Now, it might not be all that shocking to you that your shower is a haven for microbial life. You have probably periodically noticed mold in the folds of the shower curtain and other places. This isn't news to you. But the shower provides a great example to illustrate how the microbes grow. If you have seen pictures of bacteria and fungi before, they are often portrayed as a loose collection of individual cells, typically floating around in a liquid environment. BUT...research is proving that microbial life in nature is not that simple. In the case of your shower, a research group led by Norman Pace (who is famous for other, non-shower-related discoveries) recently published two papers showing that an incredible diversity of microbes are growing in household showers in something called a biofilm.
As it turns out, this isn't unique to your shower. Microbes in nature frequently grow in biofilms. A biofilm is basically just like it sounds...it is a film or mat of microbial cells held together by substances that the cells themselves secrete. Although some biofilms are made up of only one species of microbe, many biofilms include multiple different species. This is really fascinating, because it suggests a level of multi-cellular organization across microbial species. Here are a couple of great micrographs of biofilms...
