I setup new cultures for 99% D2O and 50% D2O making this the 4th generation of yeast in D2O. Yesterday I ran out of D2O YPD and had to deal with a smaller batch for the 50% D2O yeast. Today I made some new 99% D2O YPD and inoculated 1ml of each yeast-water type in 9ml of each YPD type. Then I took some measurements.

Today’s Absorption measurements are:

• D2O (Generation 3) – 2.351 at 24h
• 50% D2O (gen 3) – 2.65 at 24 h
• D2O (gen 4) – 0.041 at 0h
• 50% D2O (gen 4) – 0.419 at 0h

It was interesting to find that the 24h batch of 99% D2O yeast had an absorbance of 2.351 for 2 reasons; 1) that’s a good amount for 24h from what I’ve been observing and 2) because my 1:10 dilution resulted in a much different absorption than 50% D2O yeast (note that they started at a similar value).

When I tried to analyze by eye it was apparent there was a difference in absorbance but it definitely didn’t look 10x less clear. But I did notice that the cells in 50% D2O seemed to be pretty uniformly “dissolved” (I don’t really know what to call that). Meanwhile, the cells in 99% D2O seemed to form larger clumps and the average “particle” size (I’m guessing they are colony clumps) was larger than the clumps in 50% D2O.

I’ll have to analyze this under a microscope and report observations, something that will have to wait until tomorrow or next week.