Yeast Maintenance

[WBC]

This is an excellent read for those of you who want to re-use liquid yeast over and over. I recently bought a microscope and really like the way it teaches me what I can and can not do when pitching yeast and maintaining a good supply of my favorite strains. Over all you may save money over time but the biggest point is I now know I will not have any problems when I pitch my yeast as I know what is in it and how viable it is (how many viable cells I have/per volume of yeast) before I brew.

 

[Piotr]

That microscope thing is tempting me for some time...
Tell me, how expensive is a microscope adequate for homebrewing puproposes, and is it easy to estimate that cell count and viability?

 

[WBC]

That microscope thing is tempting me for some time...
Tell me, how expensive is a microscope adequate for homebrewing puproposes, and is it easy to estimate that cell count and viability?

You need a microscope with a resolution of 400 X to look at yeast and bacteria.
I would choose one that is not a toy but with quality optics. I bought mine on ebay and it will magnify up to 1000 X and has a mechanical stage with micrometer xy adjustments so you can accurately move around instead of moving a slide by hand. It also has a light intensity adjustment and most other features on a biological microscope. I will list some reference links at the end of this message. You do not have to spend $200.00 on a microscope but remember "you get what you pay for".

You need a dye marker fluid to mark dead or dying cells so you will not count them in a special slide called a hemacytometer which is etched with a grid so you can count accurately. The slurry sample is diluted in sterile water 10 or 100 to 1 for the counting. Instructions come with the hemacytometer.

You can read about using all this stuff on the internet. They talk about human cells but yeast are counted the same way. Watch the video a couple of times as it shows what cells look like while counting and the use of a marker dye to stain dead cells.

Counting cells: http://humgen.wustl.edu/hdk_lab_manual/hcc/hcc7.html

Video of counting cells: JoVE: Counting Human Neural Stem Cells (Video Protocol)

Microscope: Look at this Microscope as this is what I bought and it was suggested by a microbiologist as a good one for the price. Having used it I can agree. You can also pay $50.00 more and get the trinocular model which accepts SLR cameras so you can share your pictures with anyone. The camera can be a digital or film type.

Hemacytometer: http://store.changbioscience.com/qj1102.html
also available on www.EBAY.COM

How to culture yeast: http://www.ableweb.org/volumes/vol-15/15-dennison.pdf

Maltose falcons, culturing yeast: MB Raines, Ph.D. - Guide to Yeast Culturing for Homebrewers - Maltose Falcons Home Brewing Society (Los Angeles Homebrewing)