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?

in our hemos, you divide what you count in 16 of the smallest squares by 4E-6 to get cells/ml.

I used the method from white labs.

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

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.

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

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.

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.

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: https://www.homebrewtalk.com/f163/pics-yeast-under-my-new-scope-273342/#post3371099

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.

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.

wegz15 said:

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.

Click to expand...

I have a spreadsheet that lays it out pretty plain. PM me your email if you want it.

The one I use at work you just divide by 20 (counting 5 of the 25 squares). To give million cells per ml

Did a 600ml starter for some out of date wlp540 on the stir plate and got 68 billion cells.

I figured it out. I used the white labs calculation.

Cell count from 5 squares x 5 (to get the total 1mm area) x 10 (dilution rate) x 10^4 (10,000)(They say its the volume of the counting chamber) =cells/ml

204 x 5 x 10 x 10^4 = 102,000,000 cells/ml

10.2x10^6 x 1000 ml = 102,000,000,000 cells/L

Thanks for all the help guys.

Nice, that's what I calculated too. The really easy way is to just count (square 5 on the whitelabs page you linked, made up of 25 small squares), divide by 4 X 10^-6, and multiply by your dilution factor to get cells/ml. If you are worried about being more precise, count a few of the grids that look like number 5, and take the average.

wegz15 said:

I figured it out. I used the white labs calculation.

Cell count from 5 squares x 5 (to get the total 1mm area) x 10 (dilution rate) x 10^4 (10,000)(They say its the volume of the counting chamber) =cells/ml

204 x 5 x 10 x 10^4 = 102,000,000 cells/ml

10.2x10^6 x 1000 ml = 102,000,000,000 cells/L

Thanks for all the help guys.

Click to expand...

That's the long way round of what we do when we divide by 20

You count 204 cells, divide by 20 (then multiply by the dilution if you do).

(204 / 20) x 10 = 102 (million/ml or 10^6)