A Survey of Microorganisms: Bacteria and Protists
Background:
The Kingdom Protista is made up of a variety of eukaryotic, unicellular organisms, which are sometimes
referred to as protozoans or algae. Some of these single-celled organisms are capable of making their own
food by photosynthesis. Others have developed methods of ingesting food by means of specialized organelles.
(Some protists have both autotrophic and heterotrophic capabilities) Protists have a variety of appearances
and methods of locomotion.
Materials Needed:
Live Cultures
Bacterial Cultures: Cyanobacteria (photosynthetic)
1. Nostoc
2. Oscillatoria
3. Anabeana
4. Lactobacilli (from Milk Kefir)
Protozoan (animal-like protists) Cultures:
1. Amoeba (Phylum Sarcodina-Amoeboids)
2. Paramecium (Phylum Ciliophora-Cilliates)
Algae (plant-like protists) Cultures:
1. Peridinium (Phylum Pyrrophyta-Dinoflagellates)
2. Synedra (Phylum Chrysophyta-Golden Algae)
3. Euglena (Phylum Euglenophyta-Euglenoids)
4. Green Algae: (Phylum Chlorophyta)
a. Volvox
b. Spirogyra
Lab Equipment: depression slides, cover slips, dropper pipettes, compound light microscopes, prepared
slides (do not put live specimen samples on the prepared slides…use the blank depression slides)
Special Note:
All cultures are located at the supply table in the corner of the lab. Do not cross contaminate cultures. Use only
the properly designated pipettes for each culture.
This lab is made up of Four Main Sections, which can be
done in any order. In order to avoid extra waiting time, it is
a good idea to not work on the same section of the lab
that other groups near you are doing. You may begin
with any of the four sections.
Section I: Bacteria
1. Prepared Slides: Start by familiarizing yourself with
the microscope by viewing some prepared slides
of bacteria. Identify whether they are gram (-/+)
and how they would be classified (shape and
grouping)
2. Using the designated pipette, prepare a wet mount
slide of the cyannobacteria, Anabaena.
3. Using the designated pipette, prepare a wet mount
slide of the cyannobacteria, Osciliatoria by placing
a couple of drops onto a glass slide and place a
cover slip over the drops.
4. Lactobacilli – Obtain a small drop of Milk Kefir and smear it on a slide (regular) with a toothpick for 2-3
seconds. Place a very small drop of Methyl blue stain on the slide and cover with the cover slip.
5. Look at the prepared slide of the cyannobacteria, Nostoc (at the supply table) I will set up the slide…
Section II: Protozoans (Animal-Like Protists)
Amoeba (Phylum Sarcodina - Amoeboids) Large; colorless; no definite shape; move slowly by
pseudopods) Look Like blobs…not the speedy little protists…that’s food.
1.
Prepare a wet mount slide of the Amoeba culture by placing a couple of drops from the amoeba
culture into a clean depression slide. Place a cover slip over the depression and observe using your
microscope.
2.
3.
4.
5.
Find the amoeba under low power and observe it. Reduce the light by adjusting the diaphragm.
(You may want to use medium power so that the amoeba fills up a large portion of the field of view.
This will depend on the size of the amoeba that you are observing.) Watch the amoeba for signs of
movement.
Sketch the amoeba in the first circle below. Wait about one minute, then sketch it again in the
second circle. Wait again, and then carefully draw the amoeba in the third circle.
Label each drawing with arrows to show the direction that the cytoplasm was flowing.
The amoeba’s contains a clear circle known as the contractile vacuole. Look at your amoeba and
try to find what looks like a small, clear bubble inside.
6. To eat, an amoeba uses its pseudopods to trap and
engulf food. When it has eaten, a food vacuole is formed.
Look at the amoeba in the microscope, and try to find a
vacuole with material inside. (Do not confuse it with the
nucleus, which is the largest dark object in the amoeba.)
7. Use the following terms to Label figure 14.1 below:
nucleus, food vacuole, pseudopodia, contractile vacuole,
ectoplasm, endoplasm, plasma membrane.
8. On your third drawing of the amoeba above, try to
identify and label as many of the following structures as
possible: pseudopodia, nucleus, cell membrane, cytoplasm,
contractile vacuole and food vacuole.
9. When finished, dump your slide contents into the sink,
wash and move to another section.
Paramecium (Phylum Ciliophora - Cilliates): Medium size; clear; slipper-shaped; move quickly by use of
cilia. These move pretty fast. Stay on scanning until you find one or two. You can try to increase magnification,
but they move out of the screen pretty fast.
1. Use the dropper in the paramecium culture to get a drop of “scum” out of the container, and place it on
a microscope slide. Add one drop of methyl cellulose on top of the paramecium (this is a “syrup” to slow
down the organisms). Place a cover slip on top of the mixture. Have to share…only one bottle
2. Find a paramecium under low power and observe it. Then, change to medium power to see the details
of the paramecium better. Reduce the light by adjusting the diaphragm. You may need to move the
slide to keep the paramecium in the field of view.
3. Carefully draw the paramecium in the circle below.
4. The paramecium’s contractile vacuoles appear as star shaped structures at each end. Try to find the
contractile vacuoles in your specimen.
5. To eat, a paramecium collects food in its oral groove. When it has eaten, a food vacuole is formed.
Look at the paramecium in the microscope, and try to find a vacuole with material inside. (Do not
confuse it with the nucleus, which is the largest dark object in the paramecium.)
6. On the diagram below, label the following structures: cilia, nucleus, pellicle, cytoplasm,
contractile vacuole, food vacuole, gullet, oral groove, macronucleus, and micronucleus. You
may want to reference your lab manual to help (p. 115-116
7. On your drawing of the paramecium above, try to identify
and label as many of the following structures as you can: cilia,
nucleus, pellicle, cytoplasm, contractile vacuole and food vacuole.
8. When finished, wash the paramecium down the drain. Wash and dry your slide and cover slip.
Section III: Algae (Plant-Like Protists)
Euglena (Phylum Euglenophyta - Euglenoids): small; green; oval; move quickly by flagellum (hard to see the
flagellum, but should be able to see most everything else.)
1. Use the dropper in the euglena culture to get a drop out of the container, and place it on a depression
slide. Place a cover slip on top of the drop.
2. Find euglena under low power and observe them. Shift to high power, and get a closer look. Carefully
draw a few euglena in the circle below.
3. The euglenas’ chloroplasts appear as green objects inside the cells. Euglenas make their own food by
photosynthesis, but may also eat if they choose to.
4. Label the diagram of the Euglena to the right using the following terms: eyespot, flagellum, chloroplast,
reservoir, nucleus, pellicle, cell membrane, and contractile vacuole.
5. On your drawing of the euglena above, try to identify and label as many of the following structures as
you can: flagellum, nucleus, cell membrane, & cytoplasm (use figure 14.9 on p.119 to help you identify
the parts correctly.)
6. Wash the euglenas down the drain. Wash and dry the slide and
cover slip.
Peridinium (Phylum Pyrrophyta - Dinoflagellates): characterized by the presence of “armored” cell plates
(see figure 14.7 on p. 118) and two flagella - one directed posteriorly and the other laterally. (may not be able
to see the flagella, but should be able to see the “plates” that make up the body.)
1. Use the dropper in the Peridinium culture to get a drop out of the container, and place it on a
depression slide. Place a cover slip on top of the drop.
2. Find a Peridinium under low power and then switch to higher power to get a closer look. Carefully draw
a Peridinium in the circle below.
3. On your drawing, note the cellulose plates that make up the cell wall and try to identify and illustrate the
transverse and longitudinal grooves in which the two flagella lie. (use figure 14.6 on p.118 to help you
identify these characteristics).
4. Wash the peridinium down the drain. Wash and dry the slide and cover slip.
Synedra (Phylum Chrysophyta - Golden Algae – Diatoms)
1. Use the dropper in the Syndedra culture to get a drop out of the container, and place it on a depression
slide. Place a cover slip on top of the drop. (May be hard to see on high power…kind of small.)
2. Find a Synedra under low power and then switch to higher power to get a closer look. Carefully draw a
Synedra in the circle below.
3. Is this diatom a solitary diatom or does it form colonies? ___________________________
4. Wash the Synedra down the drain. Wash and dry the slide and cover slip.
Green Algae (Phylum Clorophyta)
1. Obtain a sample of the colonial algae, Volvox and the filamentous green algae, Spirogyra.
2. Draw the two samples in the circles below. (gotta get a bit of the brown/green stuff in the pipette)
Volvox
Spirogyra
5. Make an Inference…why do you think Spirogyra is called “Spirogyra”?