Yeasts and Molds: Penicillium camemberti

Penicillium camemberti is used in the production of Camembert and Brie cheeses, on which colonies of the fungus form a hard white crust. It is also used as a starter culture for fermented meat products and is often found as a spontaneous colonizer of fermented sausages originating from the mycobiota of the production facility. Its optimum growth temperature range is 20-25°C, with growth being recorded at 5°C but not at 37°C. The fungus is salt tolerant and this coupled with its ability to grow at water activity (a_w) of 0.93 results in it growing on the surface of the cheese during the cheese maturation process. Proteolytic enzymes produced by the fungus play an important role in cheese ripening. The fungus produces the neurotoxic and immunosuppressive compound cyclopiazonic acid (CPA), but CPA is almost exclusively found in the rind and not in the core of the cheese. Penicillium camemberti starter cultures inhibit the undesirable growth of common fungal contaminants of cheese such as Cladosporium herbarum, P. roqueforti, P. caseifulvum, and P. commune. The fungus has also been used to improve the quality of sausage meat, through its superficial inoculation and growth on the sausage surface, thereby eliminating the growth of undesirable naturally occurring mold contaminants.