abundance was Microbacterium especially M. gubbeenense, found mostly at the end of ripening according to its sensitivity to low pH. Others genera were sporadically isolated such as Brachybacterium, Rothia, Staphylococcus.

Biodiversity of yeasts and bacteria on the surface of Reblochon cheese appeared relatively large in comparison to others smear cheeses because commercial culture was inoculated on studied cheeses.

The diversity of microflora found on this traditional cheese is involved, at least partially, in the sensorial diversity of Reblochon cheese and likely contributes to the production of non-uniform food.

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