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Limburger biodiversity

Two species of yeast, Debaryomyces hansenii and Galactomyces geotrichum, were found. D. hansenii dominated the flora with up to more than 90 % during the different stages of ripening in all three batches investigated, except for the early stage of Batch 2. In this case G. geotrichum dominated. While there was a slight decrease of D. hansenii during the ripening in the first and third batch this was reversed in the second batch. Within D. hansenii two different colony morphology types were found with type 2 occurring as a minority.

The two types were distinguishable by their physiological reaction patterns. Furthermore their FTIR-clusters were clearly separated from each other. Generally, the yeast dendrogram resulting from the FTIR measurements consisted of 9 main clusters which were divided in 27 subclusters. Eighty-three % of the isolates identified as D. hansenii grouped in 6 of 17 subclusters and 66 % of G. geotrichum isolates were arranged in 3 of 10 subclusters. The remaining 17 and 34 %, respectively, appeared to be quite heterogeneous. The 469 yeasts were dereplicated to 43 isolates.

Only two bacteria were found within the isolates of all three batches and both of these are newly described species, Brevibacterium aurantiacum (Gavrish et al. 2004) and Arthrobacter arilaitensis (Irlinger et al. 2004), A single rep-pattern was observed within A. arilaitensis and another one was found for all B. aurantiacum. A minority of isolates (n=5) was identified as Macrococcus sp. Furthermore, some Gram-negatives and bacilli occurred within the Catalase-positive flora. Within the early stages of Batch 1 and 2, B. aurantiacum dominated with up to about 80 %. In addition, Macrococcus sp. or A. arilaitensis occurred. On all the other cheeses of the different batches investigated A. arilaitensis dominanted. The proportion of B. aurantiacum generally ranged between 16 to 30 %.

In the dendrogram depicting the similarity of 423 isolates according to their REP-pattern, 11 clusters became apparent which could be divided into 26 subclusters. 5 isolates were unclustered. Twenty-seven isolates failed to grow after freezing. Subsequently it was found that isolates identified as A. arilaitensis were arranged in 13 different subclusters and, in 4 of these, about 60 % grouped together. A total of 7 clusters belonged to B. aurantiacum, 4 of them contained around 80 % of the isolates. One cluster could be assigned to Macrococcus sp. and the remaining 5 clusters related to sporeformers, Gram-negatives and lactobacilli (LAB). On the basis of the clustering the 423 bacteria were dereplicated down to 43 isolates.

The Limburger cheese investigated showed a low species diversity within the 469 yeast and 423 bacterial strains isolated. The intraspecies diversity of yeast and bacterial isolates reflected a high homogeneity as well. Only a small part of isolates identified as D. hansenii, G. geotrichum and A. arilaitensis, revealed a certain heterogeneity. Generally, an unexpected low biodiversity was observed on the Limburger cheese microorganisms.

Gavrish E.Y., Krauzova V.I., Potekhina N.V., Karasev S.G., Plotnikova E.G., Altyntseva O.V., Korosteleva L.A. and Evtushenko L.I. 2004. Three new species of Brevibacteria, Brevibacterium antiquum sp. nov., Brevibacterium aurantiacum sp. nov., and Brevibacterium permense sp. nov. Microbiology. 73: 176-183.
Irlinger F., Bimet F., Delettre J., Lefevre M. and Grimont P.A.D. 2004. Two new coryneform species isolated from the surface of French cheeses are species of the genus Arthrobacter: Arthrobacter bergerii sp. nov. and Arthrobacter arilaitensis sp. nov. submitted.

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Weihenstephaner Berg 3
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