Bottle dregs are a very interesting and economical way to get your hands on some yeast. I went to my local beer store and bought some bottles with hopefully interesting bugs inside.
Check that your bottles are as fresh as possible and that they were kept cool.
I don’t use Erlenmeyer flasks because its impossible to keep them sterile. Old jam glasses with a screw on lid do the job much better with a slight modification, see my yeast starter post.
The mixture for my starter is a 1:10 ratio of dried malt extract and water. This creates a wort of about 1.035 gravity. I do not add any hops.
The half filled mason jars were then sterilized in a pressure cooker @ 15 psi for about 15 minutes.
When i was ready to drink some beer, i poured all but 1 cm in a glass, put that away, swirled the sediments up and added it to the jar with the starter Wort.
The starter was then put away @ about 18 – 22C. After 2 or 3 days, you should see signs of fermentation. You can then step up your starter as needed.
This is an incomplete list of yeast i tried harvesting from the following bottles. This is no second hand information, i have tried culturing every yeast in the list.
Boon Oude Geuze
Produced a fruity sour taste. Probably a mixture of brett, sacc and lacto. I used this as additional bug for many of my sour beers.
The taste was earthy, cellar. Probably brett and sacc. No lacto.
Very fruity, estery. Clean sacc only. I used this to ferment a 5l test batch of belgian strong and it came out really well.
In a starter it tasted fruity and spicy. I tried this in a 5l test batch and the result was disgusting, strong bakers yeast smell and taste. Had to throw it all away.
Mort Subite Geuze
There was no growth at all, it is probably pasteurized.
Waldhaus Schwarzwald Weisse
No growth, probably pasteurized
To try next:
Saison du Pont
St. Feuillien de Saison
Duchesse de Bourgogne