JOHN YANG: Finally tonight, from northern Spain, the dying culinary art of making the most expensive cheese in the world.

JOHN YANG (voice-over): In this dank dark cave is some of the world's most prized cheese.

It's where cheesemaker in Carni Bhatta produced the most expensive cheese ever sold at auction, more than $40,000 for a five pound wheel of Cabrales blue cheese.

ENCARNACION BADA, Cheesemaker (through translator): It's expensive.

There's a lot of publicity.

They see you everywhere.

The truth is I've already had people who come because they saw you in Germany or I don't know where, and they come looking for cheese.

JOHN YANG (voice-over): Authentic Cabrales must sit for months in humid limestone caves, absorbing the unique microflora that gives its pungent flavor and aroma.

Bada's family has been aging cheese here for decades.

Her daughter in law, Eva Gutierrez, follows in her footsteps.

She straps a 44 pound load of cheeses on her back and carries it up a steep winding footpath to the aging caves in the mountains of northern Spain's Asturias region.

ENCARNACION BADA (through translator): For us who grew up with it's a way of preserving a culture, a tradition that our grandparents and our parents taught us.

I'm continuing with it, and I hope my son will, too.

At least he'll learn it.

I don't know if he'll make a living from it or not, but he'll learn it.

JOHN YANG (voice-over): Traditionally, making cheese here has been the work of women, but the future is uncertain.

There are now fewer than 20 artisanal cheesemakers.

WOMAN (through translator): What can you do?

You think maybe the world's going to end if you don't make your cheese, but it will go on still.

It's something you say to yourself, and then if I stop, there's no more.

JOHN YANG (voice-over): And that uncertain future could push prices even higher.

JOHN YANG: And that is PBS News Weekend for this Saturday.

I'm John Yang.

For all of my colleagues, thanks for joining us.

See you tomorrow.