Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Yeast culture collection

A database for yeasts was constructed as an Excel file. It contains data from FTIR measurements as well as results of phenotypic investigations of representatives selected from the dereplicated strains from the different cheeses. The biochemical and compositional analyses of the different cheeses are also included in the database. A completing dendrogram of representatives of all five cheeses (Gubbeen: 42 and 45, Limburger: 43, Livarot: 46, Reblochon: 51 and Tilsit: 76) was prepared to study the relationships between the flora of the different smears. There was only one cluster which contained yeast spectra from different cheeses, i.e., Livarot, Tilsit and Limburger.

Most often the clusters consisted of spectra from one cheese or from two different cheeses. This indicates a certain individuality of each cheese`s yeast flora. A similarity between yeast spectra from Livarot and Tilsit cheese were noticed. Six common clusters existed, three assigned to G. geotrichum, two to Yarrowia lipolytica and one to Candida catenulata. Usually only one or two common clusters of spectra from yeasts from two different cheeses were formed. Interestingly, the yeast spectra from the two French cheeses showed only one common cluster existed.

In representatives from Tilsit and Reblochon a high number of spectra, 47 and 29, respectively, was unclustered. A reason for this might be the generally high diversity within these isolates. This resulted in smaller clusters and a lot of unclustered spectra in the cheese specific dendrograms, which were the basis for dereplication. Contrary to this were the results obtained for Limburger cheese. Since these isolates appeared to be very homogeneous the clusters in the individual Limburger dendrogram which was used for dereplication contained a lot of spectra and therefore several representatives were chosen from each cluster.

The number of representatives, which were taken from one cluster increased by cluster size. On the basis of this it is explainable that only a low number of unclustered spectra from Limburger yeasts occurred in the complete dendrogram. Clusters in that completing dendrogram which only contained spectra from Livarot strains were mainly assigned to Galactomyces geotrichum. Strains from this species on Livarot cheese showed a high homogeneity. In spectra from Gubbeen yeasts a lot of separate clusters were formed in the complete dendrogram. However, also a lot of unclustered spectra were noticed. The unclustered spectra most often belonged to yeasts isolated from the first three batches of Gubbeen cheese in which a higher diversity appeared. The dereplicated yeast strains of all five cheeses are stored as glycerol stocks at 80°C. Representatives of them will be freeze-dried and deposited in the Weihenstephan Yeast Collection.

Reported by

TECHNICAL UNIVERSITY OF MUNICH
Weihenstephaner Berg 3
85350 FREISING
Germany
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