1. Lab 2
Microbiology 2421

2. Quiz 2
• What technique uses a inoculating loop?
• What is a colony?

3. Quiz 2
• What technique uses a inoculating loop?
• Streaking for isolation
• What is a colony?
• Is a large number of bacteria that are deverive
from one cell.

4. Facebook page
• TAMUK elementary microbiology 2421
• http://www.facebook.com/pages/TAMUK-
Elementary-Microbiology-
2421/153699168102827?ref=hl

5. Facebook page

6. acidithiobacillus ferrooxidans

7. • What disease(s) does S. pyogenes cause?
Strep throat,Flesh eating bacteria, scarlet fever
• Which species uses mannitol?
• Staphylococcus aureus
• Where are these species found normally?
Skin, environment of high saline.
• What is the special name for organisms that like
or tolerate higher concentrations of salt in the
environment? halophile

8. • 3. Based on your observations, how did an increase in the magnification
(when you changed the objective) change your light requirements? Did
you need more or less light at 100X compared to 10X? What is the
purpose of the iris diaphragm?
• You needed more light. Iris diaphragm is used to control the amount of
light.
• 4. What is the resolution of the microscope? List 2 ways to increase the
resolution of your microscope
• Resolution is the ability of a microscope to distinguish two entities as
separate bodies. Increase magnification, or add oil immersion
• 5. Why did you add oil to observe the specimens at 100X? How does it
help you view the specimens?
Oil is used to act as glass it doesn’t hit air which will allow it to refract.
Instead the oil allows for less refraction more light to enter the objective
lens. It allows more light which allows more light separate the objects
making a clear image.

9. • 6. What type of stain was used in the preparation of the slides?
(simple, differential)
both simple as where all the bacteria where the same color. And
differential where the bacteria where different color due to the
bacteria having a structure that changes the color of the stain.
Example the gram stain
• 7. What is a basic stain? What is an acidic stain? Which type was
used in the prepared slides you viewed?
A basic stain is a stain that binds to the bacteria it self due to the (-)
charge of the cell it self which attracts the stain(bacteria cells are
colored). A Acidic stain is one that binds to the slide and colors
everything except the organism itself. Creating clear light which
allows light to pass in. last week we viewed a basic stain.

10. • 8. What does “parfocal” mean? Is the microscope used in the laboratory a
“parfocal” microscope?
Parfocal is that a microscope stays in focus when you change the objective lens.
• The teaching assistant introduced themselves to you and explained some of the
safety issues that are specific for our laboratory. The following questions are based
on this information.
• 9. What is the name of your TA? Cameron Martin
• 10. If you need to find your TA, in what laboratory would you find him/her?
214
• 11. If you break a slide, where do you put it?
• The blue / White broken glass bin
• 12. What type of trash goes in the orange/red plastic bag in the front of the
laboratory?
biological waste

11. • 13. Where is the emergency shower?
• The far right of the room
• 14. What does “MSDS” mean?
• Material safety data sheets
• 15. Where are the MSDS found?
In the back left cabinet

12. Todays lab
• The aim of this exercise is to isolate individual
colonies(colony) so that a pure culture can be
started.
• Two methods that will be used today are
spread plate and streaking for isolation.

13. How to use a pipette men

14. Spread plate technique
• I will make the wands for each groups
• This procedure uses dilutions to isolate
bacteria.
• After diluting the bacteria plate the bacteria
by pipetting 100ul on the nutrient agar plate.
• Only the last 2 dilutions shall be plated.
• The last 2 dilution will dilute the bacteria
10,000 and 1,000,000

15. Spread plate technique
dip loop Flame
In ethanol
Then twist the loop on the plate
To separate cells and create lawns

16. Streaking for isolation technique
This technique uses a inoculating loop to spread
the bacteria. By spreading the bacteria this
dilutes the bacteria and makes pure colonies.
The first part is to flame you loop then let It cool
and stick it in the ependorf.
From here you will begin you first spread interval
this will go in a line and swing around this will be
done 3 time.
After each “spread” the loop has to be flamed with
the Bunsen burner, then spread.
There should be about 3 spread intervals.

17. Streaking for isolation

18. Spread plate technique.

19. Last step
• After your done with the spread plate and the
streaking for isolation technique place you
plates in the incubator an wait until next week
to look at your colonies.

20. Next week
• Next week part 3 will be completed after the
organism have grown up
• Read for next week lab quiz.