Diversity of spoilage fungi associated with various French dairy products
Résumé
Yeasts and molds are responsible for dairy product spoilage, resulting in significant food waste and economic
losses. Yet, few studies have investigated the diversity of spoilage fungi encountered in dairy products. In the
present study, 175 isolates corresponding to 105 from various spoiled dairy products and 70 originating from
dairy production environments,were identified using sequencing of the ITS region, the partial β-tubulin, calmodulin
and/or EFα genes, and the D1–D2 domain of the 26S rRNA gene for filamentous fungi and yeasts, respectively.
Among the 41 species found in spoiled products, Penicillium commune and Penicillium bialowiezense were the
most common filamentous fungi, representing around 10% each of total isolateswhile Meyerozyma guilliermondii
and Trichosporon asahii were the most common yeasts (4.8% each of total isolates). Several species (e.g. Penicillium
antarcticum, Penicillium salamii and Cladosporium phyllophilum) were identified for the first time in dairy
products or their environment. In addition, numerous species were identified in both spoiled products and
their corresponding dairy production environment suggesting that the latter acts as a primary source of contamination.
Secondly, the resistance to chemical preservatives (sodiumbenzoate, calciumpropionate, potassiumsorbate
and natamycin) of 10 fungal isolates representative of the observed biodiversity was also evaluated.
Independently of the fungal species, natamycin had the lowest minimum inhibitory concentration (expressed
in gramof preservative/l), followed by potassiumsorbate, sodiumbenzoate and calciumpropionate. In the tested
conditions, Cladosporium halotolerans and Didymella pinodella were the most sensitive fungi while Yarrowia
lipolytica and Candida parapsilosis were the most resistant towards the tested preservatives. This study provides
interesting information on the occurrence of fungal contaminants in dairy products and environments thatmay
help developing adequate strategies for fungal spoilage control.