Ungrateful yeast

Sacharomyces cerevisiae cells in DIC microscop...

Yeast cells reproducing. Note the buds forming on two of the cells. (Image via Wikipedia)

It’s been more than 37 hours since we pitched with Wyeast 2007 (Pilsner Lager) yeast into the cooled wort of the house pale ale and there is still no indication of fermentation. Wyeast 2007 comes in a “smack-pack.” The package had expanded, so the yeast were active at 6pm on Sunday when they were pitched into the 62F wort.

At a specific gravity of 1.050, this beer isn’t a high gravity beer (1.060 and above), so a lack of aeration should not be an issue. Could it?

Kräusen on top of wort pitched with pilsner lager yeast.

Update: A foamy head of Kräusen has appeared on the top of the wort some 42 hours after the yeast pitch.