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Microbiology Concept Inventory
Please note, you must be an educator in higher ed or maybe high school to qualify to recieve the MCI
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Microorganisms exist in almost every environment on earth and maybe beyond this planet. They were most likely the first forms of life and will probably be the last. It is not too bold a statement to say that if water is in the liquid state and a source of carbon and energy is present, microorganisms can exist. Microbes can grow at temperatures from < 0°C (the snow alga, Chlamydomas nivalis) to 113°C (Pyrolobus fumarii). Think about that, a microbe that can grow in water over 100°C. Water boils at 100°C, how is that possible? The answer is that P. fumarii grows under the sea at hydrothermal vents where the water pressure is very high. Figure 1-1 shows a picture of a hydrothermal vent. Water therefore does not boil above 100°C. P. fumarii has very special proteins and membranes that help it deal with the intense heat and scientists are just beginning to understand the adaptations this microbe must make. While microbes that live at the extreme of temperatures are fascinating, most of the organisms we will examine will grow at 20-50°C. Microbes are also present in saturated salt lakes, in acid mine drainage that is below pH 1, in environments devoid of oxygen, in soil, and on you!
Figure 1.1. A hydrothermal vent. This particlular vent is located in the . Note the large amount of material being precipitated out of the super-heated water (about 300C) as it comes in contact with ocean water at the sea floor (4C).
Whether you measure them by population or total biomass, microbes are the most common forms of life present in almost any environment. You contain more microbes in your digestive track (about 100 trillion) than you have cells in your body (about 10 trillion). The soil is also teeming with microbes. There is a rich nutrient source in the form of leaf litter, dead animals and plants, and organic waste.
Microbes have a large impact on the environments where they grow. In the most general terms, this impact is in the form of their metabolism where they consume available nutrients, use them to create energy and cell material, and then discard waste products. They use this bounty to grow to large numbers.
In nature, bacteria do not exist in isolation. Their biosphere is crowded with many different types of microorganisms competing for food and space.