What's a good way to sterilize yeast?

[Lyikos]

I have captured a strain of wild yeast by dunking some of my backyard fruit in a solution of sugar and yeast nutrient, and so far it was been fermenting nicely. As expected I also caught a bunch of bacterial infections with it as well.I don't have the resources to properly culture it in petri dishes and collect a yeast only colony on an inoculation loop. I'd like the experiment with a clean strain of the yeast, so I need a way to kill of the bacteria, but not the yeast.

Any ideas of a cheap way of doing that?

 

[carrolte]

you can try a jello gelatin dme starter mix poured onto a plate coveredmin saran wrap. use a paper clip as inoculation loop.

 

[Accidic]

Agar is really laughably cheap. I bought 25g for 87 cents at an asian foods store and I live in virtually podunkville usa. I've read negatives with gelatin ones and def don't use jello. Mason jars, salsa jars, or if you had to the saran wrap method works. Malta can be had at publix or similar for about 1.80/6pack of 7oz bottles. Paper clips or needles work. Personally I use a twist tie with the paper removed made into my loop with a butane lighter to sterilize. Net investment: about 3 bucks. Btw, I did a sterilizer with the microwave (before I had access to a pressure cooker) with np with contamination but make sure you watch it or leave a lot of room as it likes to bubble in the microwave. Some people have also been fine with just boiling.

You can theoretically split to "sterile" but I doubt you can make it more cost effective.

 

[Clementine]

The short answer you can wash it in Chlorine Dioxide

http://www.beer-brewing.com/beer-brewing/brewers_yeast/yeast_washing.htm.

However you may have multiple yeast strains and not just one. Some maybe great brewing yeast other may taste like crap or attenuate too much or not enough. That is why you generally plate out your yeast captures and isolate a single colony so you can assess that one variety.

The only things you need to plate out your culture is a Pressure cooker (poor mans autoclave) A plate they only cost a couple of dollars on ebay and some agar and DME. My pressure cooker was the best thing I bought for playing with yeast. Being able to sterilize not just sanitize stuff makes a big difference. It probably has paid for itself as I save all the wasted wort from brews (dead space in Mash tun and boil kettle) and normally get more than enough wort for my next brews starters that I can (pressure cook).

Also if you planning on growing up your yeast you will want sterile wort to do it with, as you are starting out with such small number of cells you want the wort to be sterile not just sanitized with the boil.

There is a wild yeast forum on this site where they will be able to tell you so much more.


Clem