A recent domestication event in Penicillium biforme, independent of the emblematic cheese mold P. camemberti

Domestication of molds for cheese production has repeatedly shaped Penicillium fungi, most notably giving rise to the emblematic P. camemberti lineage, derived from P. biforme. Here, we identified a new P. biforme lineage, named cheesy, likely selected from P. biforme for food fermentation, including cheese and sausage production. This lineage exhibits evidence of a severe bottleneck, with little nucleotide polymorphism and a single mating type. The cheesy lineage has evolved advantageous traits for cheesemaking: compared to other P. biforme strains and its wild relative P. fuscoglaucum, it displays faster growth on cheese, galactose and lactose media, higher sporulation and germination rates on cheese, elevated lipolytic activity, enhanced inhibition capacities, and produced specific volatile organic compounds. Additionally, P. camemberti and P. biforme cheesy differ in their content of Starship mobile elements, acquired through horizontal transfers. These elements carry cargo genes potentially relevant for adaptation to cheese. Notably, the cheesy lineage has acquired a 20 kb Starship element (Rattus), nested within a much larger 160 kb Starship (Bilge), and carrying cargo genes with predicted functions involved in antagonistic interactions among micro-organisms. SignificanceO_LIWe identified a new Penicillium biforme lineage, named cheesy, which was likely selected from P. biforme for food fermentation (cheese and sausage), genetically and phenotypically different from the emblematic P. camemberti lineage. This lineage suffered from a severe bottleneck, displaying very little nucleotide polymorphism and a single mating type. C_LIO_LIThis newly identified lineage has evolved advantageous traits for cheesemaking; compared to other P. biforme strains and its wild relative P. fuscoglaucum, it displayed faster growth on cheese, galactose and lactose media, higher sporulation and germination rates on cheese, higher lipolytic activity, better inhibition capacities and specific volatile organic compounds. C_LIO_LIPenicillium camemberti and P. biforme cheesy also differed by their content in Starship mobile elements, acquired through horizontal transfers, and carrying cargo genes potentially relevant for adaptation to cheese. C_LIO_LINotably, the cheesy lineage has acquired a specific 20 kb Starship nested within a much larger 160 kb Starship, and likely involved in antagonistic interactions. C_LI