Bacteria's Role in the World: A Study Guide

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Most of us don’t think about the microscopic creatures that dominate our world, but it can be interesting and exciting to learn about bacteria’s role in the world. Bacteria play an important part in our digestive system, and are our main source of beneficial vitamins and amino acids. Some bacteria also provide nitrogen for plants to help them grow well in soil, or cycle important gasses such as carbon and sulfur. They can be found all over the earth, deep down in the ocean floor and high up on Mount Everest. They are a vital component to our earth and to our lives.

Different Types

Bacteria can be classified in many ways, depending on their preferred environments and what gasses they consume. Here are a few important classes of bacteria to familiarize yourself with.

Shapes: There are three basic shapes bacteria are usually found in. These are coccus (round circles), Bacillus, (rod shaped), and spirillum, (spiral shaped).

Arrangements: They can also be classified by what arrangements they grow in. If they group in twos, they are called diplo, if they grow in clusters like grapes, they are called staphlo, and if they grow in singular lines they are called strepto. These prefixes are put at the beginning of their names such as staphlococcus.

Response to oxygen- Bacteria can be grouped by their different responses to oxygen.

Aerobic Bacteria- These bacteria lives in the presence of oxygen and need it to live and survive.

Anaerobic Bacteria- Conversely, these bacteria cannot tolerate oxygen and die in its presence.

Facultative Anaerobic Bacteria- These Bacteria can live with or without oxygen, but prefer to grow in oxygen, and grow better in its presence.

Bacteria can also be classified by how they obtain their energy. If they fix CO2to make their own food source, they are autotrophs, if they rely on deriving their energy from the environment, they are known as heterotrophs.

Bacterial Contributions

Digestion: Bacteria play a vital role in digestion, for humans and ruminants. In humans, bacteria naturally found in our digestive system is called natural flora. They feed on leftover food in our digestive system and in return produce beneficial chemicals such as vitamin K, biotin, and amino acids. In ruminants they help them digest cud and turn it into useful nutrients for them to absorb.

Ecosystems: Bacteria are also an important component to our ecosystems as some can cycle nitrogen in the soil, which is a vital component for plants. They also cycle other important gasses such as nitrogen and sulfur. Bacteria help decompose organic matter, carbon, oxygen and hydrogen and return them back to the environment.

Protection: We also have natural flora on our bodies that help protect us from harmful bacteria. Our skin is inhabited by protective flora such as Staphylococcus epidermidis and Propionobacterium. Normal flora is also found inside the body the nasal cavity, oral cavity, digestive system and urogenital areas being common. As long as they are kept in check with good hygiene and a healthy diet, these flora are helpful and outcompete harmful bacteria that comes our way.

Keeping Bacteria in Check

Although a major fraction of bacteria is beneficial to ourselves and our environment, some types of bacteria we come in contact with can be harmful. Our natural flora can get out of hand with improper hygiene, or poor diet. For example, not drinking enough water and holding your bladder for extended periods of time can increase the risk for urinary tract infections, as bacteria can travel up the urinary tract causing an infection. We are constantly in contact with harmful bacteria. Most of the time our immune systems can take care of this, but simple precautions such as washing hands, covering our mouths when we cough, and staying away from others when we are sick can help make our lives easier.

Websites For Help

Here are a few kid-friendly websites to help learn about bacteria’s role in the world.

Dr. Douglas Fix, ( This website is about normal flora on our bodies and lets you point to a part on the human body, and it will tell you the normal flora that resides there.

biology4kids, ( This is a great website for younger kids, getting them familiar with the basics of microbiology and bacteria.

MicrobeWorld, ( This is an excellent website that keeps you up to date with the latest discoveries and issues about microbes and bacteria.

Science Kids, ( For those who learn better visually, this website is great, because it offers many video clips about bacteria.


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