Download Lecture outline Microbial ecology and communities

Lecture outline
Microbial ecology and communities
Intro to microbial ecology:
Microbial ecology is the ecology of microorganisms: their relationship with one another and with
their environment. Microorganisms are very small, ranging from about 0.1 um to 100 um (Fig. 1).
Microbes are unique in their large surface area to volume ratio. Microbes are also very diverse,
contained in all three major domains of life—Eukaryota, Archaea, and Bacteria—and also include
viruses. Microbes are also ubiquitous and impact the entire biosphere, including some of the most
extreme, from frozen environments and acidic lakes, to hydrothermal vents at the bottom of the
deepest oceans, and some of the most familiar, such as the human small intestine. They play
primary roles in regulating biogeochemical systems in virtually all of our planet's environments,
for example carbon fixation, nitrogen fixation, methane metabolism, and sulfur metabolism. The
vastness of microbes’ production is such that, even in the total absence of eukaryotic life, these
processes would likely continue unchanged.
Key Concepts for the Lecture:
1. The Marine Environment
● Marine vs terrestrial
● Light availability
● Buoyancy
● Oxygen availability
● Specific heat
2. What microbes are present in the ocean?
● Bacteria
o Cyanobacteria
● Fungi
● Diatoms
● Dinoflagellates
● Viruses
3. What is the role of microbes in the ocean?
● Primary production
● Biogeochemical processes (nutrient cycling)
● Ecosystem health and diseases
● Potential benefits from marine microbial research
4. Why should we care about microbes?
● Study how emerging diseases are responding to climate change, acidification, coastal
urbanization, pollution
● Potential of integrating microbes into our biogeochemical and ecosystem health
forecasts
5. Effects of environmental factors on microbes
● Nutrient
●
●
●
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Temperature
Pressure
Salinity
Ion concentration
6. How do microbial ecologists assess microbial communities?
● Culturing techniques
● High-powered microscopes
● Molecular methods
● Species richness
● Species evenness
● Species diversity
● Community similarity
Figure 1. Relative sizes and detectability of organisms. Key point is that bacteria are about the size
of mitochondria, an important organelle in animal and plant cells (Mahr,
http://cnx.org/content/m47858/latest/)
Another resource for demonstrating scale: Website showing the scale of the universe:
http://htwins.net/scale2/
Figure 2. Global ocean and terrestrial photoautotroph abundance (1997-2000) estimated by
chlorophyll a concentrations (mg/m3) (http://en.wikipedia.org/wiki/Primary_production).
Figure 3. This diagram offers a basic illustration of the depth at which different colors of light
penetrate ocean waters. Water absorbs warm colors like reds and oranges (known as long
wavelength light) and scatters the cooler colors (known as short wavelength light). Image courtesy
of Kyle Carothers, NOAA-OE http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/deeplight.html