Bacteria Lab Images
Halobacterium salinarium x1000
Clostridium perfringens (1000x)
Dichelobacter nodosus (1000x)
@ Joe Rubin
Brachyspira sp (1000x)
Streptococcus canis (1000x)
Micrococcus sp. (1000x)
Back Page
Disk Symbol
CIP
Antibiotic
Ciprofloxacin
Disk Content
5µg
Diameter of Zones of Inhibition (mm)
Resistant
Intermediate
Susceptible
21
NA-30
FM-300
SD
TR
SSS
Nalidixic Acid
Nitrofurantoin
Sulfadiazine
Trimethoprin
Triple Sulfa
30µg
300µg
25µg
5µg
25µg
≤ 13
≤ 14
17
Alcaligenes faecalis
Do not adjust the size of this image when measuring the zones of inhibition- The width of this petri dish in 100mm. The grid lines
are 10mm apart on 100% screen. Ensure you have similar measurements on your screen.
Bacillus subtilis
Do not adjust the size of this image when measuring the zones of inhibition- The width of this petri dish in 100mm.
The grid lines are 10mm apart on 100% screen. Ensure you have similar measurements on your screen.
Anabeana (x500)
Oscillatoria (100x)
https://www.inaturalist.org/observations/62107104
Oscillatoria (400x)
Photo 4294652, (c) Kyle Kerger, some rights reserved (CC BYNC)
Oscillatoria (400x)
Spirulina (at 40, 50x)
Spirulina (100x)
Root nodules (main root shown with an
arrow)
BIOL 124: Organismal biology
Required for Labs
• Make sure you see all Blackboard shells
• WHMIS (SLSO) and BIO safety course
completion (need evidence)
• Use this link to learn more about BB
https://help.blackboard.com/Collaborate/Ultra
collaborate Ultra tutorial video
• share a video in learn.unbc.ca
https://pressbooks.bccampus.ca/unbcstudents/c
hapter/creating-a-video-in-kaltura-mediarecorder/
General Advice
• Read the lab and assignment before the lab
• Take notes during the pre-lab
• Read questions carefully
– Number of marks?
– Title/labels required?
• Pay attention when drawing figures
– If in doubt, include a title and magnification
• Don’t just focus on what’s in the assignment
– “Optional” material fair game for quizzes, etc.
• Study tip- study the images provided (they
represent what you are expect to see in a face to
face course).
Bacteria & Archaea
(Chap 23)
Learning Outcomes
• Identify members of Domains: Archaea and
Bacteria.
• Distinguish member of Domain Bacteria using
several morphological and anatomical structures.
• Identify Gram stained bacteria and explain how
Gram staining works.
• Determine sensitivity of a microbe to a particular
antibiotic using the Kirby Bauer method.
– Explain how bacteria develop resistance to some
antibiotics.
• Key bacteria involved in the nitrogen recycling.
The Three Domains in the Tree
of Life
[Insert Fig. 21.24 on p. 513]
What do you know about these two domains?
How can you distinguish an Archaean from Bacteria?
Fig. 21.24, p. 513
Procedure # 1: Domain Archaea
•Kingdom Archaeabacteria
• Watch video/slide and
identify shape and mobility
•Halobacterium salinarium
Procedure # 2: Domain Bacteria
Kingdom Eubacteria
Prokaryotic Shapes
A few more shapes in your class textbook
Cell Arrangement of Cocci
Diplococci
Streptococci
Tetrad, sarcinae
Staphylococci
Cell arrangement of Bacillus
Staphylobacillus
Cell types-Spirilla
Curved rods e.g. Vibrio cholerae
Helical shape, stiff
e.g., Helicobacter pylori
Helical shape, many curves,
flexible body e.g. Treponema pallidum
http://classes.midlandstech.edu/carterp/courses/bio225/chap04/lecture2.htm
Gram Stain Technique
Come
In
and
Stain
Gram Stain Bacteria
• Gram-positive bacteria
– Appear purple because crystal violet retained
• Gram-negative bacteria
– Appear pink because crystal violet lost
Cell walls in Gram-positive bacteria have extensive
peptidoglycan. Peptidoglycan traps the crystal violet dye.
Gram-positive
cell wall
Polysaccharides
Cell
wall
Peptidoglycan
Plasma
membrane
Protein
Slide 7
Cell walls in Gram-negative bacteria have some
peptidoglycan and an outer membrane.
Gram-negative
cell wall
Polysaccharides
Cell
wall
Outer
membrane
Peptidoglycan
Plasma
membrane
Protein
Table 1.1
Bacterial species
*Stenotrophomonas
maltophilia
Bacillus megaterium
Spirillum volutens
*Streptococcus pyogenes
*Yersinia pestis
Draw a few
bacterium cells
Shape
Cell
Arrangement
Gram Stain
+/-
Diseases
caused
Procedure # 3: Effects of
Antibiotics
• Antibiotic (G): anti =against; bios=life
–Synthetic or natural products.
• Effect on Bacteria
• Kill bacteria (Bactericidal drugs)
• Weaken bacteria-delay or inhibit bacterial
growth and replication (Bacteriostatic)
Antimicrobial Effects
Source: Muheim (2017)
Procedure # 3: Effects of
Antibiotics
• Antibiotic (G): anti =against; bios=life
–Synthetic or natural products.
• Effect on Bacteria
• Kill bacteria (Bactericidal drugs)
• Weaken bacteria-delay or inhibit bacterial
growth and replication (Bacteriostatic)
• Resistant or remain unaffected
–Biggest threat to global health (WHO,
2018)
Mechanisms of Antibiotic Resistance
Watch this video :
Photo courtesy: CDC Public Health Library
Mechanisms of Antibiotic Resistance
Page 546
Classification of Antibiotics
• Narrow spectrum – active against a select group of
bacterial types e.g. gram positive or gram negative.
e.g. Penicillin G (from Penicillin mold),
Bacitracin, Nalidixic acid, Vancomycin etc.
• Broad spectrum- active against a wide range of
bacterial types and may be used to treat a large
number of infections. e.g. Streptomycin, Ampicillin,
Chloramphenicol, Tetracycline, Erythromycin
Ciproflaxin, Novobiacin, Synthetic Penicillins, etc.
Antibiotics Modes of Action
• Inhibit Cell Wall Synthesis and Function:
Penicillin, Bacitracin, Ampicillin, Amoxicillin
• Inhibit Cell Membrane Function: Polymixin B and colistin
• Protein Synthesis Inhibition
– Transcription & Translation
• Erythromycin, Streptomycin, Tetracycline, Chloramphenicol,
Neomycin
• Inhibiting Nucleic Acid (DNA & RNA) Synthesis(Replication & Transcription) e.g. quinolones, rifampin (RNA),
Novobiocin (DNA), Nalidixic acid (DNA), Ciprofloxacin (DNA)
• Metabolic Processes Inhibitors e.g. folic acid
synthesis e.g. sulfanilamide (sulfa drugs), trimethoprim
Ampicillin (AM10)
• Bactericidal
• AM10 –Competitive inhibitor of enzyme
transpeptidease needed to make cell walls.
• It inhibits bacterial cell wall synthesis
(crosslinking of peptidoglycan) by inactivating
transpeptidase on the inner surface of the
bacterial cell membrane.
• Broad spectrum: + and – bacteria
• Able to penetrate the outer layer of Gram
negative bacteria.
• Treats ear and respiratory infections.
Neomycin (N)
• Bactericidal
• Consumed: Oral solution, tablet or topical
cream.
• Broad spectrum antibiotic
• Binds to the 30s subunit of the bacteria
ribosome and 16s rRNA hence it interferes
with mRNA binding and acceptor tRNA
• Treats- eye infections, otitis externa, hepatic
encephalopathy
Nalidixic acid (NA)
• Bactericidal
• Narrow spectrum (limited)- Active
against gram-negative bacteria e.g. E.
coli, Enterobacter spp, Klebsiella and
Proteus mirabilis & vulgaris spp. etc.
• Inhibitor bacterial DNA synthesis
• Binds A subunit of bacterial DNA
gyrase stopping genetic transfer during
conjugation
• Treats all kinds of urinary tract infections
Triple Sulfur (SSS25)
• Broad spectrum
• Bacteriostatic
• A combination drug of three sulfa
antibiotic drugs
• Inhibit dihydropteroate synthases
(DHPS) which critical for folate
synthesis.
Kirby-Bauer Disk Diffusion
Susceptibility Test Protocol
Antibiotic disc
Zone of inhibition
No zone of inhibition
• Used to determine
whether an antibiotic
is effective against a
particular bacteria.
Kirby-Bauer Test Protocol
Zone cannot be
zero = minimum
size of disk.
Antibiotic
disk
Zone of
inhibition
Bacteria
Evaluation of Sensitivity
• Live bacteria specimens
•Bacillus subtilis (+)
•Enterobacter aerogenes (-)
• Measure the zones of inhibition (mm)
• Twice, then average
• Compare your measurement with
Table 48.1-Interprepations of
inhibition zones of test cultures.
Procedure # 4: Cyanobacteria
• Gram negative photoautotrophs
• Plantlike characteristics
• Morphological forms
• Solitary or colonial
• Filamentous
• Observe slides
• Anabaena
• Spirulina
• Merismopedia
Two species of Oscillatoria,
filamentous cyanobacteria (LM)
Procedure # 5: Nitrogen fixing
Bacteria
• Lupines with root
nodules with
Rhizobium spp
• Note:
– Size of nodules
– Distribution of nodules
on the roots and whole
root system
– Number of nodules on
tap/main & lateral roots
Good Drawings
• Proper labels
• Magnification (100x not 100x magnification)
• Figure title goes at the bottom – good descriptive
title. MUST BE > 8 WORDS!
– What makes a good title?
• Genus and species – when handwritten, should
be underlined (otherwise, italics)
– E.g. Dendroctonus ponderosae
• Draw in pencil and use a rule to make lines
• Draw only what you see…not what you think you
should see.
Any Mistakes
Diagram of Anabaena 1000x
• Make sure lines touch the structure
• Draw large enough so that I can make out the differences
• Label from one side if possible
• If you can’t make out a structure, note that in the figure
title (but ask for help first!)
Example of a good diagram
Figure 1. A segment of a living Spirulina. Spirulina are cynanobacteria,
green in colour, with cells longer than they were wider. Photosynthetic plastids
were visible as green dots. Spirulina are found in freshwater and filamentous. 1000x
Example: Combining two specimens in one title
Figure 2. Anatomy of a giant squid (Architeuthis dux) depicting external and internal
features in a) female and b)male specimens.
Concept Maps
Example: Page
302 class
textbook
Figure 1. Concept map showing structural differences between Gram positive
and Gram negative bacteria cell wall and resulting Gram staining.
Concept Maps
• Objective-Organize, elaborate and interpret
knowledge (understanding interrelationships)
• Work from general to specific.
– Main (most important) concept- place this in middle.
– Create a hierarchy of associated concepts – 2nd, 3rd
etc.
– Link these associated concepts to the key concept.
• Within each associated concept- what other key words
are provided?
– Link these words to the associated concepts and to
each other.
– Explaining the connections!
Examples-Linking words
(use common preposition)
• use
• store (s)
• collect
• to become (becomes)
• to
• creates
• to make (makes)
• is absorbed
• holds
• transports (s)
• absorbs
• goes through
• releases
• are
• etc. etc.
• Is a form of
• are found in
• Is made up of
• need
• has, has a
• produce
• have
• goes to
• causes
• combines
• is
• are part of
• Contain(s)
• are a type
Tips for the concept map
• Use all of the words
• Don’t forget about the linking words!
• No “right” answer
• Draw out a rough sketch beforehand
• Make it legible
• Don’t forget a figure title
Assignment!
• Submit one pdf on Blackbaord
(no emailed assignments)
• Hand-in assignment is due
tomorrow at 9am.
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
BIOL 124-Introductory Biology Laboratory II
Summer 2022
Lab # 1
Academic Integrity Statement
In submitting this assignment, I confirm that my conduct during this assignment adheres to the
UNBC Student’s Right & Responsibilities Policy. I confirm that I did NOT act in such a way that
would constitute cheating, misrepresentation, or unfairness, including but not limited to, using
unauthorized aids and assistance, impersonating another person, and committing plagiarism.
Academic Honesty Pledge
I certify that this submitted assignment represents entirely my own efforts and I have neither
given or received unauthorized help on this assignment. I have read and understand the
University of Northern British Columbia’s policies regarding, and sanctions for plagiarism. By
submitting this assignment, I certify that I am acting with academic integrity.
Name:____________________________
Student Number:___________________
Lab section:_______________________
1|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
All drawings must be drawn in pencil, they should be neat and legible and must have a
descriptive title. No shading is allowed. Use a ruler to make straight lines. Ensure your lines
do not cross each other. Watch for plagiarism.
1. Completed Table 1. Use this website https://www.cabi.org/animalscience to find animal
infected these bacteria. Identify at least two animals excluding humans afflicted by these
bacteria. Enter them on the last column. (14 marks)
Table 1.1. Shape, aggregate, and Gram stain of bacteria slides. Include magnification for the
bacteria.
Bacterial species
Cell Arrangement
Gram
(Include
all stain +/arrangements
present) Put an *
on the most
common
arrangement
Spherical Tetrad,
Positive
staphylococcus*
Chicken
and dogs
Spiral
Single*
Pigs and birds
Clostridium perfringens
Rod-like
shape
Chains, pairs and Positive
singles*
Sheep
and horses
Dichelobacter nodosus
Rod-like
shpe
pairs
Negative
Goats and cattle
Streptococcus canis
spherical Chain
positive
Cats and dogs
Micrococcus spp
(identify the species
used for the animal
column)
Brachyspira spp
Draw a few
bacteria cells
or one
complete
organism.
Bacteria
shape
Negative
Animals
(identify the species
used for the animal
column)
2|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
a) c (9 marks)
To which Domain do they belong? What is their shape? What is their color?
2. Draw a few cells showing shape and cell arrangement of Streptococcus canis. Add a
descriptive and informative title the diagram. Answer these questions associated with the
slide/diagram. (8 marks)
i) Which part of the bacterium is stained by the Gram staining procedure?
ii) What is the resulting color after adding safranin?
iii) What is the resulting color after adding crystal violet dye?
3|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
3. Examine Table 1.1 and answer the following questions. Underline all scientific names. (8
marks)
i) Which bacteria have similar Gram stain as Streptococcus canis but different cell shape?
ii) Which bacteria have similar cell shape as Streptococcus canis but different Gram Stain?
iii) Which bacteria are different in both the Gram stain and cell shape when compared to
Streptococcus canis? Name the cell shape and Gram stain of bacteria identified.
iv) List all bacteria that have a fairly small layer of peptidoglycan.
4. In the space below, provide diagrams of Anabaena and Oscillatoria. For Anabaena, show
the cell wall, vegetative cells (photosynthetic cells) and heterocyst. For the Oscillatoria
show cell wall, cytoplasm, filament. Add a descriptive and informative title. (10 marks)
i) Which of these two organisms is able to fix nitrogen? Which structure present in the slide
allows them to fix nitrogen? Briefly describe this structure. (3 marks)
4|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
ii) Describe the appearance of the trichomes (thread of cells) for each organism. How are they
similar? In what ways do they differ? (3 marks)
5. Answer the following questions and base your answers only on what saw on images provided.
If a characteristic is not present or does not apply, use N/A. Give this chart a descriptive and
informative title. (20 marks)
Characteristic
Halobacterium
salinarium
Streptococcus Anabeana
canis
Oscillatoria
Domain
Kingdom
Mode of nutrition
Major component of
the cell wall
Individual cell shape
Filamentous with no
specialized cells or
branches (yes or no)
Filamentous
with
specialized cells but no
branches (yes or no)
Filamentous
with
specialized cells and
branches (yes or no)
Potential Gram stain
colour if staining is
performed
6. Antibiotic Sensitivity Test. Determine the zones of inhibition derived for these two bacteria.
Use the Kirby Chart provided to determine sensitivity as resistant (R), intermediate (I) or
5|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
susceptible (S) of the two bacteria plates provided. Add a descriptive and informative title
to this table and write scientific names properly. Note: Measure the disks as they appear at
100% (i.e. as uploaded and your screen is set at 100%. Do not reduce or enlarge them,
otherwise your zones will be wrong. (13 marks)
Bacteria
Name
Plate
#
Disk Names
Size
(mm)
Sensitivity
Size
(mm)
Sensitivity
Size
(mm)
Sensitivity
Size
(mm)
Sensitivity
1
1
a) Referring to the table above, answer the following questions: (4 marks) (Note sensitivity
means that the bacteria have intermediate or susceptible zones of inhibition). List all
antibiotic(s).
The gram positive bacteria were sensitive to which antibiotic(s)?
The gram positive bacteria were resistant to which antibiotic(s)?
The gram negative bacteria were sensitive to which antibiotic(s)?
The gram negative bacteria were resistant to which antibiotics(s)?
b) Which antibiotic was most effective against both bacteria? How can you tell? Provide
numerical data to support your answer. (2 marks)
c) Which bacteria were resistant to a large number of antibiotics? How can you tell? Provide
numerical data to support your answer. (2 marks)
d) Theoretically, the antibiotic that disrupts cell wall synthesis used in this lab is supposed to be
very effective on all bacteria. Which antibiotic is this? Does your data support this statement?
Why or why not? Explain your answer. (4 marks)
6|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
e) Does the data support the statement that “a larger zone of inhibition mean that the antibiotic
is more effective when compared to another antibiotic which has a small zone on the same
bacteria”? Use data to support your explanation. (3 marks)
f) Does the data support the statement that “a larger zone of inhibition of an antibiotic mean
that this antibiotic is more effective compared to a small zone of the same antibiotic on the
same bacteria”? Provide data to support your explanation. (3 marks)
g) Antibiotics that target cell wall synthesis have no negative effects on the cells of the
mammalian host. Why? (2 marks)
7. Broad spectrum antibiotics that are bactericidal are supposed to be equally effective on both
gram-positive and gram-negative bacteria.
a) Which antibiotics used in this lab fall under this category? List all of them. (2 marks)
b) Does the data you collected support the above statement? Why or why not? Provide data
to support your explanations. (2 marks)
c) What is the mode of action of Nalidixic acid? Did it perform as expected in both bacteria?
What did you expect? Why or why not? Provide data to support your answer. (3 marks)
7|P a g e
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
8. Getting to know you. Submit a 90 seconds (11/2 minutes) video not only to introduce yourself
(include your face) but to help me understand who you are. Additionally, what did you like the
most about this lab exercise? What did you learn? What were the two take home messages
from this lab? Save your video in any of these two formats: .MOV or .MP4. Upload the video on
Blackboard as a separate upload from your assignment. Please review how to submit video
assignment: https://pressbooks.bccampus.ca/unbcstudents/chapter/submitting-anassignment/. (10 marks)
8|P a g e
Purchase answer to see full
attachment
Halobacterium salinarium x1000
Clostridium perfringens (1000x)
Dichelobacter nodosus (1000x)
@ Joe Rubin
Brachyspira sp (1000x)
Streptococcus canis (1000x)
Micrococcus sp. (1000x)
Back Page
Disk Symbol
CIP
Antibiotic
Ciprofloxacin
Disk Content
5µg
Diameter of Zones of Inhibition (mm)
Resistant
Intermediate
Susceptible
21
NA-30
FM-300
SD
TR
SSS
Nalidixic Acid
Nitrofurantoin
Sulfadiazine
Trimethoprin
Triple Sulfa
30µg
300µg
25µg
5µg
25µg
≤ 13
≤ 14
17
Alcaligenes faecalis
Do not adjust the size of this image when measuring the zones of inhibition- The width of this petri dish in 100mm. The grid lines
are 10mm apart on 100% screen. Ensure you have similar measurements on your screen.
Bacillus subtilis
Do not adjust the size of this image when measuring the zones of inhibition- The width of this petri dish in 100mm.
The grid lines are 10mm apart on 100% screen. Ensure you have similar measurements on your screen.
Anabeana (x500)
Oscillatoria (100x)
https://www.inaturalist.org/observations/62107104
Oscillatoria (400x)
Photo 4294652, (c) Kyle Kerger, some rights reserved (CC BYNC)
Oscillatoria (400x)
Spirulina (at 40, 50x)
Spirulina (100x)
Root nodules (main root shown with an
arrow)
BIOL 124: Organismal biology
Required for Labs
• Make sure you see all Blackboard shells
• WHMIS (SLSO) and BIO safety course
completion (need evidence)
• Use this link to learn more about BB
https://help.blackboard.com/Collaborate/Ultra
collaborate Ultra tutorial video
• share a video in learn.unbc.ca
https://pressbooks.bccampus.ca/unbcstudents/c
hapter/creating-a-video-in-kaltura-mediarecorder/
General Advice
• Read the lab and assignment before the lab
• Take notes during the pre-lab
• Read questions carefully
– Number of marks?
– Title/labels required?
• Pay attention when drawing figures
– If in doubt, include a title and magnification
• Don’t just focus on what’s in the assignment
– “Optional” material fair game for quizzes, etc.
• Study tip- study the images provided (they
represent what you are expect to see in a face to
face course).
Bacteria & Archaea
(Chap 23)
Learning Outcomes
• Identify members of Domains: Archaea and
Bacteria.
• Distinguish member of Domain Bacteria using
several morphological and anatomical structures.
• Identify Gram stained bacteria and explain how
Gram staining works.
• Determine sensitivity of a microbe to a particular
antibiotic using the Kirby Bauer method.
– Explain how bacteria develop resistance to some
antibiotics.
• Key bacteria involved in the nitrogen recycling.
The Three Domains in the Tree
of Life
[Insert Fig. 21.24 on p. 513]
What do you know about these two domains?
How can you distinguish an Archaean from Bacteria?
Fig. 21.24, p. 513
Procedure # 1: Domain Archaea
•Kingdom Archaeabacteria
• Watch video/slide and
identify shape and mobility
•Halobacterium salinarium
Procedure # 2: Domain Bacteria
Kingdom Eubacteria
Prokaryotic Shapes
A few more shapes in your class textbook
Cell Arrangement of Cocci
Diplococci
Streptococci
Tetrad, sarcinae
Staphylococci
Cell arrangement of Bacillus
Staphylobacillus
Cell types-Spirilla
Curved rods e.g. Vibrio cholerae
Helical shape, stiff
e.g., Helicobacter pylori
Helical shape, many curves,
flexible body e.g. Treponema pallidum
http://classes.midlandstech.edu/carterp/courses/bio225/chap04/lecture2.htm
Gram Stain Technique
Come
In
and
Stain
Gram Stain Bacteria
• Gram-positive bacteria
– Appear purple because crystal violet retained
• Gram-negative bacteria
– Appear pink because crystal violet lost
Cell walls in Gram-positive bacteria have extensive
peptidoglycan. Peptidoglycan traps the crystal violet dye.
Gram-positive
cell wall
Polysaccharides
Cell
wall
Peptidoglycan
Plasma
membrane
Protein
Slide 7
Cell walls in Gram-negative bacteria have some
peptidoglycan and an outer membrane.
Gram-negative
cell wall
Polysaccharides
Cell
wall
Outer
membrane
Peptidoglycan
Plasma
membrane
Protein
Table 1.1
Bacterial species
*Stenotrophomonas
maltophilia
Bacillus megaterium
Spirillum volutens
*Streptococcus pyogenes
*Yersinia pestis
Draw a few
bacterium cells
Shape
Cell
Arrangement
Gram Stain
+/-
Diseases
caused
Procedure # 3: Effects of
Antibiotics
• Antibiotic (G): anti =against; bios=life
–Synthetic or natural products.
• Effect on Bacteria
• Kill bacteria (Bactericidal drugs)
• Weaken bacteria-delay or inhibit bacterial
growth and replication (Bacteriostatic)
Antimicrobial Effects
Source: Muheim (2017)
Procedure # 3: Effects of
Antibiotics
• Antibiotic (G): anti =against; bios=life
–Synthetic or natural products.
• Effect on Bacteria
• Kill bacteria (Bactericidal drugs)
• Weaken bacteria-delay or inhibit bacterial
growth and replication (Bacteriostatic)
• Resistant or remain unaffected
–Biggest threat to global health (WHO,
2018)
Mechanisms of Antibiotic Resistance
Watch this video :
Photo courtesy: CDC Public Health Library
Mechanisms of Antibiotic Resistance
Page 546
Classification of Antibiotics
• Narrow spectrum – active against a select group of
bacterial types e.g. gram positive or gram negative.
e.g. Penicillin G (from Penicillin mold),
Bacitracin, Nalidixic acid, Vancomycin etc.
• Broad spectrum- active against a wide range of
bacterial types and may be used to treat a large
number of infections. e.g. Streptomycin, Ampicillin,
Chloramphenicol, Tetracycline, Erythromycin
Ciproflaxin, Novobiacin, Synthetic Penicillins, etc.
Antibiotics Modes of Action
• Inhibit Cell Wall Synthesis and Function:
Penicillin, Bacitracin, Ampicillin, Amoxicillin
• Inhibit Cell Membrane Function: Polymixin B and colistin
• Protein Synthesis Inhibition
– Transcription & Translation
• Erythromycin, Streptomycin, Tetracycline, Chloramphenicol,
Neomycin
• Inhibiting Nucleic Acid (DNA & RNA) Synthesis(Replication & Transcription) e.g. quinolones, rifampin (RNA),
Novobiocin (DNA), Nalidixic acid (DNA), Ciprofloxacin (DNA)
• Metabolic Processes Inhibitors e.g. folic acid
synthesis e.g. sulfanilamide (sulfa drugs), trimethoprim
Ampicillin (AM10)
• Bactericidal
• AM10 –Competitive inhibitor of enzyme
transpeptidease needed to make cell walls.
• It inhibits bacterial cell wall synthesis
(crosslinking of peptidoglycan) by inactivating
transpeptidase on the inner surface of the
bacterial cell membrane.
• Broad spectrum: + and – bacteria
• Able to penetrate the outer layer of Gram
negative bacteria.
• Treats ear and respiratory infections.
Neomycin (N)
• Bactericidal
• Consumed: Oral solution, tablet or topical
cream.
• Broad spectrum antibiotic
• Binds to the 30s subunit of the bacteria
ribosome and 16s rRNA hence it interferes
with mRNA binding and acceptor tRNA
• Treats- eye infections, otitis externa, hepatic
encephalopathy
Nalidixic acid (NA)
• Bactericidal
• Narrow spectrum (limited)- Active
against gram-negative bacteria e.g. E.
coli, Enterobacter spp, Klebsiella and
Proteus mirabilis & vulgaris spp. etc.
• Inhibitor bacterial DNA synthesis
• Binds A subunit of bacterial DNA
gyrase stopping genetic transfer during
conjugation
• Treats all kinds of urinary tract infections
Triple Sulfur (SSS25)
• Broad spectrum
• Bacteriostatic
• A combination drug of three sulfa
antibiotic drugs
• Inhibit dihydropteroate synthases
(DHPS) which critical for folate
synthesis.
Kirby-Bauer Disk Diffusion
Susceptibility Test Protocol
Antibiotic disc
Zone of inhibition
No zone of inhibition
• Used to determine
whether an antibiotic
is effective against a
particular bacteria.
Kirby-Bauer Test Protocol
Zone cannot be
zero = minimum
size of disk.
Antibiotic
disk
Zone of
inhibition
Bacteria
Evaluation of Sensitivity
• Live bacteria specimens
•Bacillus subtilis (+)
•Enterobacter aerogenes (-)
• Measure the zones of inhibition (mm)
• Twice, then average
• Compare your measurement with
Table 48.1-Interprepations of
inhibition zones of test cultures.
Procedure # 4: Cyanobacteria
• Gram negative photoautotrophs
• Plantlike characteristics
• Morphological forms
• Solitary or colonial
• Filamentous
• Observe slides
• Anabaena
• Spirulina
• Merismopedia
Two species of Oscillatoria,
filamentous cyanobacteria (LM)
Procedure # 5: Nitrogen fixing
Bacteria
• Lupines with root
nodules with
Rhizobium spp
• Note:
– Size of nodules
– Distribution of nodules
on the roots and whole
root system
– Number of nodules on
tap/main & lateral roots
Good Drawings
• Proper labels
• Magnification (100x not 100x magnification)
• Figure title goes at the bottom – good descriptive
title. MUST BE > 8 WORDS!
– What makes a good title?
• Genus and species – when handwritten, should
be underlined (otherwise, italics)
– E.g. Dendroctonus ponderosae
• Draw in pencil and use a rule to make lines
• Draw only what you see…not what you think you
should see.
Any Mistakes
Diagram of Anabaena 1000x
• Make sure lines touch the structure
• Draw large enough so that I can make out the differences
• Label from one side if possible
• If you can’t make out a structure, note that in the figure
title (but ask for help first!)
Example of a good diagram
Figure 1. A segment of a living Spirulina. Spirulina are cynanobacteria,
green in colour, with cells longer than they were wider. Photosynthetic plastids
were visible as green dots. Spirulina are found in freshwater and filamentous. 1000x
Example: Combining two specimens in one title
Figure 2. Anatomy of a giant squid (Architeuthis dux) depicting external and internal
features in a) female and b)male specimens.
Concept Maps
Example: Page
302 class
textbook
Figure 1. Concept map showing structural differences between Gram positive
and Gram negative bacteria cell wall and resulting Gram staining.
Concept Maps
• Objective-Organize, elaborate and interpret
knowledge (understanding interrelationships)
• Work from general to specific.
– Main (most important) concept- place this in middle.
– Create a hierarchy of associated concepts – 2nd, 3rd
etc.
– Link these associated concepts to the key concept.
• Within each associated concept- what other key words
are provided?
– Link these words to the associated concepts and to
each other.
– Explaining the connections!
Examples-Linking words
(use common preposition)
• use
• store (s)
• collect
• to become (becomes)
• to
• creates
• to make (makes)
• is absorbed
• holds
• transports (s)
• absorbs
• goes through
• releases
• are
• etc. etc.
• Is a form of
• are found in
• Is made up of
• need
• has, has a
• produce
• have
• goes to
• causes
• combines
• is
• are part of
• Contain(s)
• are a type
Tips for the concept map
• Use all of the words
• Don’t forget about the linking words!
• No “right” answer
• Draw out a rough sketch beforehand
• Make it legible
• Don’t forget a figure title
Assignment!
• Submit one pdf on Blackbaord
(no emailed assignments)
• Hand-in assignment is due
tomorrow at 9am.
LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
BIOL 124-Introductory Biology Laboratory II
Summer 2022
Lab # 1
Academic Integrity Statement
In submitting this assignment, I confirm that my conduct during this assignment adheres to the
UNBC Student’s Right & Responsibilities Policy. I confirm that I did NOT act in such a way that
would constitute cheating, misrepresentation, or unfairness, including but not limited to, using
unauthorized aids and assistance, impersonating another person, and committing plagiarism.
Academic Honesty Pledge
I certify that this submitted assignment represents entirely my own efforts and I have neither
given or received unauthorized help on this assignment. I have read and understand the
University of Northern British Columbia’s policies regarding, and sanctions for plagiarism. By
submitting this assignment, I certify that I am acting with academic integrity.
Name:____________________________
Student Number:___________________
Lab section:_______________________
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
All drawings must be drawn in pencil, they should be neat and legible and must have a
descriptive title. No shading is allowed. Use a ruler to make straight lines. Ensure your lines
do not cross each other. Watch for plagiarism.
1. Completed Table 1. Use this website https://www.cabi.org/animalscience to find animal
infected these bacteria. Identify at least two animals excluding humans afflicted by these
bacteria. Enter them on the last column. (14 marks)
Table 1.1. Shape, aggregate, and Gram stain of bacteria slides. Include magnification for the
bacteria.
Bacterial species
Cell Arrangement
Gram
(Include
all stain +/arrangements
present) Put an *
on the most
common
arrangement
Spherical Tetrad,
Positive
staphylococcus*
Chicken
and dogs
Spiral
Single*
Pigs and birds
Clostridium perfringens
Rod-like
shape
Chains, pairs and Positive
singles*
Sheep
and horses
Dichelobacter nodosus
Rod-like
shpe
pairs
Negative
Goats and cattle
Streptococcus canis
spherical Chain
positive
Cats and dogs
Micrococcus spp
(identify the species
used for the animal
column)
Brachyspira spp
Draw a few
bacteria cells
or one
complete
organism.
Bacteria
shape
Negative
Animals
(identify the species
used for the animal
column)
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
a) c (9 marks)
To which Domain do they belong? What is their shape? What is their color?
2. Draw a few cells showing shape and cell arrangement of Streptococcus canis. Add a
descriptive and informative title the diagram. Answer these questions associated with the
slide/diagram. (8 marks)
i) Which part of the bacterium is stained by the Gram staining procedure?
ii) What is the resulting color after adding safranin?
iii) What is the resulting color after adding crystal violet dye?
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
3. Examine Table 1.1 and answer the following questions. Underline all scientific names. (8
marks)
i) Which bacteria have similar Gram stain as Streptococcus canis but different cell shape?
ii) Which bacteria have similar cell shape as Streptococcus canis but different Gram Stain?
iii) Which bacteria are different in both the Gram stain and cell shape when compared to
Streptococcus canis? Name the cell shape and Gram stain of bacteria identified.
iv) List all bacteria that have a fairly small layer of peptidoglycan.
4. In the space below, provide diagrams of Anabaena and Oscillatoria. For Anabaena, show
the cell wall, vegetative cells (photosynthetic cells) and heterocyst. For the Oscillatoria
show cell wall, cytoplasm, filament. Add a descriptive and informative title. (10 marks)
i) Which of these two organisms is able to fix nitrogen? Which structure present in the slide
allows them to fix nitrogen? Briefly describe this structure. (3 marks)
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
ii) Describe the appearance of the trichomes (thread of cells) for each organism. How are they
similar? In what ways do they differ? (3 marks)
5. Answer the following questions and base your answers only on what saw on images provided.
If a characteristic is not present or does not apply, use N/A. Give this chart a descriptive and
informative title. (20 marks)
Characteristic
Halobacterium
salinarium
Streptococcus Anabeana
canis
Oscillatoria
Domain
Kingdom
Mode of nutrition
Major component of
the cell wall
Individual cell shape
Filamentous with no
specialized cells or
branches (yes or no)
Filamentous
with
specialized cells but no
branches (yes or no)
Filamentous
with
specialized cells and
branches (yes or no)
Potential Gram stain
colour if staining is
performed
6. Antibiotic Sensitivity Test. Determine the zones of inhibition derived for these two bacteria.
Use the Kirby Chart provided to determine sensitivity as resistant (R), intermediate (I) or
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
susceptible (S) of the two bacteria plates provided. Add a descriptive and informative title
to this table and write scientific names properly. Note: Measure the disks as they appear at
100% (i.e. as uploaded and your screen is set at 100%. Do not reduce or enlarge them,
otherwise your zones will be wrong. (13 marks)
Bacteria
Name
Plate
#
Disk Names
Size
(mm)
Sensitivity
Size
(mm)
Sensitivity
Size
(mm)
Sensitivity
Size
(mm)
Sensitivity
1
1
a) Referring to the table above, answer the following questions: (4 marks) (Note sensitivity
means that the bacteria have intermediate or susceptible zones of inhibition). List all
antibiotic(s).
The gram positive bacteria were sensitive to which antibiotic(s)?
The gram positive bacteria were resistant to which antibiotic(s)?
The gram negative bacteria were sensitive to which antibiotic(s)?
The gram negative bacteria were resistant to which antibiotics(s)?
b) Which antibiotic was most effective against both bacteria? How can you tell? Provide
numerical data to support your answer. (2 marks)
c) Which bacteria were resistant to a large number of antibiotics? How can you tell? Provide
numerical data to support your answer. (2 marks)
d) Theoretically, the antibiotic that disrupts cell wall synthesis used in this lab is supposed to be
very effective on all bacteria. Which antibiotic is this? Does your data support this statement?
Why or why not? Explain your answer. (4 marks)
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
e) Does the data support the statement that “a larger zone of inhibition mean that the antibiotic
is more effective when compared to another antibiotic which has a small zone on the same
bacteria”? Use data to support your explanation. (3 marks)
f) Does the data support the statement that “a larger zone of inhibition of an antibiotic mean
that this antibiotic is more effective compared to a small zone of the same antibiotic on the
same bacteria”? Provide data to support your explanation. (3 marks)
g) Antibiotics that target cell wall synthesis have no negative effects on the cells of the
mammalian host. Why? (2 marks)
7. Broad spectrum antibiotics that are bactericidal are supposed to be equally effective on both
gram-positive and gram-negative bacteria.
a) Which antibiotics used in this lab fall under this category? List all of them. (2 marks)
b) Does the data you collected support the above statement? Why or why not? Provide data
to support your explanations. (2 marks)
c) What is the mode of action of Nalidixic acid? Did it perform as expected in both bacteria?
What did you expect? Why or why not? Provide data to support your answer. (3 marks)
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LAB 1- BACTERIA & ARCHAEA- ASSIGNMENT
8. Getting to know you. Submit a 90 seconds (11/2 minutes) video not only to introduce yourself
(include your face) but to help me understand who you are. Additionally, what did you like the
most about this lab exercise? What did you learn? What were the two take home messages
from this lab? Save your video in any of these two formats: .MOV or .MP4. Upload the video on
Blackboard as a separate upload from your assignment. Please review how to submit video
assignment: https://pressbooks.bccampus.ca/unbcstudents/chapter/submitting-anassignment/. (10 marks)
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