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Microbiology > Lecture 6 - Microbial Growth > Flashcards

Lecture 6 - Microbial Growth Flashcards

1
Q

Binary Fission

A

bacterial cell division/reproduction

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2
Q

Generation Time

A

the length of time it takes for 1 round of binary fission

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3
Q

Generation Time of E. coli

A

20 min

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4
Q

Who discovered biofilms?

A

Anton van Leeuwenhoek

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5
Q

Plaque that grows on teeth is an example of a ________.

A

Biofilm

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6
Q

Quorum Sensing

A

refers to how bacteria communicate with eachother and coordinate behavior (incl. use of nutrients) within the matrix of the biofilm

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7
Q

A microbe in a biofilm is ____ times more resistant to antimicrobials than microbes not in biofilms.

A

1000

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8
Q

Which endospore microbe caused food poisoning and tragically killed several at a dinner party?

A

Clostridum botulinum

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9
Q

4 Factors Influencing the Growth of Microbes

A
  • Temp
  • pH
  • Osmolarity (tonicity)
  • Salinity
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10
Q

Salinity

A

concentration of salt in a solution

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11
Q

Microbe that Causes Botulism

A

Clostridium botulinum

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12
Q

What can survive the high temps of canning?

A

Endospores

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13
Q

Dented or bloated cans of canned food could be indicative of possible ____________.

A

Botulism

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14
Q

Should canned foods be stored in hot areas?

A

No.

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15
Q

Temperature can affect a microbe’s _______.

A

Rate of Growth

*Note: different types of microbes grow faster at different temperatures depending on the type

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16
Q

Psychrophiles

A

microbes found in very cold/polar regions

(peak rate of growth at ~10 C)

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17
Q

Room Temp in degrees Celsius

A

~20

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18
Q

Body Temp in degrees Celsius

A

37

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19
Q

Psychotrophs

A

microbes that grow well at cooler temps and room temp and are primarily responsible for spoiling food

(peak rate of growth around room temp 20 C)

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20
Q

Mesophiles

A

microbes that grow well between 10-50 C

(mesophiles grow particularly well at body temp of 37 C)

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21
Q

Thermophiles

A

microbes that grow well in the heat

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22
Q

Extreme Thermophiles

A

microbes that grow well in extreme heat near boiling

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23
Q

-phile

A

loving; likes

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24
Q

alkalin

A

basic
(pH greater than 7)

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25
Q

acidophile

A

acid loving bacteria which grow well in acid environents with a pH less than 7

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26
Q

neutrophiles

A

bacteria that grow best in environments closer to a neutral pH of 7

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27
Q

alkalinophiles

A

bacteria that grow best in basic environments with pH greater than 7

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28
Q

buffers

A

maintain pH of a culture

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29
Q

Peptone

A

A cheap, rough buffer made from dehydrated animal protein that has been digested w/ enzymes

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30
Q

Na2HPO4

A

disodium phosphate
used as a buffer

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31
Q

KH2PO4

A

monopotassium phosphate
used as a buffer

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32
Q

halophiles

A

GreatSaltLake&DeadSea

microbes that like salty environments

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33
Q

-static or -stasis

A

stop/stand still

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34
Q

-cidal

A

to kill

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35
Q

Microbial Growth

A

an increase in the number of cells

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36
Q

Does Clostridium botulinum prefer environments with high or low oxygen concentration?

A

Low Oxygen

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37
Q

Acidic foods generally taste ___.

A

sour

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38
Q

Basic foods generally taste ____.

A

bitter

39
Q

Why does “salting” help preserve food?

A

Salting creates an extremely hypertonic environment which draws the water out of and consequently kills the microbes

40
Q

the tonicity of an environment affects _____.

A

osmotic pressure

41
Q

What is the maximum percent of agar you can have in a culture medium?

A

1.5%

(No more than 1.5 g of agar per 100 mL of solution)

42
Q

OBLIGATE Halophiles

A

REQUIRE environments with a high salt concentration

43
Q

FACULTATIVE Halophiles

A

microbes that can withstand an environment with high salt concentrations but do not require the salt to survive

44
Q

Why do microbes need Carbon and Oxygen?

A

all organic compounds require C & H

45
Q

Why do microbes need nitrogen?

A

Nitrogen is found in nucleic acids such as DNA, RNA, ATP.

Nitrogen is part of chlorophyll in photosynthetic microbes.

46
Q

Why do microbes need sulfur?

A

Sulfur is required make certain amino acids for proteins, vitamins and lipids.

47
Q

Why do microbes need phosphorus?

A

Phosphorus is found in nucleic acids such as DNA, RNA & ATP.

Phosphorus is needed to make phospholipids and form the cell membrane.

48
Q

Do all microbes require oxygen?

A

No. Only microbes that do aerobic cellular respiration and need the oxygen to act as the terminal electron acceptor.

49
Q

Why do microbes need trace elements such as K, Fe, Mg, Ca, Zn?

A

to act as enzyme cofactors

50
Q

SOD

A

Superoxide Dismutase

51
Q

Function of SOD?

A

Superoxide Dismutase is an enzyme to neutralize potentially toxic forms of oxygen.

52
Q

Name 3 Obligate Aerobes

A
  • Bacillus pseudomonas
  • Bacillus aeruginosa
  • Mycobacterium tuberculosis
53
Q

Name one genus of Obligate Anaerobes

A

Clostridium

54
Q

Do obligate anaerobes produce catalase?

A

No

55
Q

Do obligate anaerobes produce SOD?

A

No

56
Q

Name two types of Facultative Anaerobes

A
  • E. Coli
  • Salmonella
57
Q

Name genus of Aerotolerant Anaerobes

A

Lactobacillus

58
Q

Name a type of Microaerophile

A

Listeria monocytogenes

59
Q

Is Listeria Gram-Positive or Gram-Negative?

A

Gram-Positive

60
Q

How many flagella does listeria have?

A

one

(monotrichous)

61
Q

What type of infection is flu?

A

a respiratory infection

62
Q

Gastroenteritis is often referred to as “the Stomach Flu” but is it a flu?

A

No, because flu is a respiratory infection and not a GI infection.

63
Q

Common Symptoms of Gastroenteritis

A

diarrhea, stomach cramps, nausea, vomiting

64
Q

turbidity

A

cloudiness seen in culture mediums that are growing bacteria

65
Q

Microaerophile

A

requires oxygen but only in low concentrations

66
Q

Agar

A

Made from red algae/red seaweed and is often used in culture mediums and used to create semi-solid surface for microbes to grow on.

67
Q

inoculum

A

the microbes placed in a medium to grow

68
Q

inoculate

A

the act of placing inoculum in a growth medium

69
Q

Slant

A

When agar is used in a test tube rather than a plate and is allowed to solidify at an angle within the test tube

70
Q

Why not use jello and gelatin instead of agar?

A
  • Gelatin liquifies at a lower temp.
  • Gelatin is easily broken down by enzymes produced by the bacteria.
71
Q

Difference between a Chemically-Defined and a Complex Medium

A

Chemically defined mediums are expensive and the exact chemical composition of the medium is known in order to grow specific microbes.

Meanwhile Complex Mediums Are cheaper and the chemical composition varies between batches. Complex Mediums are more generic and are used to grow a variety of microbes.

72
Q

Selective Medium

A

Medium containing inhibitory ingredients to prevent the growth of unwanted microbes but allows the growth of desired microbes

73
Q

Common Method to Make a Medium Selective

A

add antibiotics to the medium

74
Q

Differential Medium

A

make it easier to distinguish colonies of different organisms on the plate

75
Q

Blood Agar is a commonly used ______ Medium.

A

Differential

76
Q

Blood Agar is often used to distinguish hemolytic and non-hemolytic colonies of what type of bacteria?

A

Streptococcus

77
Q

Group A Streptococci are hemolytic or non-hemolytic?

A

Hemolytic

78
Q

Name 3 illnesses Streptococcus pyrogenes can cause

A
  • Strep Throat
  • Impetigo
  • Necrotizing Fasciitis
79
Q

Is MacConkey Agar a differential or selective medium?

A

Both

80
Q

What is the purpose of the Streak Plate Method when inoculating a plate?

A

the purpose is to ultimately end up with colonies composed of only one species that originated from a single microbe.

81
Q

Should you freeze your cultured plate to preserve the microbes?

A

No, because freezing will cause water crystals to form inside the microbes and will destroy them from the inside out.

Although, Deep Freezing with liquid nitrogen can be a long-term storage method.

82
Q

Lyophilization AKA

A

Freeze-Drying

83
Q

What are the 4 Phases of Microbial Growth?

A
  • Lag Phase
  • Log Phase
  • Stationary Phase
  • Death Phase
84
Q

Lag Phase

A

Microbes are getting ready to divide but population growth has not yet occurred

85
Q

Log Phase

A

exponential growth of microbes as the population increases

86
Q

Stationary Phase

A

Nutrient in the medium are being used up and the rate of growth is the same as the rate of microbe deaths so the overall population of microbes remains approximately the same

87
Q

Death Phase

A

nutrients are used up and microbes are dying off

88
Q

If a microbe is viable, it is _____.

A

Living

89
Q

What method would you use to determine the number of viable (living) cells in a culture)

A

Plate Count or Serial Dilution

90
Q

What method would you use to determine the total number of cells in a culture?

A

Filtration and Direct Microscopic Count

91
Q

When doing a Serial Dilution, which plate would you use to determine the number of microbes?

A

The plate with 30-300 colonies

(If multiple plates have 30-300 colonies, use the one as closest to 300)

92
Q

Coulter Counters

A

Direct Electronic Counting of microbes in a suspension

93
Q

Spectrophotometers

A

Measures the amount of light passing through a tube with microbes growing in it versus a tube with no microbes (the blank). The more microbes in the tube, the less light will pass through.

Microbiology (22 decks)

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