As I was clearing my medicine cabinet I noticed a poorly used bottle of a probiotic formulation mainly containing the yeast Saccharomyces boulardii and several bacteria found in dairy. I remembered that the tablet’s size was a big deterrent and it occupied my cabinet untouched for many years and so I suspended a few small grains of the lyophilized material. Each tablet almost had one human-population full of colony forming units (cfu) or live organisms.

I thought I would see a mix of bacteria and yeast but I could only see the yeast. At low power I could easily see Brownian motion of the yeast in the video though not as vigorous as the Brownian motion of the fat globules in the milk sample .

There was also a lateral motion and it became more pronounced at high power.

On scanning the slide I realized that the yeast was perhaps making CO2 that was causing them to clump. I suspect the yeast was lyophilized at exponential phase. This is very similar to what I observed with Baker’s yeast , although since there was no sugar in this current medium, the rate of gas formation wasnt as much. Ultimately, they clumped into nice regular circles or arrays.

Was disappointed to not see the bacteria, but was happy to see the high power work. Just another adventure with a powerful paper microscope.