Download Helpful Bacteria

Helpful Bacteria
Jessica Harwood
Douglas Wilkin, Ph.D.
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AUTHORS
Jessica Harwood
Douglas Wilkin, Ph.D.
EDITOR
Douglas Wilkin, Ph.D.
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Printed: February 1, 2015
CONTRIBUTORS
Doris Kraus, Ph.D.
Niamh Gray-Wilson
Jean Brainard, Ph.D.
Sarah Johnson
Jane Willan
Corliss Karasov
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C HAPTER
Chapter 1. Helpful Bacteria
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Helpful Bacteria
• Identify how bacteria are beneficial to humans.
• Explain how bacteria are used in food production and medicine.
• Summarize the role of bacteria in digestion and as decomposers.
Where does cheese come from?
Bacteria are often used to make cheese from milk. But making foods is not the only beneficial role of bacteria. For
example, they also play an essential role in your gut!
Helpful Bacteria
Can we survive without bacteria? Could bacteria survive without us? No and yes. No, we could not survive without
bacteria. And yes, bacteria could survive without us.
Foods
Bacteria can be used to make cheese from milk. The bacteria turn the milk sugars into lactic acid. The acid is what
causes the milk to curdle to form cheese. Bacteria are also involved in producing other foods. Yogurt is made by
using bacteria to ferment milk ( Figure 1.1). Fermenting cabbage with bacteria produces sauerkraut.
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FIGURE 1.1
Yogurt is made from milk fermented with
bacteria. The bacteria ingest natural milk
sugars and release lactic acid as a waste
product, which causes proteins in the milk
to form into a solid mass, which becomes
the yogurt.
Medicines
In the laboratory, bacteria can be changed to provide us with a variety of useful materials. Bacteria can be used as
tiny factories to produce desired chemicals and medicines. For example, insulin, which is necessary to treat people
with diabetes, can be produced using bacteria.
Through the process of transformation, the human gene for insulin is placed into bacteria. The bacteria then use that
gene to make a protein. The protein can be separated from the bacteria and then used to treat patients. The mass
production of insulin by bacteria made this medicine much more affordable.
Digestion
Bacteria also help you digest your food. Several species of bacteria, such as E. coli, are found in your digestive tract.
In fact, in your gut, bacteria cells outnumber your own cells!
Decomposers
Bacteria are important in practically all ecosystems because many bacteria are decomposers. They break down
dead materials and waste products and recycle nutrients back into the environment. This recycling of nutrients, such
as nitrogen, is essential for living organisms. Organisms cannot produce nutrients, so they must come from other
sources.
We get nutrients from the food we eat; plants get them from the soil. How do these nutrients get into the soil? One
way is from the actions of decomposers. Without decomposers, we would eventually run out of the materials we
need to survive. We also depend on bacteria to decompose our wastes in sewage treatment plants.
Summary
• Bacteria can be used to make foods and medicines.
• Bacteria play an important role in animal digestion.
• Bacteria recycle nutrients in the environment.
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Chapter 1. Helpful Bacteria
Explore More
Use the resources below to answer the questions that follow.
Explore More I
• Intestinal Flora: A Virtual Organ at http://www.youtube.com/watch?v=yFwrHoKkZBc (2:15)
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/57425
1. How does the gut bacteria differ between the small intestine and the large intestine?
2. What can happen if something causes a reduction of "good" bacteria in your gut?
3. How do the number of bacterial cells in your intestines compare to the total number of cells in your body?
Explore More II
• Gut Microbes in Early Life Have Effect on Adult Emotions at http://www.youtube.com/watch?v=ADhDC
MBwMFs (1:15)
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/57426
1. What is one of the uses of serotonin in the body?
2. What have scientists discovered about the relationship between gut bacteria and serotonin?
3. What do scientists hope to do with this information?
Explore More III
• Putting Bacteria to Work at http://www.pbs.org/wgbh/nova/tech/putting-bacteria-to-work.html
1.
2.
3.
4.
5.
How are bacteria used in making foods? What food are made with bacteria?
How are bacteria used in oil spills?
How are bacteria being used in nanotechnology?
How are bacteria used to combat insect pests?
How have bacteria been used in medicine?
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Review
1. How are bacteria helpful in ecosystems?
2. How are bacteria beneficial to your health?
3. List two foods produced with the help of bacteria.
References
1. Mom the Barbarian. Yogurt is made from milk fermented with bacteria . CC BY 2.0
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