Yeast Identification

[tCan]

I have the ability to capture, culture, smear and select yeast during my bio lab in university. How does one select suitable colonies for culture? I have at my disposal some simple supplies such as hemocytometers, a few dies(such as would be used for staining nuclei, cell membranes, etc.) And respectable enough microscopes for the task. Some other supplies may be available.

Any suggestions?

 

[smokinghole]

Culturing, streaking and isolating are just basic lab skills you'll pick up at school if you haven't already. So what you have to do is capture whatever you can capture and then streak it out on a plate. If you're using a medium that doesn't differentiate through chemical or antibiotic use then you'll have to look at each colony separately. If you can grow anaerobically/aerobically as a method of selection that would be a help. At least you could rule out the aerobic bacteria that you'd have in the culture mix. Then you would have to do a colony by colony selection looking at each one on the scope. It'll be easy to tell the difference between yeast, bacteria, and molds. If you find what looks like yeast then you streak that onto another plate and check the colonies again. You may have had a mixed colony on the first plate and this will help clean it up if you want a pure culture. Then you just keep working with it until you are confident you have a nice pure culture and all the colonies look and grow the same.

There are other mediums you can use that will kill off all the bacteria and leave the yeast. I don't have the recipe for it but I'm sure I could find one, you could also ask your professor.

 

[tCan]

Maybe I should start with yeast on grapes.... (I'm after wine yeast) My real problem is that I don't have a good means of storing yeast. Since yeast mutates so readily, I'm not sure if the effort is worth it....

The best I would be able to do is keep them in a jar. Pour out half the sample, add water and a tablespoon of sugar. Repeat weekly. Would that work?

 

[smokinghole]

Will they let you freeze some if they have a -80C freezer? If you can use plates just use a swab or inoculating loop and get the yeast off the grape skin and streak it on a plate.