Every day millions and millions of loaves of various types of bread are made and eaten around the world, and historical evidence suggests its consumption in the neolithic age (10,000 BC). Many types of bread, especially those consumed in the west, are leavened using a type of fungus called Saccharomyces cerevisiae (also called Baker’s Yeast). For leavening,  the yeast is mixed with a sugar solution to produce carbon dioxide and mixed with the dough to  make the bread lighter and chewable. I have never succeeded in making a satisfactory leaved bread in spite of several attempts, as a result I have several unopened yeast packets.

For this experiment, I dissolved a spoon of jaggery in a cup of warm water (100 F) and dumped some yeast granules and mixed it well. Soon enough the liquid started making copious amounts of carbon dioxide and the liquid overflowed from my cup causing much consternation. On a slide, I put a drop of water and a drop of this liquid, put a cover slip over it and taped it. Gas bubbles immediately formed in the cover slip and I put it under the 100x foldscope lens. Even a drop was a bit too much I realized. The field was filled with glistening yeast cells. In some fields, one could see a developing gas bubble pushing the yeast cells to the liquid phase (Note videos were taken with a Nexus 5 coupled to the foldscope)

Soon the slide was filled with islands of yeast cells in bubbles of carbon dioxide forming interesting patterns. Unlike the cheek cells, at maximum digital zoom, the yeast cells are tiny.

Finally, most of the slide was filled with gas and the yeasts clumped into spherical balls of liquid.

After seeing this, I have an idea for a future experiment, Bromthymol blue is supposed to turn yellow when CO2 dissolves in water. So, I wonder what will happen if I just added a dilute drop of this indicator in the slide. Would I see a gradation of color at the interface of the bubble?

On a sad note, I tried using the highpower lens, but my lens holder seems defective and wouldnt fit through the stage. In vain, I tried making a snout of it to fit into the stage but alas! it tore  🙁  Perhaps I should just tape it directly under the stage to revive it. Manu any ideas how to fix this problem?

Finally a thought. Each 5 g packet of yeast cells has over 90 billion cells. Considering the amount of bread, beer and other liquor that is made, we perhaps use several human population’s worth of yeast every day. We farm yeast to increase our population, while they make CO2 and alcohol for us to increase theirs… which leaves me wondering …Are we are controlling the yeasts or are they are controlling us?