Some secrets of cheese revealed with genome study

Makers of Roquefort and Camembert could benefit from a new genetic study of 14 fungal species found in cheeses, French researchers said Thursday.

But the study published in the journal Current Biology also raises questions about food safety due to the transfer of genes among Penicillium fungi, which are key to the making of soft cheeses.

"We were able to identify genes that are directly involved in the adaptation to cheese in Penicillium, opening the way for strain improvement, in particular for obtaining fast-growing strains," said co-author Antoine Branca of L'Universite Paris-Sud.

Scientists found an important role for the transfer of genes among the fungi, which allows them to adapt to the fermentation process that produces cheese.

"Cheeses are an emblematic French food, and there is a great diversity of cheese-making fungal species and strains, used for different kinds of cheeses, and thus selected for different traits," said co-author Tatiana Giraud.

But the ease with which genes are exchanged among species also suggests that fungi which spoil food or produce toxins could easily find their way into growing in cheeses.

"Our findings, on the other hand, raise concerns about food safety because they suggest that the co-occurrence of different fungal species in the same food product allows genes to be transferred from one species to the other frequently, as it occurred multiple times, for multiple genomic regions," said Branca.

And scientists still don't know everything about cheese fungi.

In particular, they do not know where to find the blue fungus Penicillium roqueforti, contained in Roquefort and blue cheeses, in nature.

Researchers said the fungus has been found on decaying wood, but is rarely seen in natural settings.

But the fungus maintains considerable genetic diversity, suggesting that it must exist somewhere in relatively large populations.

"If you find a wild blue mold growing outdoors, please let us know," Branca said.