For lager lovers worldwide, it is probably the most highly prized micro-organism in the world.

But the identity of the yeast that made cold refreshing beer possible has been a long-standing mystery.

Scientists believe they have unmasked the microbe behind the creation of lager. Credit:Mayu Kanamori

Now scientists believe they have unmasked the microbe - a stowaway that sailed to Europe from the New World 500 years ago.

The yeast ended up in the caves and monasteries where beer was brewed in Bavaria. There, it crossed with a distant relative, a yeast used for millennia to make bread and ferment wine and ale. The rest was history.