Category Archives: Microorganisms

Preliminary Results of YPD deterioration

Absorbance of DI YPD (pink), D2O YPD (green), and blank (red)
Absorbance of DI YPD (pink), D2O YPD (green), and blank (red)

These are the results of the experiment I stated a couple weeks ago. I have been tracking the deterioration (previously called aggregation, but I’m not entirely sure aggregation is the correct terminology) of YPD in both solvents. Today they looked pretty well degraded so I thought I’d share the results. Between the two, the DI YPD is more absorbent than the D2O YPD at nearly every wavelength measure (major uncertainty below 350nm).
I’m associating degradation with absorbance since the blank (which is also DI YPD) has an absorbance of zero at all the same frequencies.

D2O YPD also records 0 for absorbance at 600nm, which is the wavelength used for cell count studies, so there would be no interference from the solution. Whether or not the media is still usable by cells is undetermined.

I’m beginning a second experiment that would track the absorbance every few days via the same mechanism. If you recall, I began this experiment taking pictures and eventually moved toward using the nanodrop. This probe seems to do a good job so its continued use is reasonable.

Man I’ve been writing my dissertation for too long…

D2O Adapted E. coli Experimental Replication

Yesterday while writing I realized that the images of the D2O adapted E. coli that I’ve taken were grown on D2O YPD. In an effort to figure out if the morphologies are due to the YPD or the D2O, I’ve decided to redo the experiments on LB agar.

Today I made some D2O and DI LB broth:

  • 1.84g LB in 92ml of D2O
  • 1g LB in 50ml of DI water
  • Filtered broth for sterilization

Then from there I made some LB agar

  • 40ml of liquid D2O LB with 0.8g of agar (2% agar)

I already have solid LB plates with normal water (commercial).

I then incubated E. coli at 37C in liquid media so that I can streak the plates and analyze them. I used 2 different E. coli:

  1. Normal competent cells
  2. Cells from Day 33.
  3. I also had made a separate culture from an unlabeled glycerol stock that I’m pretty sure I made when I finished the experiment. I’ll check it out tomorrow after the sample has developed.

Yeast morphology in 80% D2O

Yeast Colonies in 60% D2O YPD

So I suck at my own microscopy technique of taking pictures and combining them. In each case I left out a pretty sizable portion of the colony. :( Oh well. I’m going to do these experiments again (cause I made 2 sets of each type of solid media, 0%-100% D2O) and will be taking new images then. Can’t wait!!