These are experimental cheeses that are not for sale (yet!). But this science/craft collaboration highlights how the unintentional domestication in the Cellars at Jasper Hill Farm could lead to innovation in cheese production.

Stay tuned for more fun cheese microbial ecology and evolution! 🧀

I am also thrilled that our work has inspired the amazing team at Jasper Hill Farm to make new cheeses (bloomy rind cheese in top of the photo) with their locally-adapted Penicillium solitum isolates. This is different from the French strains of Penicillium camemberti that are typically used.

Nicolas also collected very cool data showing that white mutants have a fitness advantage over the green Penicillium solitum. But this advantage is only in the dark (with all lights off). We suspect that the dark cheese cave environment leads to relaxed selection for melanin production.

Super grateful for the amazing team in the @kellerlab.bsky.social who helped us make alb1 knockouts that clearly demonstrated how this gene controls pigmentation in Penicillium solitum.

There is a lot in the paper, and too much to unpack here (read it!). But my favorite part of the story is that transposable elements that insert just upstream of alb1 are likely causing a lot of the green --> white phenotypic shifts.

And so began the highly creative and integrative PhD project by @nicolasleonlouw.bsky.social to understand if/how Penicillium solitum was evolving in this cheese cave. The frozen samples from 2016 from the wedding proposal trip were an essential microbial time capsule for this work.

We used images from social media and other sources to piece together a timeline of the Bayley Hazen Blue green-to-white transition from ~2014 to 2024.

At the same time, we had been noticing (with lots of help from the amazing team of cheesemakers and affineurs!) that in the Jasper Hill cheese caves, the rinds of Bayley Hazen Blue were turning white!

Alb1 is the first step in melanin biosynthesis for many fungi. When you alter or completely inactivate the alb1 gene in many fungi, you get white mutants, as Paul Dyer's group has previously demonstrated with Penicillium roqueforti. www.nature.com/articles/s41...

A bright undergrad (Jackson Larlee) in a lab course that Nicolas and I were teaching noticed that in some white strains, there were mutations in a polyketide synthase gene. The genome was poorly annotated (at the time), but Jackson figured out that the gene was like alb1.

In some cases when you passaged the green Penicillium solitum on cheese curd agar in the lab, it would change from green to white over very short periods of time.

Flash forward to 2023 when @nicolasleonlouw.bsky.social was doing some experimental evolution in the lab with the fungus Penicillium solitum. It was isolated from the rind of Bayley Hazen Blue (was responsible for the green rind in 2016) and the fungus was doing some weird trait switching.

Rachel said YES to Charlie's marriage proposal. And we collected a bunch of samples from the rinds of Bayley Hazen Blue cheese. At the time, the rinds of the cheese were bright green. I put the 2016 green rind samples in the -80 freezer and never tossed them out...

In 2016, I was part of a scheme to get Rachel Dutton (my post-doc advisor) up to the cheese caves at Jasper Hill Farm in Vermont. Her boyfriend (Charlie Kalish) wanted to propose to her where they met. I told Rachel we had important cheese rind samples to collect. She went along with it!