I think i finally caught some!!

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frod1963

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I put out an Agar plate open on my back deck for about 10 hours one week ago. I then closed it up and let it sit in my kitchen upside down and sealed until last night. I had an interesting mix of what seemed to be two small patches of yeast and various other molds. I re-plated the two colonies to two fresh plates late last night and here Is what one looked like this afternoon about 17 hours after transfer. Plan is to bring them with me to my Micro class next Saturday and check them out and maybe isolate some pure colonies. Then it's into a nice blonde base beer for testing. I'll add some better pictures as this thing comes alive.

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Checked the "yeast" out under a microscope in lab this past Saturday and it looked promising. I was able to see nuclei which means that it's not bacteria. I did a 1L starter around 1.030 and used about 100ml to inoculate from the plate. After 36 hours I added about another 200ml of wort. So far it still smells a little sweet and slightly musty? Maybe I caught some Brett instead?

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The easiest way to tell if you have brett or not is to use a wild yeast differential media like Lins Cupric Sulfate Medium. I don't know of recipes that you can use for differentiation besides just a bottle of LCSM. I will check a folder at school that was left to the lab assistants. Apparently it has a giant packet of media recipes that the previous Micro prof left for us to use. I need to copy it for myself anyway so this will remind me to check.

Another way for you to check is to compare a plated sample of a known Saccharomyces yeast to your captured yeast. Then you can also check a known Brettanomyces and see which one it more closely resembles. The bretts are typically smaller and more oblong than round when fully grown. Another potential way would be to make MYPG plates at about 5 pH and then add a bromocresol green pH indicator if possible. The brett should produce acetic acid in the presence of oxygen which after 4-5 days of growth on the plate should change the color of the plate from blueish to puke green. I haven't used that method myself but I will look into if my school has the pH indicator and give it a shot.
 
Sounds good. I'll have to see if we have any of the LCSM media in the lab.
If you find some, could you post the ingredients? I am trying to find a recipe for LP, LCSM, LMDA and LWYM, but even the Handbook of Microbiological media (more than 7000 recipes and formulations) makes no mention of either one of these.

Jasper
 
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