
First, a confession - I have become slightly obsessed with a single cell organism.
I have posted my experience with Brett Drie (WLP644 - Brett B Trois) (Avery 15 Brett) in a couple different online sources so I thought I would compile some of the information.
WLP644 -Brett B Trois - Homebrewtalk Thread
WLP644 - Babblebelt Thread

I have been brewing with this strain for about a year and a half. The back story is that one of my homebrew friends cultured this from a bottle of Avery 15. The yeast is referred to as the Brett Drie strain. If you have read through Chad Y's paper and website he discovered that there are actually 2 strains present (Chad still uses these strains at Crooked Stave in addition to others he has isolated). They were each used in his thesis experiment and the fermentation is well documented.
My friend, Adrian, gave me a vial and Neva at White Labs one too. It took White Lab's quite a while to come out with this yeast and not sure how well it relates to what I have been using. Did they isolated one strain or do any manipulation?)
I do know that I get the flavors and attenuation that others have reported from using WLP644. After my first time using this Brett I was hooked. The tropical fruit notes were great, they literally filled the room when I was bottling.
Best Bitter with Brett Drie -
1.048 - 1.010 - 79% Apparent Attenuation - Mashed 154 - 8% crystal malts - 30 IBUs -no aeration - big tropical fruit - nice w/ Goldings
I have tried it in several different styles of wort since that first test batch (link above) and consider it my house Brett strain. I mostly use it in Primary as in the examples below. (I have also used it at bottling in some Saisons and was not all that impressed with the results - mostly some light traditional Brett funk flavors.)
Old Ale wort -
1.079 - 1.014 - 82% Apparent Attenuation - Mashed 154 - 7.5% Crystal Malts, 8% Turbinado sugar 40 IBUS - 8.6% - aerated - sour and decently complex in 3 months - one of my favorite beers I've ever made or tasted.
Hoppy Bitter (Extra Special Brett-er) - 1.049 - 1.006 - 20 IBUs - Dry-hopped w Nelson - testing it with a Hoppy wort - no aeration - fermentation fruit notes played really well with tropical fruit notes of the Nelson hops - my best hop forward beer I've made.
Table Saison with Rolled Oats - F.G. (.999) - 103% Apparent Attenuation. Mashed at 147 with 80% Pils, 15% Rolled Oats, 2.5% Acid Malt, 2.5% Piloncillo sugar - very clean on first taste, going to dry-hop half with HBC 342 hops (aroma and taste was weak) and now added 1 oz of Calypso hops
Aeration:
The Brett will produce some acid (acetic) if you aerate it well, the acidity is just enough in my opinion to give people the idea that it is a wild beer, but no where near a sharp bite. If you do not aerate, then the yeast will still produce the fruit flavors, but with little to no acidity and a very "clean" taste.
Fermentation:
I get a very quick fermentation from this yeast, but I'm making large starters. I usually start with some saved yeast in a White Labs vial that is 1/8 full of yeast. I do a 4 oz 1.020 starter , then a 32 oz 1.040 starter, then 64 oz 1.040 with a week between each. According to my estimates (very rough) and this calculator (
http://yeastcalc.com/ - based on Sacc), I had some where around 220 billion cells. The majority of the activity seems to be done in a few days and then I get some residual for another couple weeks.

As for temperature, my first batches were all fermented in the 68 - 72 range. Well, for this most recent batch of Spelt Saison I wanted to test this temperature dependence. I split the main batch wort into 2 - 1 gal batches. One batch was fermented with a normal Saison temperature profile (start in the low 70s and free rise into the 80s and held for a week). The other batch was temperature controlled in the fermentation cabinet at 63-65 for 2 weeks and then brought up to mid 70s. The fermentation looked complete after 2 weeks.
Results:
Saison Profile - 1.000 - nice spicy notes, Belgian phenols and light fruit notes
Low Ale Temps - 1.000 - nice spicy notes, Belgian phenols and light fruit notes
I was surprised by the results, both were 100% Apparent Attenuation and 7.9% ABV. These both were allowed to ferment out for a total of 3 weeks before bottling. I'll do an official taste test in the following weeks.
Flavor Progression:
The beer starts very clean (no noticeable acidity if you don't intentionally aerate) with huge tropical fruit flavors. I refer to the flavor as POG (Passion Orange Guava). After a month or so that flavor starts going toward over ripe fruit with a bit of funk. And long term the beer has gotten progressively more sour (I may not have a pure culture), but not more than a mild tartness. And the tropical fruit flavors remain and are mixed with more traditional Brett funk notes.
Bottling/Packaging:
Nothing to worry about if you are kegging, but for bottling I have been waiting about 3 -4 weeks. And the stability in the bottle is great. You can use standard priming sugar amounts. This Brett strain and most of them have very low flocculation. You may need to assist the yeast to floc out with a cold crash and a bit of pressure. Also gelatin and racking will greatly help.
Notes:
One thing I have just noticed in my latest Table Saison with 100% Brett is how clean the fermentation profile turned out. The beer was mashed at 148 with 20% rolled oats. This beer fermented from 1.044 down to 1.000 in about a week. I am thinking that without very many complex sugars (from a higher mash temp or crystal malts) that the Brett does not produce the same esters. Also it did not have a lot of hop compounds to play off either.
Please feel free to ask questions and suggest ideas for future experiments. (I am interested in seeing the fermentation limits of this yeast - 20% Brett Beer anyone?)