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Microbiology > Baterial Growth, Variation And Metabolism > Flashcards

Baterial Growth, Variation And Metabolism Flashcards

1
Q

All bacteria have three major nutritional needs for growth.

What are these needs❓

A
  1. Carbon (50% dry weight)
  2. Nitrogen (14% dry weight)
  3. Source of energy
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2
Q
  1. Bacteria that are able to growth using CO2 as their sole source of carbon are known as❓
  2. How do they obtain energy❓
A
  1. Lithotrophs/Autotrophs
  2. Photosynthetically (phototrophs)

By oxidation of inorganic compounds (chemolithotrophs)

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3
Q

All bacteria found in humans are❓

A

Heterotrophs

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4
Q

E. coli and pseudomonas aeruginosa grow on the most simple laboratory media

True or false❓
Why❓

A

True

Growth requirements include a wide variety of organic compounds

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5
Q

Haemophilus influenzae and other anaerobes can only be cultured in the lab using❓

Why❓

A
  • Vitamins, purins, pyramidine and hemoglobin supplied in growth medium
  • They need additional growth requirements
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6
Q

Chlamydia sp. cannot be cultured on laboratory medium at all

True or false❓
How are they grown❓

A

True

Must be grown in tissue culture

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7
Q

What is a “minimal” medium❓

A
  • A lab culture media whose contents are simple and completely defined
  • Not usually used in diagnostic micro labs
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8
Q

What is a “nutrient” medium❓

Give examples

A
  • made of extracts of meat or soybeans
  • more complex

•eg nutrient broth, trypticase soy broth

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9
Q

What is a “enriched” medium❓

Give examples

A

•contains added growth factors such as blood, vitamins and yeast extract

•eg blood agar
Chocolate agar

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10
Q

What is a “selective” medium❓

Give examples

A

•contain additives that inhibit the growth of some bacteria but allow others to grow

•MCA:
MacConkey agar
Selective for gram-negative bacteria

•Colistin-nalidixic acid:
Selective for gram-positive bacteria

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11
Q

What do differential mediums do❓

Give an example

A
  • For visualization of metabolic differences between groups or species of bacteria
  • MacConkey agar differentiates between lactose fermenters(pink) and non-lactose fermenters(clear)
  • Blood agar differentiates between hemolytic and non-hemolytic organisms
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12
Q

What is a transport medium used for❓

Give examples

A

•Holding medium designed to preserve the viability of microorganisms in a specimen w/o allowing multiplication

•
Stuart broth
Amies
Cary-Blair

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13
Q

What three factors should be considered for bacterial culture in the lab❓

A

pH

Temperature

Gaseous composition of atmosphere

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14
Q

Diagnostic laboratory media are usually adjusted to a final pH between 7.0 and 7.5

True or false❓
Why❓

A

True

Most pathogenic bacteria grow best at a neutral pH

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15
Q

Psychrophilies are bacteria that❓

A

•grow optimally at 10-20C (cold temp)

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16
Q

Mesophilies are bacteria that❓

A
  • grow optimally at 20-40C (moderate temp)

* most bacteria that have adapted to the human body belong in this category

17
Q

Thermophilies are bacteria that❓

A

•grow optimally at 50-60C (cold temp)

18
Q

Diagnostic laboratories routinely incubate cultures for bacterial growth at ❓

A

35C

19
Q

Fungal cultures are incubated at what temperature❓

A

30C

20
Q

Classify bacteria based on their atmospheric requirements for growth

A

•Obligate aerobes:
require oxygen for growth

•Aerotolerant anaerobes/facultative aerobes:
can survive in the presence of oxygen but do not require it for metabolism eg clostridium spp.

  • Obligate anaerobes: can’t survive in the presence of oxygen
  • Facultative anaerobes: can grow either with or without oxygen
21
Q

There are organisms that grow best when the atmosphere is enriched with extra carbondioxide (5-10%).

What are they called❓
Give an example

A

Capnophilic organisms

Haemophilus influenza

22
Q

Microaerophilic bacteria require a reduced level of oxygen to grow.

Give an example

A

Campylobacter spp.

5-6%

23
Q

Bacteria divide by binary fission. What does “generation time” mean❓

A

The time required for one cell to divide into two cells

24
Q

What is generation time for:

A) E. coli
B) Mycobacterium tuberculosis

A

A) 20minutes

B) 24hrs

25
Q

List the phases of a bacterial growth curve and the corresponding events in those phases

A
  1. Lag phase:
    •preparation to divide
  2. Log phase:
    •logarithmic increase
  3. Stationary phase:
    •limited nutrients/no growth
  4. Death phase:
    •non-viable bacteria>viable bacteria
26
Q

Fermentation is a process of energy production carried out by what group of bacteria❓

The final electron acceptor is❓

A

Obligate and facultative anaerobes

An organic compound

27
Q

The major end product of alcoholic fermentation is❓

A

Ethanol

28
Q
  1. The major end product of homolactic fermentation is❓

2. Give some examples of bacteria that use this pathway

A
  1. Lactic acid
2. Streptococcus genus (all members)
Lactobacillus genus (some members)
29
Q
  1. The major end product of heterolactic fermentation is❓

2. Give some examples of bacteria that use this pathway

A 
1. Lactic acid 
CO2
Alcohol 
Formate 
Acetate
  1. Lactobacillus (some members)
30
Q
  1. The major end product of propionic acid fermentation is❓

2. Give some examples of bacteria that use this pathway

A
  1. Propionic acid
  2. Propionibacterium acnes
    Some anaerobic non-spore forming, gram-positive bacilli
31
Q
  1. The major end product of mixed acid fermentation is❓

2. Give some examples of bacteria that use this pathway

A 
1. 
Lactic 
Acetic 
Succinic  
Formic Acids
  1. Shigella
    Salmonella
    Escherichia
32
Q
  1. The major end product of butanediol fermentation is❓

2. Give some examples of bacteria that use this pathway

A
  1. Acetoin
    2,3-butanediol
  2. Klebsiella
    Enterobacter
    Serratia
33
Q

The EMP/Glycolytic pathway

1) Generates energy in the form of❓
2) Reducing power in the form of❓
3) Anerobic/Anaerobic❓
4) Used by which bacteria❓

A
  1. ATP
  2. NADPH
  3. Anaerobic
  4. Entrobaceriaceae
34
Q

The pentose phosphate/phosphogluconate pathway is used by which bacteria❓

A

Heterolactic fermenting bacteria such a lactobacilli

Brucella abortus

35
Q

The entner-doudoroff pathway

  • uses enterococcusfaecalis
  • is an aerobic pathway

1) True or false❓
2) Mention bacteria that use this mechanism

A

True

Pseudomonas
Alcaligenes

36
Q

An important step in classifying members of the enterobacteriaceae family is the ability of the microorganism to ferment lactose

True or false

A

True

37
Q

In the utilization of lactose by bacteria…

A
  1. Transport of lactose across cell wall into bacterial cytoplasm by beta-galactoside permease
  2. Breakage of galactoside bond to release glucose for fermentation by beta-galactosidase
38
Q

All organisms that can ferment glucose can ferment lactose

True or false

A

False

Quite the contrary

Microbiology (11 decks)

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