Welcome to BIO121/ESS120: Introduction to Environmental and Ecological Microbiology at UC Merced! This page provides additional online content associated with the course, including short video lectures by Professor Beman, additional videos and interactives, and additional reading materials.
Terrestrial Microbiology – Part 1
As we learned, there are a billion microbes in a gram of soil. There is a huge diversity within this billion—from pathogens like tetanus bacteria, to ‘helpers’ like nitrogen fixers. Some microbes live on or in plants themselves, but these are symbionts that we will discuss later. The vast majority of terrestrial microbiology is therefore soil microbiology.
Soil isn’t dirt, but it did make your lunch. On land, pretty much everything that ate something (that ate something…) ate a plant. This is the food chain/web that you’ve learned about for a long time: wolves eat elk, the elk eat plants. But we should also recognize that all of those plants—from the crops we deliberately cultivate, to the plants that fuel entire ecosystems—grow in soil. They draw water and nutrients from soil, and can’t survive without it. It turns out that microbes are an important component of this.
4.1 Intro to Microbial Life in Soils. This video lecture provides a quick intro to soils and microbial life within them. If you have taken soil science, some of this may be a review, but please watch it. As always, pause, stop, rewind, and take notes as needed!
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4.2 Life in Soils. This video from the California Academy of Sciences provides a brief intro into life in soil, including microbes. The Cal Academy has a very cool building and exhibits located in SF (they actually have an indoor rainforest and coral reef!). They also employ many scientists doing top-notch research. I like this video because it provides a good quick animation of life in soil. We will discuss many of the microbe things mentioned here.
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4.3 More Soil! As you probably know, soil is full of all kinds of creepies and crawlies that you may have played with as a kid. There are also lots of microbes, which is why you always want to wash out a dirty cut so it doesn’t get infected.
These pages from UC Davis provide a great overview of soil and life within it. There are many different interactive diagrams and fun pieces of information. Please read through all the pages below, and be sure to click on all the interactive parts of the diagrams. Links are available below and also in the top menu bar of all the pages.
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4.4 Water in Soil and Methane. This video lecture discusses the importance of water in affecting microbial activity in soil. We already learned about the overall structure of soil, and where microbes live within the soil matrix. Water turns out to have a strong effect on them. I’ll summarize three main points, going through the second point in detail, as it connects to redox chemistry and ultimately to methane production.
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4.5 Drivers of Earth’s Climate (and ecosystems and soils…). Finally, we just learned about how water affects microbial activity in soils, and next week we will examine differences across soils. Both are strongly influenced by the availability of water—through precipitation or irrigation—and also temperature. These are obviously major properties of Earth’s climate, from the warm humid tropics, to the cold and dry poles. This article described the major drivers of Earth’s climate, which helps place this week and next week into context. Please read it fully!
Beman Lab, University of California, Merced 