Why are some aged and ripened cheeses so delicious?
Can you imagine doing research in a cheese cave for 8 years? What a temptation! đ
"Fungi play vital roles in food production and ecosystems, but we rarely observe their evolution in real time. Louw et al. followed a population of the mold Penicillium solitum growing in a Vermont cheese cave over 8 years. They observed a striking change from green to white colonies caused by mutations in the melanin-producing gene alb1.
These white strains made less pigment and fewer spores but grew better than green ones in the dark cave environment. These findings reveal how fungi can quickly adapt to human-made habitats with relaxed selection for traits such as pigmentation. Such local adaptation represents an early stage of fungal domestication and could inspire the development of new molds for cheese and fermented foods."
From the highlights and abstract:
"Highlights
• A Penicillium solitum population has shifted from green to white in a cheese cave
• Multiple mutations in a melanin biosynthesis gene (alb1) are found in white strains
• White P. solitum strains outcompete green strains, but only in the dark
• This local adaptation may be part of a fungal domestication process
Summary
Previous comparative and experimental evolution studies have suggested how fungi may rapidly adapt to new environments, but direct observation of in situ selection in fungal populations is rare due to challenges with tracking populations over human time scales.
We monitored a population of Penicillium solitum over eight years in a cheese cave and documented a phenotypic shift from predominantly green to white strains.
Diverse mutations in the alb1 gene, which encodes the first protein in the dihydroxynaphthalene (DHN)-melanin biosynthesis pathway, explained the green-to-white shift.
A similar phenotypic shift was recapitulated with an alb1 knockout and experimental evolution in laboratory populations.
The most common genetic disruption of the alb1 genomic region was caused by putative transposable element insertions upstream of the gene. White strains had substantial downregulation in global transcription, with genetically distinct white strains possessing divergent shifts in the expression of different biological processes.
White strains outcompeted green strains in co-culture, but this competitive advantage was only observed in the absence of light.
Our results illustrate how fermented food production by humans provides opportunities for relaxed selection of key fungal traits over short time scales. The local adaptation we observed may be part of a domestication process that could provide opportunities to generate new strains for innovation in fermented food production."
Graphical abstract
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