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Old 03-16-2012, 04:46 PM   #1
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Default yeast slant + hemocytometer

So I started stepping up a yeast slant. I put it in a 50ml starter for 24 hours. I then stepped it up to 1l starter for 48 hours.

I did a hemocytometer count today with a 1:10 dilution. In 5 boxes I counted 204 cells. According to my math this would be roughly 4 billion cells(408x10^4 cells/ml x 950ml=~4b cells) in the 1L starter (~950ml), correct?
My OG is calculated at 1.083. For this I calculated I need roughly 300 billion cells.

I just started stepping up my 1L starter to a 2L starter taking 20ml from the 1L and added it to the 2L. I plan to leave this for about 36 hours and do another cell count.

Am I doing the right math and step?



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Old 03-16-2012, 04:48 PM   #2
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in our hemos, you divide what you count in 16 of the smallest squares by 4E-6 to get cells/ml.



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Old 03-16-2012, 05:04 PM   #3
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I used the method from white labs.

http://www.whitelabs.com/beer/cell_count.html

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Old 03-16-2012, 05:26 PM   #4
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those are gridded differently than the ones in our lab, I'm sure their instructions are right, and your numbers seem to be in the ballpark.

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Old 03-16-2012, 05:44 PM   #5
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Thanks. I just wanted to make sure. First time counting and stepping up a slant.

So in my 1l starter I have about 3 billion total cells. Seems like I will be stepping it up forever to get 300 billion

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Old 03-16-2012, 06:39 PM   #6
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your math is off somewhere. I got 1 x 10^8 cells/ml = 102 billion cells/Liter, which is closer to what I would expect in a 48hour starter. The way they have you count is strange, but I'm sure their instructions are accurate.

204 cells in five squares X 5(factor for whole cell) X 10 (diln factor) X 10^4 (volume correction) = 1.02 X 10^8 cells/ml X 1000 = 1.02 X 10^11, or 102 billion per liter.

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Old 03-16-2012, 06:43 PM   #7
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aha, my lab's method comes out the same, but is a little less accurate for counting. I just count 1 of the larger squares, made up of 25 of the tiny squares (designated by #5 in the diagram you linked to).

Then divide that number by 4 X 10^-6 (corrects for volume in the cell), and multiply by your dilution factor. It gives the same answer if i use 1/5 (you counted 5 of those squares) of your count.

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Old 03-16-2012, 07:01 PM   #8
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I found an Hemocoytometer Counter app for the iPhone that I use sometimes. It does work. It gives me the same numbers that my spreadsheet does, so it works.

I have a pic of it here: http://www.homebrewtalk.com/f163/pics-yeast-under-my-new-scope-273342/#post3371099

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Old 03-16-2012, 07:02 PM   #9
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So I really have 102 billion in the 1L flask? That makes me feel a lot better. Felt like I was wasting time and DME for the starters.

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Old 03-16-2012, 07:06 PM   #10
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I've seen your thread pawn. That's why I got the hemocytometer. I had 2 microscopes from my dad laying around. One only goes to 200x but the better one goes to 1000x.

I have an android and the program I used said my solution had 408x10^4 cells/ml. I then took that and multiplied by my volume of 950 ml to get the 3 billionish cells. I think I may be using it wrong.



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