Introduction to Microbiology
Where do Microorganisms come
from?EVERYWHERE!!!!They are all around us, in this lab
we will examine various microorganisms in the environment around us.
Part I-Test Tube
Obtain a test tubeFill 1/4 full with soilAdd water to test tube until it is
about 1/3 full. Cap test tube and shake.
Place your names on the label.
Part I- Petri Dish
Obtain a petri dish and place your names on the label.
Pour a layer of hot, melted agar into the petri dish. Fill your petri dish about 1/4th full.
Recover your petri dish.Allow the agar to harden for about 5
minutes.
Locate a sterile transfer loop.Place the plate in front of you.Dip the loop end of the transfer loop into
the soil water and transfer the soil water to the agar plate.
Gently rub the surface of the agar with loop. Don’t push too hard.
Transfer two more loopsful of soil water in the same manner.
Observe your plate and make a drawing of what you see.
Part II- Fungi
Obtain another petri plate, and put a label with your names.
Add a thin layer of tomato soup to the bottom of the plate.
Grind up a small sample of dirt in your fingers.Sprinkle a few specks of dirt on the soup and
cover the plate.Observe your plate and make a drawing of
what you see.
Part III- Yeast test tube
Obtain a culture tube, and label with your names.
Add yeast growth medium to the tube until it is 2/3 full.
Locate the packet of dry yeast.Add one of the small particles of yeast to the
tube.Shake the tube with the top on until you can’t
see the particles of yeast any longer.
Part III- Yeast Slide
Obtain a sterile loop.Dip the end of the loop into the yeast liquid in the
tube.Transfer a small amount of liquid onto a clean glass
slide.Repeat this 4 more times so you have a drop of the
yeast growth medium on the slide.Add a cover slip and observe the yeast under high
power on a microscope.Count the number of cells you see in the field.
Part IV- Algae and Protozoa
Locate the large plastic bottle filled with pond water.
Obtain a clear glass slide and a cover slip. Place a drop of pond water on the slide
using a pipette.Place cover slip on slide.Observe under low and medium power.Make drawings.
Part V- Soil CultureObtain your original tube containing the soil
and water after about 4 days. Obtain a clear glass slide, a cover slip, and the
bottle of methylene blue stain. Transfer a drop of soil water to the slide.Spread the water around on the slide.After the water has dried, add a drop of the
methylene blue stain, and let it dry for 1 minute on the slide.
Carefully blot the slide dry with a paper towel.Observe the slide under high and low power.Make drawings of what you see.