Schneider Weisse and Tej yeasts

I have been plating some stuff for practice and fun, trying to work out some of my problems. I think I am leaving the plates out too long at room temperature before streaking them, so they are drying out. You can see the cracks, which are not necessarily where I streaked. I still have a bit of a heavy hand with the needle while streaking so those tend to break the agar in a few days, too. I am usually only making 100ml of media so it’s hard to measure the agar consistently with my regular scale. I need a jeweler’s scale, and perhaps lab grade agar powder instead of the flakes I bought at Whole Foods. This latest batch of media was made with bakers’ type malt extract since I had run out of the brewing stuff. It is very dark and probably not all that great for this. It seems to be giving a hue to the colonies themselves (upper left on the tej plate; is that possible?) in some places. The media is just extract, Wyeast brewing nutrient and agar.

I had a bottle of Schneider Weisse, which is supposed to be bottle conditioned with the fermentation strain.  Some searching showed it’s not the easiest to culture, probably due to age and harsh shipping conditions from Europe. But with some careful sanitation I diluted the dregs in sterile wort and streaked a few days later. I see only yeast on the plate. It was quite slow to grow but it did. I haven’t tried to culture it in liquid.

Tej plate

As mentioned in the Tej post I streaked out the yeast during active fermentation. I saw only yeast at first though after looking at this picture I see what looks to be some type of bacteria colony right in the middle. There is some tang to the tej so I was actually looking for some LAB. I’m still working out how to take close-up shots without too much reflection, so pardon the quality. The cracks in the agar don’t help. There are spots on the outside that kind of look like they’re inside, but they are just hard water stains.


5 thoughts on “Plates

  1. eurekabrewing

    How much agar powder to you mix with your malt extract? I used a malt agar before and added 10 g of dried malt extract and 1.5 – 2.0 g of agar to 100 mL water. And I used baking agar as well. The cracks might originate from a overdose of agar as well.

  2. DC Yeast Lab Post author

    I have been using 3-4 grams per 100mL. I tried once with about 1.5 grams but the plates were almost liquid. It may be a problem using my scale to measure such amounts, and I had to estimate the .5 grams since it only measures in 1g increments. Even with the larger amounts it’s a bit difficult, as it sometimes switches back between 3 and 4 grams. In these small amounts that’s a pretty big difference and could be causing an ‘overdose’ indeed.

    I’m using this instead of powder: since I could get it locally. I wonder if there’s a different moisture content or something to that effect when compared to agar powder.

    I’ll have some time to make new plates this weekend. I will try lowering the amount a bit to see if it helps. I might also make some other type of media, like potato dextrose, since I have not previously used anything other than malt extract or brown rice syrup with added yeast nutrient.

    1. eurekabrewing

      I guess the amount of agar depends on the agar product. I estimated the amount of agar as following: 200 mL water and 20 g of dried malt extract. Then added some agar as it was nearly to a boil. I then took a spoon and dripped some of the starter on the glass surface of my stove and examined the stickiness after it cooled a bit. If the agar was still not firm, I added some further agar. And repeated the dripping process until the agar was firm. I used 4 g of agar in my case. I would suggest to do this process with your agar product as well. I will do this process again next week when I do potato agar. Because I have no idea how much agar I have to add.

      1. bkyeast

        You know guys, the only time I successfully made malt plates without wasting an elephant load of agar on it was from like 3rd running from an all-grain batch (it was VERY dilute, like 1.010 at most), diluted about 2-3 fold and with addition of bromocresol green. No joke. I even made it a “split batch” where I poured half the plated before adding the dye and then added it and poured the rest. Without dye it had the consistency of apple puree, with dye, it was nice and hard enough to streak with a loop. 2g agar per 100mL.
        Weird, I know. I still have a bottle of sterilized runnings to experiment with. I have no idea why malt acts like this, perhaps adding salt would help, but my guess is that THAT’S WAY TOO MUCH MALT FOR AGAR. lol seriously. As far as I know malt plates are 2-4% malt extract. Meaning 2-4g per 100 ml which actually means they’re about 1.002. Try that next time you pour plates and I’ll try diluting my runnings 10X and see.
        You may also want to save a little bit of some yeast cake, add some water, boil it to denature the hell out of everything, cool, add some meat tenderizer (which contains salt and protease), heat denature and use as home-made yeast extract (like a few grams per liter of agar). I haven’t tried doing this because I haven’t had any yeast cakes around, but as I’ll be kegging and bottling soon there will be plenty of it for me to play with. I imagine using the resulting slurry would not be such a great idea because it’s insoluble, but say topping it off to 1 liter, mixing it in a blender for a while, and then filtering it to end up with a clear solution that you can then aliquot, sterilize, and use at say… 50mL per liter sounds like a decent idea to me for a first try. Or you can just use WYeast nutrient which I imagine is about the same thing as yeast extract+peptone or something similar.
        As for cracks… these pictures look like drying plates to me. In my experience when plates begin to dry out they look exactly like this. They don’t become all uniformly dry, but instead crack just like what you have here and then start drying from the cracks into the rest of the plate. Try keeping them in a ziplock bag and they’ll last weeks at room temperature no problem.
        Anyway, good posts, keep ranching!

  3. DC Yeast Lab Post author

    Cool, thanks for all the suggestions. I had assumed the media needed to be fairly rich because I’ve seen 1.020 wort recommended for the first few stages when growing from a colony. It also made sense because I was making the liquid media at the same time as the plates so I had just been taking 100 mL and adding agar.

    I will try making more dilute malt agar (with some Wyeast nutrient as I’ve been doing) as well as potato dextrose this weekend. Would potato dextrose broth be useful for growing a liquid culture, or should I stick to wort for that?


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