Module 10 W

You can use the culture characteristics of bacterial grwoth patterns in broth culture to learn about

• Oxygen requirements 

• Hydrophobicity 

• Motility 

Turbid

an evenly dispersed homogenous growth in a broth

sediment or pellets

cells that grow or sink to the bottom of the tube

pellicle

growth at the broth-air interface at the top of the broth tube

Obligate aerobe

grows only at the surface

microaerophilic

grows just below the surface

Facultative anaerobe

Grows throughout but greatest growth at the surface

aerotolerant anaerobe

grows with or without oxygen. Disperated equally throughout the medium

Obligate anaerobe

grows only at the bottom

Say what type of grow each is

1. Obligate aerobe

2. Microaerophile

3. Facultative anaerobe

4. Aerotolerant anaerobe

5. Obligate anaerobe

How may colonies vary 

color, shape, elevation, and more 

What can contaminate a bacteriology media

fungal growth

why is it unadvised to open the top if you suspect mold growing

it can release reproductive spores on the fungus which can be carried on for long distances on air currents

How does non-pigmented bacterial colonies look

translucent, tan, cream, or white in apperance

How do pigmented colonies appear?

red, golden yellow, or blue-green.

the colors in bacterial colonies can indicate

potential pathogens

Pigments can be 

diffusible or non-diffusible 

diffusible pigments

spread from colony into colony in surrounding agar medium

non diffusible pigment

stay within colonies

Say the following about bacillus subtilus 

Growth Medium: 

Pigment: 

is it diffusible or not

Unique growth characteristics: 

Oxygen characteristics: 

Growth medium: Broth and Agar plate/slant 

Pigment: Cream white (no pigment) 

Diffusible/non-diffusible: N/A 

Unique growth characteristics: Irregular 
Oxygen characteristics: Aerobic and can form pellicle

Say the following about Staphylococcus epidermidis 

Growth Medium:  

Pigment:

is it diffusible:

Oxygen characteristics:

Growth Medium: Broth/Agar plate

Pigment: None (but can appear yellow)

is it diffusible: N/A

 Oxygen characteristics: Faculative anaerobe

Say the following about: Micrococcus Luteus 

Growth Medium:

Pigment:

is it diffusible:

Oxygen characteristics:

Growth Medium: Agar plate

Pigment: Yellow

is it diffusible: non-diffusible

Oxygen characteristics: Obligate aerobe 

Say the following about: Serratia Marcescens 

Growth Medium:

Pigment:

is it diffusible:

Oxygen characteristics:

Growth medium: Agar plates (25-30*C) 

Pigment: Red (prodigiosin) 

Is it diffusible: non diffusible 

Oxygen characteristic: Facultative anaerobic 

Say the following about: Pseudomonas Aeruginosa 

Growth Medium:

Pigment:

is it diffusible:

Oxygen characteristics:

Growth medium: Agar plate/Slant 

Pigment: green-blue pigment 

Is it diffusible: Diffusible 

Oxygen characteristic: Facultative anaerobe or aerobic. Fruity grape-like odor 

Say the following about: Group A streptococcus pyogenes

Growth Medium:

Pigment:

is it diffusible:

Oxygen characteristics:

Growth medium: agar or blood agar 

Pigment: No pigment (but medium can be red) 

is is it diffusible: N/A 

Oxygen characteristics: Facultative anaerobic

What are the unique oders that microorganisms can produce

• Pleasant grape like (pseudomonas aeruginosa)

• Rotten egg smell of hydrogen sulfide

• Sour smell of kitchen dish/sour milk from the growth of staphylococcus

Why do some colonies have a rotten egg smell of hydrogen sulfide

Produced when sulfate serves as a final electron acceptor in the electron transport system during anaerobic respiration

Two pathogenic bacteria that cause the most disease in humans are 

streptococcus pyogenes and staphlycoccus aureus 

What is pseudomonas aeruginosa

opportunistic pathogens that causes infections in health care settings

Where does pseudomonas aeruginosa grow in

Moist enviroments

What diseases can pseudomonas aeruginosa cause 

• Infection of burn victims because the primary skin barrier is destroyed (serous fluid produced) 

• Cystic fibrosis 

• blue-green pus of wounds 

diseases caused by streptococcus pyogenes (name 3)

• Streptococcal pharyngitis (strep throat)

• Acute rheumatic fever and heart disease

• Toxic shock syndrome

What is staphylococcus aureus known as

staph

diseases cause by staphylococcus aureus 

• foodborn intoxication 

• Cutaneous infections (impetigo, boils, wound infection) 

• Toxic shock syndrome, scalded skin syndrome 

• Bacteremia and metastatic infections 

Mutualism

metabolic products that can be beneficial

parasitism

metabolic products that can be detrimental

What does the term hydrophobicity 

the property of a substance to repel water and resist dissolving in it 

Give two reasons why bacterial cells may grow only at the bottom of a broth tube, growth known as sediment or pellet

1. The bacterial is an obligate anaerobic organism

2. They are heavy/non-motile and sink

How are cell morphology and culture morphology differentiated from each other?

Cell morphology describes the shape and arrangement of individual bacterial cells under a microscope after staining while cultural morphology describes the appearance of a bacterial colony or culture growing on a solid or liquid media

Would you expect the same organism, grown for the same amount of time on the same agar plate medium to produce colonies of approximately the same size?

Not allows. Even though its the same organism/medium, the location and crowding affect colony size

If all colonies were well isolated, how would that affect the size of the colonies

colonies would be approximately the same size because each one has equal access to nutrients, space, and oxygen

What happens if the colonies are growing very close to one another? 

Colonies would be smaller because they are competing for limited nutrients and oxygen 

Would you expect to observe a difference in size, dependent upon where the bacterium is growing on the plate? Why or why not?

Yes colonies near the center or in crowded areas will usually be smaller due to higher competition and waste build up. Colonies at the edges tend to be larger since they have more access to fresh nutrients

When many colonies grow closely together, what gets ‘used up’ and what ‘builds up’ in the microenvironment around the bacteria?

gets sed up: Nutrients, oxygen, and space

Builds up: Waste products, toxins, and acidic byproducts of metabolism

Define morphology 

The appearance and structure of a cell 

What is a pellicle and what type of microorganism would grow as a pellicle

A pellicle are cells near the broth air interface. Microorganisms that are aerobic grow like this like bacillus

What would spreading growth on an agar slant signify about an organism

the motility of the organism

Give two examples of pigmented organisms 

• serratia marcescens 

• Pseudomonas aeruginosa 

On the slant, bacillus subtilis often exhibits what type of growth

obligate aerobic

pinpoints (punctiform colonies) are indicative of what type of bacteria

Streptococcus

If you have a pure culture growing on an agar plate, which of the following would you expect to be true?

• Well-isolated colonies (CFUs) should be about the same size as colonies that are growing

very close together. (Yes or No)

• Well-isolated colonies (CFUs) should be larger than colonies that are growing very close

together. (Yes or No)

• Well-isolated colonies (CFUs) should be smaller than colonies that are growing very close

together. (Yes or No)

• No  

• Yes

• No

Pseudomonas fluorescens

pigment:

disease:

light bluish/greenish fluorescence stronger

Bloodstream and respiratory infection

Mycobacterium makes what in broth

pellicle