E-MUSE

The action of yeasts,  moulds and ripening bacteria, which can grow parallel orsequentially in the cheese curd, results in the production of flavour compounds. These flavour compounds are produced when there is an accumulation of metabolites due to a   slow-down of the central metabolism when substrates, cofactors,   oxygen or metals become unavailable.   Metals are involved in all biological processes,  as cofactors of many enzymes. Iron in cheese is linked to various components such as proteins, carbohydrate or citrate. Milk lactoferrin is a mammalian protein belonging to the transferrin family able to bind two ferric ions. The high stability constant of the iron-protein complex confers to lactoferrin anti-microbial activity leading to low iron availability for microorganisms in the curd. Species competition or mutualism depending on iron bioavailability can be one factor responsible for the structuring of the surface ripening microorganisms which are strict aerobe and need iron for their electron transport chain. Central carbon metabolism,   amino acid and fatty acid metabolisms linked to iron metabolism are key metabolic processes involved in the production of flavour in fermented products.    The effect of iron on the metabolism of ripening microorganisms,   alone or in consortia,   will be studied in controlled conditions. Growth parameters will be identified, a predictive growth model will be done to better anticipate complex ecosystem understanding. Metabolomics data will be collected and analysed. The results will be used to constrain a microbial community genome-scale metabolic model by   ESR1   (VUA).   One microorganism will be selected for further studies by the   ESR.   Physiological and transcriptomics data will be collected and a genome-scaled model will be developed thanks to planned secondments.