Saccharomyces Pastorianus v/s Saccharomyces cerevisiae

I want to brew a lager that requires Saccharomyces Pastorianus and a homebrew shop offered me Saflager W34/70. I read online that Saccharomyces carlsbergensis, which is the old name for what is known as Saccharomyces pastorianus, is a hybrid of either Saccharomyces bayanus or Saccharomyces eubayanus, and Saccharomyces cerevisiae.

When I search online for Saflager W 34/70, I found that it is just pure Saccharomyces cerevisiae.

I want to brew a beer called Foggy Bottom Lager by Old Heurich, which specifically calls for Saccharomyces pastorianus. Because I quite like the taste, I want to get the exact yeast.

Should I buy the Saflager W 34/70 or keep looking for the S. Pastorianus?

Thank you!

I've never heard of a yeast specifically marketed as S. pastorianus, even though that's what all lager yeasts probably are.

Even within the S. pastorianus there are lots of different strains, so without knowing more about that beer you want to make, it's impossible to find a yeast that's an exact match.

This would be a good question to post in the "yeast and fermentation" subforum on here.

It's an Oktoberfest-style beer if I am not mistaken. I'd start your quest with an Oktoberfest yeast, like WLP 820.

from what i could find thats just a broad name for lager yeast. if its an oktoberfest beer, then i would go with what arcaneXor is suggesting.

W-34/70 is most definitely a lager yeast, and possibly the best dry lager yeast available to homebrewers, but it's NOT my favorite. It and its close equivalents in liquid form seem to me to be slow, non-flocculent, and diacetyl-prone, especially compared to Wyeast 2308.

34/70 has some advantage in attenuation, though, if that's important to you.