Harvesting keg dregs, any advice?

I’m looking for some guidance regarding collecting and reusing yeast dregs. My situation is a little different than most who are trying to culture the dregs from a bottle… I have a 5 gallon corny keg of Saison Athene from Saint Somewhere brewing that I received as payment for volunteering during one of their bottling days. If you’re not familiar with Saint Somewhere, it’s a tiny brewery outside of Tampa that specializes in Belgian farmhouse ales. They open ferment and naturally carbonate everything, so I’m thinking there should be a fair amount of wild yeast in my keg when I finish (which may still be a long while from now). They no longer have to add Brett to their beers because the entire brewery is infected with it, so I would love to reuse the dregs from this keg for some future wild ales that I have planned. I have never collected yeast like this to reuse, so I’m not sure the best way to go about it… Also, this beer was kegged in November and I’ve barely put a dent into the keg, so it will likely be later this year before I finish it and am able to harvest the dregs. Will these yeasties still be viable after sitting dormant that long? I’ll probably throw the dregs into a 3L starter on a stir plate to make sure they’re still viable. If anyone has any feedback, suggestions, etc. I’d love to hear from you!

I think your plan sounds about right. There should still be plenty of viable yeast/bacteria in there once you're done with it so long as it isn't too high an alcohol, is wasn't filtered, or been treated poorly, which sounds like it hasn't. I've not tried anything this intense yet, but check out the Mad Fermentationist's blog. He's got a bunch of info on growing up and storing dregs.

Take a look at what you've got once the keg is done. If there's quite a bit of dregs in there, you could even pitch them into a small size batch (1-2 gal?) and ferment it out to see how it tastes, while growing up more in the process!

It's harvesting yeast from a big bottle. Should work especially since the keg has been sitting undisturbed for a long time. 3L seems big though, unless there's a ton of sediment I would go smaller.

Thanks for the input guys... It will probably be some time from now but I'll post back here with my findings after giving this a go... If I am able to get a good culture going from the dregs I'll probably end up freezing some down to save for future use as well.