Why would God create bacteria?

Have you ever wondered what purpose bacteria serve? I understand that worms and ants are extremely important for the soil. Algae are extremely important as one of the main converters of carbon dioxide into oxygen. But, one might wonder: Why would God make bacteria? Don't bacteria only serve to make more complex organisms sick? Perhaps God does have a purpose for bacteria that is not generally understood. Although many Christians will deny so called "macro evolution" many will acknowledge that evolution takes place at the "micro" level of bacteria. The evolution of bacteria (and virus) is particularly noticeable in the field of health care. Antibiotics that used to work, don't work anymore because the bacteria have evolved. This is hard to deny. So, to return to my question: What purpose do bacteria serve, besides making us sick? With this question in the back of my mind, I read "Acquiring Genomes" by Lynn Margulis and Dorion Sagan. Here I discovered that bacteria function as the "test labs" (my word, not theirs) of evolution. Every little thing that more complex organisms can do (metabolism, light sensitivity, conversion of sunlight into chemical energy, etc.), was first done (and still is done) by a bacteria. Upon recognizing that bacteria are breaking evolutionary ground, I came to see that they have an important role. More complex organisms don't have to "stumble upon" a new genetic code by random mutation in order to acquire a new trait or start a new species. All an organism has to do is acquire and incorporate into its genetic code a genome that was tested out in the fast paced evolutionary test labs of bacteria. In cases where such an acquisition doesn't make the organism sick, it may serve to provide a benefit. Bacteria provide the "intelligent design" that drives evolution. Beneficial changes remain due to natural selection. It was eye opening to discover that bacteria play an important role: they drive evolution. So, if the question is: Where do new genetic codes come from? The answer is from the trial and error and quick reproductive cycles of evolving bacteria. Micro-evolution enables macro-evolution.