Fermented Foods Microbiome

Forschungsprogramme Mikrobielle Biodiversitaet Lebensmittel
The Lactobacillus casei pan-genome. A hypothesis says that bacteria distribute all of their genes over many strains (left-hand figure) and that genes are thus gained and lost over generations. The sequencing of different L. casei strains of the Agroscope Strain Collection has repeatedly brought new genes to light (right-hand figure). The dashed line shows the sum of all genes (the pan-genome) identified with each further genome sequencing of an L. casei strain. The solid line represents the number of genes present in all strains. The studies confirm that the sum of all genes of this species is indeed distributed across individual strains. The importance of this genomic diversity in lactic acid bacteria for fermented foods is examined in detail in the present ARP.

The ‘Fermented Foods Microbiome' work package investigates the biodiversity represented in the Agroscope Strains Collection (Liebefeld, Wädenswil), analyses the biodiversity of the ‘raw-milk cheeses' ecosystem, and studies the microbial and biochemical processes of cheese ripening as well as the interactions of the various bacteria species within the different types of raw-milk cheeses. The aim is to be able to select bacteria for the manufacture of fermented milk products so that milk processers can produce high-quality raw-milk cheeses at a lower cost and with less faulty fermentation, and consumers can be offered safe fermented dairy products with a variety of flavours. In cheese production, for example, it was shown that the use of a cheese smear composed of a large number of microorganisms with an antagonistic effect on undesired bacteria led to an improvement in food safety (suppression of listeria) [1].

[1] Roth, E.: Control of Listeria contamination on the surface of semi-hard cheeses by natural smear ecosystems and protective cultures, ETH  Dissertation No. 18644, Zurich 2009.


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