I asked Boulevard if I could get yeast from their bottles. Below is what they told me. Good guys.
I think it's cool that you're starting to collect yeast. I know of a few homebrewers that do this as well. Unfortunately, you won't be able to harvest the strain that we use for primary fermentation from any of our bottles. During our filtration process, we run the beer through a centrifuge which is going to eliminate any yeast that's left over after doing yeast blowouts on the tank. We then dose a completely different strain for bottle conditioning.