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Metabolic Wizardry – Introduction to Microbiology

by Vincent Racaniello, PhD
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    00:00 ways that we take advantage of the extremophiles out there in the microworld. Microbes are also metabolic wizards, they invented photosynthesis. This is the process by which sunlight is converted into energy, and microbes were the first on earth to do that. Many microbes get energy from the chemical bonds in inorganic compounds, such as hydrogen, reduced iron and sulfides, way more than any other lifeform on earth does, and these are reactions in which no light is needed, so the bacteria can grow in dark places, in caves or even within rocks, using inorganic compounds to get energy. You may be aware at the bottom of the ocean, there are communities called vents, deep-sea vents. And these are areas where hot water is shooting out from the center of the earth. And around these events, is an incredible array of life of different sorts, but also there are bacteria and they are able to make organic compounds down there in the dark that all of these other animals can use. Microbes have shaped our earth in many different ways; half of the oxygen that you are breathing today is produced by bacteria. Plants decay because of the microbes that are present in soil, if it weren't for the microbes, the plants would never decay and that carbon would never be recycled.

    01:25 Microbes are the only significant source of nitrogen on the earth; this is essential for plants to grow and microbes take the nitrogen gas from the atmosphere and convert it to chemicals that plants can use. Humans know how to do this, we make fertilizer for example, but microbes are essential for plants to grow. If microbial activities on the planet were stopped, the plants would run out of nitrogen in a week, and we wouldn't be able to make enough fertilizer to make up the difference.

    01:58 You may be aware of a scientific experiment done a number of years ago called BioLab 2.

    02:04 This was a lab built in the desert of Arizona, a few humans were put into this, plants were put into this and the idea was that the humans would be self-sufficient; they would grow all of the food that they would need and dispose of it as well. Well this experiment failed because we didn't put the right bacteria in the soil to generate the compounds that the humans needed to survive. So given water, microbes can break down anything and we use this for remediation. So for example, if there is an oil spill in the ocean due to a tanker breaking or a broken pipeline, we can add bacteria which will then degrade the oil.

    02:46 Microbes also shape the physical earth that we live on, the caves that you are familiar with, with open caverns and the stalactites and stalagmites growing from the walls, these are produced by microbial activity. Microbes actually produce sulfuric acid which plays a role in eroding away the stone. The limestone that makes up so many caves is actually a microbial product. A microbe called a coccolithophore makes about one and a half million tons of calcite each year and that goes towards building these caves. If you look up into the sky and happen to see a cloud today, that cloud is a product of microbial activity. Marine algae, together with bacteria, produce a compound called dimethyl sulfide. They make about 50 million tons of this a year. This goes up into the atmosphere where it turns into sulfate, and that in turn attracts water, and that forms clouds. I'll bet you didn't know that.


    About the Lecture

    The lecture Metabolic Wizardry – Introduction to Microbiology by Vincent Racaniello, PhD is from the course Microbiology: Introduction.


    Included Quiz Questions

    1. Many bacteria can derive energy from inorganic material
    2. Bacteria have developed light-independent photosynthesis
    3. Most bacteria can form spores that grow in times of harsh environmental factors
    4. Many bacteria can convert heat to energy
    5. Bacteria can use decayed organic material for energy instead of photosynthesis
    1. Sulfuric acid
    2. Carbon dioxide
    3. Inorganic material
    4. Sodium Chloride
    5. Oxygen

    Author of lecture Metabolic Wizardry – Introduction to Microbiology

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD


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