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Bacteriology > Bacterial Metabolism > Flashcards

Bacterial Metabolism Flashcards

1
Q

Name features that distinguish prokaryotes from eukaryotes

A

Prokaryotes have:

  • A single, circular chromosome instead of a nucleus with multiple chromosomes
  • No nuclear membrane or mitotic apparatus
  • Transcription coupled to translation.
  • Ribosome is 70S instead of 80S; moderate differences in shape and function. Target for antimicrobial agents.
  • Cell Wall with unique residues and structural organization. Target for antimicrobial agents
  • Simple cytosolic organizations: no endoplasmic reticulum, mitochondria or other organelles; bacteria have a complex plasma membrane
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2
Q

What is the fundamental unit of taxonomy

A

species

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3
Q

Describe the species boundaries/definition in eukaryotes

A
  • sharp natural species boundaries

- Species are defined by the ability to produce fertile offspring

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4
Q

Describe the species boundaries/definition in prokaryotes

A
  • no sharp natural species boundary

- Species defined by genetic relatedness and possession of similar physiological function

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5
Q

Describe multiplication in prokaryotes. what is this called

A

Multiplication is asexual, where each individual cell gives rise to two identical offspring-binary fission

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6
Q

Molecular identification of bacteria

A

Relationships among bacteria are reflected in their DNA composition

  • amplification techniques
  • genome analysis and sequencing techniques
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7
Q

Advances over current classical molecular techniques for molecular identification of bacteria are

A
  • automation (productivity)
  • speed (rapid)
  • greater accuracy (fewer false positives)
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8
Q

Polymerase chain reaction (PCR)

A

-Amplification of pathogen specific DNA (potential for rapid identification)
*identify slow growing- or non-cultivable- bacteria
*Rapid identification (Example, amplify the gene encoding Clostridium
difficile toxin from stool of an individual with antibiotic-associated
pseudo-membrane enterocholitis

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9
Q

Restriction fragment length polymorphism (RFLP)

A

Analysis of restriction endonuclease patterns of the bacterial chromosome
-Used during hospital acquired (nosocomial) infections to determine the
source of an infection

example: During a bacterial infection
-(RFLP of isolates are identical between patient and personnel) bacterium infecting
patients hospital associated: single source (personnel) of infection)

-(RFLP of isolates are different between patient and personnel) Infection community
associated from multiple sources

-this doesn’t show causal associations but does show temporal
• hospital associated and community acquired infections are often treated
differently

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10
Q

What is a good way to identify liptospira

A

Analysis of unbiased next-generation DNA sequencing of the host tissue
(cerebrospinal fluid)

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11
Q

identification of a prokaryotic species based on biochemical and biological methods (Morphology)

A

Morpholgy:

  • colony morphology
  • cell shape, gram stain, motility (leptospira)
  • presence of capsules

Biochemical:

  • ability to metabolize specifici substrates
  • -production of specific end products
  • antibiotic sensitivity
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12
Q

overview of metabolism

A

Glucose is converted to pyruvate which

  • in the presence of oxygen can metabolized via respiration into CO2 and H2O. This process is energy efficient.
  • in the absence of oxygen is metabolized to organic end products. This has little energy production and is uniques to microbes (aka diagnostic)
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13
Q

Whether a bacteria does respiration or fermentation depends on what

A

-the ability of the organism to metabolize oxygen

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14
Q

aerobes

A

metabolize O2; grow only in its presence

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15
Q

Microaerophiles

A

metabolize O2; grow only in low O2

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16
Q

Facultative anaerobes

A

metabolize O2 in the presence of O2; ferment in the absence (metabolically diverse)

17
Q

Aerotolerant

A

do not metabolize O2; but ferment in the presence or absence of O2

18
Q

Anaerobes

A

do not metabolize O2; do not grow in the presence of O2 (gut bacteria)

19
Q

OXIDASE TEST

A

Differentiates aerobes from facultative anaerobes:

  • Aerobes (Pseudomonas aeruginosa) use Cytochrome C as the terminal oxidase.
  • Facultative anaerobes (Escherichia coli) use Cytochrome D as terminal oxidase
  • In the OXIDASE TEST: Cytochrome C oxidase reacts with indicator compounds upon this oxidation reaction (scored as a change in color, blue)

So if it is an aerobe it will appear blue

20
Q

Why is fermentation diagnostic

A

because fermentations are unique to species of bacterium

21
Q

Mixed Acid Fermentation: Enterobacteriaceae

A

-DIAGNOSTIC KNOW THIS

  • Glucose is converted to pyruvate via glycolysis
  • pyruvate is broken down to lactate and acetate and CO2.
  • pyruvate is also broke down to formate which via NADH2 to NADH is converted to ethanol

under acidic conditions: Formate vai formate dehydrogenase is converted to CO2 and H2 (so gas is produced) this can be used as a diagnostic test bc E. coli and Salmonella convert formate to Co2 and H2 but Shigella and S. typhi do not. SO you can grow it in a test tube and look for gas

22
Q

-3 key points about Fermentation

A
  1. each fermentation gives the bacterium a selective advantage in the environment
  2. use for targeting of anti-microbial agents
    - diagnostic
23
Q

4 phases of bacterial growth

A
  1. lag-NO cell division: adaptation; increased metabolism
  2. Exponential: Balanced growth
  3. Stationary: decrease nutrients, pH change, buildup of toxic end products
  4. Death: eventual, slope varied with species
24
Q

List the types of bacteria based on how much they like to grow in oxygen, starting from least to greatest

A 
obligate anaerobes
aerotolerant anaerobes
facultative anaerobes 
microaerophiles
obligate anaerobes
25
Q

What temp range are most pathogens able to grow in and what are organism that grow in this temp range called

A

Mesophilic
Range: 10-45
Optimum: 20-40

26
Q

pathogenic bacteria usually grow between what pHs

A

7.2 and 7.6

27
Q

osmotic conditions

A
    • most bacteria tolerate only moderate salt
      concentrations.
  • Halophilic are an exception
  • Isolated from high salt environments (salt flats)
  • Require up to 30% salt for growth
    (5. 0 M NaCl equivalent)

-osmotic sensitivy can be used for selection of microbes

28
Q

Describe the selective media Mannitol salt media

A

7.5% NaCl- Selects for Gram positive, by
inhibition of growth of Gram negative

so if something grows on mannitol salt media then it must be gram positive

29
Q

Instead of entering the death phase of the life cycle, some bacteria can

A
  • go from a vegetative cell to a spore

- most bacteria die with prolonged exposure to the stationary phase, unless the for a spore

30
Q

Sporulation

A
  • unique property of a subset of bacteria:
  • Bacillus (G+ aerobe)
  • Clostridium (G+ anaerobe)
  • Response due to ↓ in supply C, N, or P
  • Spore -Dormant structure capable of survival for prolonged periods; with capacity to reestablish the vegetative life style
  • example of unicellular differentiation
31
Q

Spore

A

-Dormant structure capable of survival for prolonged periods; with capacity to reestablish the vegetative life style

32
Q

Three steps of sporulation

A
  • DNA synthesis
  • asymmetric cell division
  • DNA packaging
33
Q

describe spores and staining

A

spore is refractive to stains

34
Q

germination

what is it and what is required

A
  • when a spore becomes a vegetative cell
  • spores may remain dormant for 100s of years and then with water and metabolites (amino acid, sugar) they can become vegetative cells again
35
Q

How to inactivate spores

A
  • they are EXTREMELY heat resistant.
  • You must autoclave them
  • Wet heat, 120 degrees celcius for 20 minutes
  • autoclave sterilizes

Bacteriology (15 decks)

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