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Field Studies -types of bacteria found on the body.

Field Studies -types of bacteria found on the body.

Introduction: (Initial Observation)

Bacteria are often known as the causes of human and animal disease. However, not all bacteria are pathogen. For example certain bacteria known as actinomycetes, produce antibiotics such as streptomycin and nocardicin; others live symbiotically in the guts of animals (including humans) or elsewhere in their bodies, or on the roots of certain plants, converting nitrogen into a usable form. Bacteria put the tang in yogurt and the sour in sourdough bread; bacteria help to break down dead organic matter; bacteria make up the base of the food web in many environments.

Bacteria are of such immense importance because of their extreme flexibility, capacity for rapid growth and reproduction, and great age – the oldest fossils known, nearly 3.5 billion years old, are fossils of bacteria-like organisms.

In this project you will study the bacteria found on your body. Your study includes collecting and growing bacteria in order to identify their properties. You will observe the color of bacteria and their colony shape.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.  

Project advisor

Information Gathering:

Find out about bacteria and how they are classified. Read books, magazines or ask professionals who might know in order to learn about the methods that you can use to collect, grow and observe bacteria. Keep track of where you got your information from.

Following are samples of information that you may find.

Bacteria are living things that are neither plants nor animals, but belong to a group all by themselves. They are very small–individually not more than one single cell–however there are normally millions of them together. They can multiply really fast.

Classifying bacteria on the basis of their morphology is extremely difficult; bacteria are generally quite small and have simple shapes, though there are some bacteria, notably the cyanobacteria and actinomycetes, with sufficiently complex morphology to permit classification by shape. In addition to shape, bacteria have traditionally been identified and classified on the basis of their biochemistry and the conditions under which they grow. The advent of molecular biology has made it possible to classify bacteria on the basis of similarities among DNA sequences, and has revolutionized thinking in bacterial systematics. The cladogram above is based on DNA sequences that encode ribosome structure.

 How do they look like?
Bacteria can be commonly found in rodlike, spherical or corkscrew shapes and can be seen as single cells or as pairs, chains or clusters. Bacterial cells are very different from human cells in a couple of ways:

  • The bacterial cells have a wall,
  • The nucleus (the area of the cell where all the genes are stored) of the bacterial cell does not have a special membrane to separate it from the rest of the cell.

All the different types of bacteria have been grouped to make identification easier. These groupings or “Divisions” are then grouped a bit more into “Classes”, which are divided into “Orders”, orders are further grouped into “Families” and families grouped into “Genera” (jen-er-a) and genera into “Species” (spee-sheez). A bacterial species is a group of cells which are very similar to each other.

This system of grouping allows scientists to carefully name any newly found bacterium so that it will not be confused with known bacteria. These names have a first (the genus) and last (species) name just like we do. But they are a bit harder to spell! Because there are two parts to the name, the naming system is called a “Binomial” (bye-no-meal) system.

For example:
Escherichia (esh-er-ishia) coli (col-eye) – see what I mean about spelling?

This is very similar to the grouping system that humans are a part of. For example:
Homo sapien(say-pee-en) – this is the binomial name for humans.

The shapes, groups and cell wall types as well as bacterial size and which food(s) the bacteria use are important to help tell one species of bacterium from another. The science of classifying living things is called “Taxonomy” (tax-onoh-me), from the Greek words taxis=order and nomos=law

Some Dangerous Bacteria

Binomial Name Disease(s) Ian’s Pronunciation
Yersinia pestis Bubonic plague yer-sin-ea pest-iss
Salmonellosis Salmonella species sell-mon-ella
Bacillus anthracis Anthrax baa-sill-us anne-threy-sis
Coxiella burnetii Q Fever cocks-e-ella bur-net-e-eye

Some other places you can find bacteria are:

  • Yogurt
  • Your intestines
  • Animal droppings
  • Dirt

Parents Please Note: The phonetic representations are meant as a guide to pronunciation only. Sound out each group of letters slowly, then faster and faster until they become a word.

(or-ga-nizz-em) Any living thing. A “Microorganism” is a very small (micro-) organism.

 Types of Bacteria: There are many different types of bacteria. Some bacteria are rod-shaped (these are called bacilli), some are round (called cocci, like streptococcus bacteria), and some are spiral-shaped (spirilli) or are incomplete spirals.
Some bacteria need atmospheric oxygen to live (these are called aerobic bacteria), but others do not (these are called anaerobic bacteria; they get their oxygen from other molecular compounds).Another way to classify bacteria is by whether or not the bacteria absorbs a dye called “Gram stain” (a violet dye named for its developer, the bacteriologist Christian Gram). Gram positive and Gram negative bacteria have a different type of cell wall, and therefore, a different reaction to the dye and to some other chemicals, including antibiotics (chemicals that can sometimes kill bacteria).

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is to find out if the same or different types of bacteria live on different parts of our body. I became interested in this project while reading an article about body odor caused by bacteria. I suddenly remembered that each part of our body has a different odor. Under the arms, feet, mouth, and hairs for example each have their own distinct odors. Is this because each part of body is housing a different type of bacteria?

Note: I am not going to identify any bacteria by name. I know that there are millions of different bacteria in the world and many of them are still unknown. I also know that there are different naming conventions for bacteria that well exceed my limitations.

I just want to grow such bacteria and compare them based on their color and colony shape. I am hoping that different bacteria on human body will also have distinct colors and colony shapes.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

The Independent variable is the location on human skin where the bacteria is selected from (head, ears, mouth, under the arms, foot, …).

The dependent variable is the color and shape of bacteria colonies as well as the number of bacteria varieties.

Controlled variable is air (as a possible source of bacteria).

Constants are method, procedures, material and instruments used in experiments.


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.

I think that each part of body has a different type of bacteria and most likely we can only find one type of bacteria in each spot. My hypothesis is based on my previous information about bacteria growth and the conditions that one bacteria becomes the dominant bacteria, depriving others from food and space. I also think that distinct odor of body parts is because such odor is created by certain type of bacteria.

This is another sample hypothesis:

If I collect and grow samples of bacteria from different parts of my body, then bacteria colonies will form that are different in shape or color, showing that they are different bacteria.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Experiment: Comparing the type of bacteria in different locations of body


In this experiment I will collect bacteria samples from my foot, under arms and head and grow them in order to observe and compare the color and shape of bacteria colonies.

Materials Needed are:

  • 6 petri dishes with nutrient agar
  • inoculating loop
  • sterile swaps
  • 2-3 tubes of sterile nutrient broth
  • sterile water
  • Bunsen burners
  • Also required: Incubator set at 35ºC

Where to get the material?

All the required material can be purchased from laboratory suppliers or scientific suppliers. Find them locally by looking in your phone directory. Petri-dishes are more widely available. You can also buy petri-dishes from MiniScience.com or other online suppliers. They are sold separately and they are also included in bacteria growth kits.

Inoculating loop can be built using a thin solid wire. Just form one end of wire to the shape of a ring. It is best if you use a gold or platinum wire for this; however, you can do the same with steel, aluminum and copper wires.

Sterile water can be made by boiling water in a pressure cooker for 10 minutes. If you do not have a pressure cooker, boil water in a kettle for 30 minutes. This is not a perfect solution, but it works good for the purpose of this project.

Any burner that has a gas flame or burns alcohol can be used instead of a Bunsen burner.

Any warm space about 35ºC can be used instead of an incubator. A box or a metal can be painted black and placed under a desk lamp may be used as an incubator. You will need to adjust the distance of the desk lamp until the temperature inside the can stays around 35ºC.


1. The first step is collecting bacteria. To do this, take a sterile cotton swab and carefully rub it against your foot, between your toes. Restrict your sample collection area to the area between two of your toes.
You will later repeat the same process and get bacteria samples from your hear and under your arm.

2. Next, open a plate of nutrient agar and implant your bacteria while isolating them in different concentrations using the following method:

  • Rub the swab over the top third of the plate (see diagram below left). Dispose of the swab.
  • Flame your inoculating loop. Let it cool off. Turn the plate one quarter of a turn. Rub the loop over the plate starting from some point of previous swab. (see diagram below center)
  • Flame your loop again. Let it cool off. Turn the plate another quarter of a turn. Rub the loop over the plate as shown in diagram below right.
  • Label this plate as (foot_1)


3. Open another nutrient agar plate.

  • Without flaming the loop from previous plate, rub it over the top third of the plate (see diagram above left).
  • Flame your inoculating loop. Let it cool off. Turn the plate one quarter of a turn. Rub the loop over the plate starting from some point of previous swab. (see diagram above center)
  • Flame your loop again. Let it cool off. Turn the plate another quarter of a turn. Rub the loop over the plate as shown in diagram above right.
  • Label this plate as (foot_2)

4. Repeat steps 1 to 3 with bacteria samples from your head and under your arms. Name the plates as head_1, Head_2, Armpit_1, Armpit_2.

5. Incubate these plates for 24 hours at 35ºC.

6. Observe and record the size, shape and color of bacteria colonies in each dish.

7. Incubate these plates again for another 24 hours and repeat your observation and recording. You may want to continue incubation and daily observation for up to 7 days.

8. Dispose of all swabs and bacterial cultures.

Learn how to make your own Nutrient Agar plates

Materials and Equipment:

Materials Needed are:

  • 6 petri dishes with nutrient agar. You can buy nutrient agar plates or buy petri-dishes, and make your own nutrient agar.
  • inoculating loop
  • sterile swaps
  • 2-3 tubes of sterile nutrient broth
  • sterile water
  • Bunsen burners
  • Also required: Incubator set at 35ºC

You can purchase nutrient agar plates from different online suppliers. Just search for nutrient agar and find out which of their products is recommended for general bacteria growth experiments. If you like to make your own nutrient agar, click here for sample instructions.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

How many different bacteria did you see in each plate?

Do you see any identical or similar bacteria colony in plates from foot, head and armpit?


No calculation is required.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.