Info on media for culturing samples

Dave - Sorry it took me so long....I've been slacking. For some reason, I can't respond to your last posting; it might have something to do with the fact that my interface crashed as I was trying to post a response...

Here's the info on growth media. We'll need two different types of media. The first is a generic growth media for grape must - this'll highlight the good and bad yeast, as well as the other bacteria growing in the fermenter. The second will be a Brettanomyces-specific media that will not grow Saccharomyces (the good yeast) but will allow the Brett to grow.

An ideal sampling protocol would be as follows:
- One day after destemming into the fermenter, we'll pull a sample to see what survived the initial dose of SO2. This'll let me know if I'm taking any risk letting the native population of yeast take off or if I should innoculate with a cultured strain.
- As we drain off to barrel, we'll pull another sample to check for Brett on the way to barrel. This'll let me know the risk level and management I need to do in barrel.
- About 3-4 weeks after the wine's in barrel, we'll pull a sample from each lot (not each barrel) to check for any Brett growth. Again, this'll help determine if we need to pull any special tricks to control contamination.

One question for you - Do you have a filter housing that we can use to filter a large (300 ml) sample of juice through a .45 um filter? It's pretty easy to get quick growth from smears made from the concentrate on the filter surface. If you don't have one, how about BC funding some capital equipment for your lab? Think about it, and let me know.

Here are the media recipes:
(Everything below is from "Wine Production and Analysis" by Bruce Zoecklein; in the BC library)

General grape juice growth media:
- Mix 20 g of agar (YM) in approx. 800 ml of grape juice diluted 1+3.
- Fully dissolve agar by holding in a boiling water bath and bring to 1L volume with reserve juice.
- Sterilize by autoclaving

Brett selective media:
- In approx 600 ml of deionized water, add the following:
2.4 ml Bactoglycerol (or equiv)
48.3 g agar (wort or YM)
50.0 mg actidione (cycloheximide)

Actidione is what kills off the Saccharomyces while leaving the Brett happy to grow. It may be incorporated directly into the water used in making he agar.

Let me know if any of the ingredients are expensive, as you now have the open BC expense account for lab supplies. Keep in mind that I can by pre-prepared culture plates (either standard or Brett-selective) for ~ $1/plate from Vinquiry or Millipore...We can always go that option, too.