First off, we turned in our Products for the pH Engineering project...the final posters, that is. We then moved on to look at some of the solutions that were left out over the weekend. In our pH 4.4 solution, we appeared to have some tiny amount of microorganism growth. There were a few clumps floating in the solution, each of which was made of millions of bacteria, most likely. Our mystery solution ended up having a far thicker sludge of organisms built up in it, which is not surprising given that it had an even higher pH (and thus less bacteria killing acidity) of 5.4. Why so much growth? Well, when we made the anthocyanin, we were basically making a tea or infusion of the organic molecules in the "skin" of the cabbage. These molecules have plenty of energy for microorganisms to use to feed off of and grow and reproduce, which is what they did. In both the mystery solution and the pH 4.4 solution, bacteria, molds and fungi had invaded and were eating the leftovers floating around.
On the other hand, we had the anthocyanin solution I had made Friday. It was still in good shape...why? Because of the isopropanol (rubbing alcohol) I had added to prevent bacterial growth. Ditto for the Vinegar, which has a pH low enough to prevent growth. (This is a different mechanism, by the way. Alcohol has a pH close to that of pure water, so it isn't acidity that prevents microorganisms from growing.) On the other hand, the anthocyanin indicator I had boiled to concentrate had tons of microorganisms in it. Why? When I boiled it, all the alcohol boiled out before the water did...so there was nothing to preserve it. The anthocyanin indicator I had thickened with xanthan gum was also turning back into a liquid because the bacteria were chewing up the molecules that had made it thick and jelly-like.
All this raises a question or two: if microorganisms are so small, how could we see these? The answer is, of course, that we could see them because they were lumped together in large groups called colonies or plaques. How, then, can we examine them individually or in more detail? The solution was today's exercise, which was to get out the microscopes and figure out how to use them properly. We spent some time just investigating the different parts and mechanisms, and then moved on to using the microscope to investigate newspaper under magnification.
In social studies, we started talking about a core cause that would lead to the age of exploration and specifically to some of the first settlers coming to the North American Coast: the effects of Christianity as the dominant religion and cultural factor in Western Europe. We brainstormed some of what we already knew about this ancient and successful religion, and then started working our way through the text "The Foundation of America: Religion." Our goal is to ask questions about the text and then record what we learn as we go. We will likely finish this tomorrow in class. It should be a good discussion, I hope.
No homework today. Ta!