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Veterinary Microbiology > Microbial Growth 2.0 > Flashcards

Microbial Growth 2.0 Flashcards

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1
Q

what is the purpose of culture media?

A

we need to grow, transport, and store microorganisms in the lab

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2
Q

how is culture media sold (2 ways)

A
  1. solid
  2. liquid
    preparations
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3
Q

what must culture media contain?

A

all nutrients an organism requires for growth

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4
Q

how are culture media classified? (3 ways)

A
  1. by chemical constituents
  2. by physical nature
  3. by function
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5
Q

when classifying based on chemical constituents, what are the 2 types of culture media?

A
  1. defined/synthetic

2. complex

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6
Q

describe defined/synthetic media

A

each ingredient can be defined with a chemical formula

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7
Q

describe complex culture media

A

contain some ingredients of unknown chemical composition (like beef broth)

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8
Q

when classifying based on physical nature, what are the 3 types of culture media?

A
  1. liquid
  2. semisolid
  3. solid
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9
Q

when classifying based on function, what are the 4 types of culture media?

A
  1. supportive (general purpose)
  2. enriched
  3. selective
  4. differential
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10
Q

list and describe 3 additional media components

A
  1. peptones: protein hydrolysates from protein sources
  2. extracts: aqueous extracts, usually beef or yeast
  3. agar: sulfated polysaccharide solidifying agent
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11
Q

why is agar such a common media component?

A

most microbes can’t degrade it

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12
Q

what do supprotive or general purpose media do? what are they generally used for?

A

support the growth of many microorganisms, to identify microorganisms generally

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13
Q

give two examples of supportive or general culture media

A
  1. TSB: tryptic soy broth

2. TSA: tryptic soy agar

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14
Q

describe enriched media, such as blood agar

A

general purpose media supplemented with special nutrients

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15
Q

define selective media

A

allow for/select for the growth of particular microorganisms while inhibiting the growth of others
GROWTH/NO GROWTH

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16
Q

give an example of a selective media

A

MacConkey agar selects for gram-negative bacteria, gram-positive bacteria won’t grow on this agar

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17
Q

describe differential media

A

distinguishes among different groups of microbes and even permits tentative ID based on biological characteristics
(COLOR CHANGE)

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18
Q

does a plate have to be either selective OR differential?

A

no, some plates can do both

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19
Q

give an example of a differential media

A

blood agar distinguishes between hemolytic versus nonhemolytic bacteria

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20
Q

give an example of a plate that is BOTH selective AND differential

A

MacConkey agar again! It distinguishes between lactose fermentors versus nonlactose fermentors (lactose fermentors turn red as digest lactose)

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21
Q

describe fastidious microbes

A

need specific nutrient supplements to grow

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22
Q

what type of growth will fastidious microbe exhibit of general plates?

A

slow growth

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23
Q

describe facultative microbes

A

have a preference of aerobic versus anaerobic, but can grow in either aerobic or anaerobic conditions,

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24
Q

give an example of facultative microbes

A

rumen microbes

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25
Q

how can you recreate anaerobic conditions in a lab for anaerobic or facultative anaerobic microbes?

A

can use chambers or whole fancy systems

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26
Q

what is isolation of a pure culture? who developed this technique/idea (hint: this was part of his postulates)

A

a population of cells arising from a single cell; developed by Robert Koch

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27
Q

what does isolation of pure cultures allow for?

A

the study of a single type of microorganism in mixed culture

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28
Q

what are the 3 techniques used to isolate pure cultures?

A
  1. streak plate
  2. spread plate
  3. pour plate
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29
Q

describe the streak plate method

A

involves spreading a mixture of cells on an agar surface so that individual cells are well separated from each other; use an inoculating loop or swab

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30
Q

what is the end result of the streak plate method?

A

each cell can reproduce to form a separate colony

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31
Q

what is a colony?

A

a visible growth or cluster or microorganisms

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32
Q

describe the spread plate method

A

a small volume of diluted mixture containing approximately 25-250 cells is transferred and spread evenly over surface with a sterile bent rod

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33
Q

describe the pour plate method

A
  1. sample is serially diluted
  2. diluted samples are mixed with liquid agar
  3. mixture of cells and agar are poured into sterile culture dishes
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34
Q

when is the pour plate method good to use? why?

A

with a soil sample that had a lot of microbes on it; allows you to dilute down to count and pour onto plate

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35
Q

what is continuous culture of microorganisms?

A

growth in an open system with continual provision of nutrients and continual removal of wastes

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36
Q

what does continuous culture of microorganisms do to cells?

A

maintains cells in log phase at constant biomass concentration of extended periods

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37
Q

how is continuous culture of microorganisms achieved?

A

by using a continuous culture system

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38
Q

describe a continuous culture system

A
  1. constant supply of cells in exponential phase growing at a known rate
  2. study of microbiral growth at very low concentrations, close to those present in natural environment
  3. study of interactions of microbes under conditions resembling those in aquatic environments
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39
Q

when is a continuous culture system often used? (2)

A
  1. food and industrial microbiology

2. to study rumen microbes

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40
Q

what are the 2 measures of microbial growth?

A
  1. can measure changes in NUMBER of cells in a population

2. cam measure changes in MASS of population

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41
Q

what is the more specific measure of microbial growth?

A

direct measurement of cell numbers

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42
Q

what are the 2 ways of measuring cell numbers?

A

direct and viable cell counts

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43
Q

what are the 4 methods to measure cell numbers directly?

A
  1. counting chambers
  2. on membrane filters
  3. flow cytometry
  4. electronic counters- the Coulter counter
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44
Q

give a pro and con about the method of counting chambers to measure cell numbers

A

pro: easy, inexpensive, quick
con: cannot distinguish between living adn dead cells

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45
Q

does counting chambers to measure cell number give information about size and morphology of the microorganisms?

A

yes

46
Q

give 2 examples of counting chambers to measure cell numbers

A
  1. hematology lab from anatomy and physiology

2. fecal egg counts

47
Q

what is flow cytometry?

A

microbial suspension forced through small orifice with a laser beam

48
Q

give a pro of using flow cytometry to measure cell numbers

A

can count cells of differing size, internal complexity, and other characteristics within a population

49
Q

can you tell live vs dead cells using flow cytometry and electronic counters?

A

yep

50
Q

do electron counters yield as much information when counting cells as flow cytometry?

A

nah

51
Q

what is the con of using methods such as flow cytometry and electronic counters to measure cell numbers?

A

expensive, need the equipment and then maintenance of that equipment

52
Q

describe the spread plate method to measure cell numbers

A

a diluted sample of bacteria is spread over solid agar surface or mixed with agar and poured on a petri plate, incubated and then COLONIES are counted

53
Q

what is counted with the spread plate method?

A

COLONIES, not cells

54
Q

what is a CFU?

A

colony forming unit, counted when using the spread plate method

55
Q

give a pro and a con of using the spread plate method to measure cell numbers

A

pro: easy, common
con: can’t determine specific number of cells, just CFUs

56
Q

what are the 3 ways to measure cell mass?

A
  1. dry weight
  2. spectrophotometry
  3. concentration of a particular cell constituent
57
Q

describe dry weight as a way to measure cell mass

A

time consuming and not very sensitive (not super informative)

58
Q

describe spectrophotometry as a way to measure cell mass

A

amount of light scattering is directly proportional to cell biomass

59
Q

describe concentration of a particular cell substituent as a way to measure cell mass

A

can measure concentration of chlorophyll, DNA, ATP, or a protein; is useful if amount of each cell is constant

60
Q

in what conditions do most microorganisms like to grow?

A

fairly moderate environmental conditions

61
Q

what environmental conditions do extremophiles like?

A

harsh conditions that would kill most other microorganisms

62
Q

what domain are most extremophiles?

A

mostly prokaryotes; often archaea, but some bacteria

63
Q

define extremophiles

A

organisms with range of metabolic diversity and physiological capacities that allow them to live in extreme environments

64
Q

list the 5 main environmental extremes that extremophiles like

A
  1. temperature
  2. pH
  3. salinity
  4. pressure
  5. oxygen or NO oxygen
65
Q

do all extremophiles need water to live?

A

nope, they’re hard motherfuckers

66
Q

give 3 more examples of hardcore environments where extremophiles can live

A
  1. rocks?? oh my god??
  2. heavy metal tolerance
  3. radiation
67
Q

list a describe the two/three temperature extremophiles

A
  1. psycrophiles: cold-loving
  2. thermophiles: heat-loving, and ever go harder to
  3. hyperthermophiles: super heat-loving
68
Q

list and describe the two pH extremophiles

A
  1. acidophiles: acid-loving

2. alkaliphiles: alkaline-loving

69
Q

describe halophiles

A

salt-loving, salinity guys

70
Q

list and describe the two pressure extremophiles

A
  1. osmophiles: high osmotic pressure-loving

2. piezophiles/barophiles: high atmospheric pressure-loving

71
Q

how do psychrophiles adapt to live in temperatures 15 degrees celsius or less? (3)

A
  1. produce proteins and enzymes that function at low temps
  2. membrane contains more UNsaturated fatty acids
  3. genome is higher in G-C content
72
Q

how do thermophiles adapt to live at temps above 45 degrees celsius? (3)

A
  1. produce proteins and ezymes that are stable at high temps
  2. cytoplasmic membrane has more saturated fatty acids to remain stable
  3. utilize gene transfer
73
Q

how do acidophiles adapt to live a low pH levels? (3)

A
  1. cell membrane impermeable to restruct influx of protons into cytoplasm
  2. reduction or pore size in membrane
  3. specialized mechanisms prevent entry of proton into the cell and acid hydrolysis of membrane, like increased removal or protons and cell buffer molecules
74
Q

how do alkaliphiles adapt to live at high pH levels above 9? (3)

A
  1. utilize mechanisms to acquire H+ from extracellular environment and reduce H+ leakage
  2. ATP synthetis contributes to pH homeostasis, prevents release of protons during the ETC
  3. produce metabolic acid that increases H+ in ctyoplasm
75
Q

how do xerophiles adapt to live in environments with low water availability? (4)

A
  1. dormancy (sporulation)
  2. biofilm formation
  3. increased fatty acid content in cell membrane, reducing membrane permeability
  4. produce proteins that counteract the effects of low water activity
76
Q

how do halophiles adapt to actually require high salt concentrations for their survival and growth? (3)

A
  1. accumulate lagre salt concentrations in their cytoplasm for equilibrium
  2. produce compatible organic molecules
  3. produce proteins and enzymes with substantial number of protein charges and increased hydrophobicity
77
Q

how do osmophiles adapt to survive in environments with high osmost pressures like high sugar concentration? (2)

A
  1. produce different osmoprotectants (alcohols and amino acids) that prevent change in osmotiv pressure inside the cell
  2. proteins and enzymes that havemore protein charges and hydrophobicity that protects against the change in solute composition in the cytoplasm
78
Q

how do piezophiles/barophiles adapt to grow and trhive optimally at pressures greater than atmospheric pressure? (2)

A
  1. high pressure can cause formations of a gel-like membrane which decreases nutrient uptake and processing and reducing membrane fluidity
  2. protein structure/composition provides high flexibility, preventing conformational changes that would inhibit function
79
Q

what are the most common adaptations of extremophiles to live like that? (4)

A
  1. special proteins and enzymes
  2. changes to cell membrane
  3. changes in cytoplasm
  4. opening/closing channels or similar mechanism to acquire or remove substances to balance intracellular environment
80
Q

what is the typical outome of extreme osmotic concentration flux to most microbe?

A

influx of water in or out of cell, causing it to burst or shrink

81
Q

how do osmophiles adapt?

A

trigger channels in membrane to open, allowing solute to leave or increase their internal osmotic concentration

82
Q

what is the typical outcome of extreme pH flux on most microbes?

A

cytoplasmic pH becomes acidic or alkaline = cell death

83
Q

what is the typical outcome of extreme temps on most microbes?

A

microbes can’t regulate internal temp, so loss of enzyme function

84
Q

how to temperature extremophiles adapt

A

stabilize proteins and membrane

85
Q

which gas has the greatest impact on microbial growth?

A

oxygen

86
Q

what are the 3 categories of microbes based on oxygen?

A
  1. microbes that can use and detoxify oxygen
  2. microbes that can neither use nor detoxify it
  3. microbes that can not use oxygen but CAN detoxify it
87
Q

what happens to oxygen as it enters cellular reactions?

A

it is transformed into several toxic products, that SOME bacteria can detoxify

88
Q

describe the 2-step process that most cells have developed enzymes for to scavenge and neutralize oxygen byproducts

A
  1. superoxide ion is converted into hydrogen peroxide by superoxide dismutase
  2. hydrogen peroxide is then converted to harmless water and oxygen by catalase (catalase test in lab)
89
Q

describe aerobes

A

can use gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products

90
Q

wht is a strict aerobe

A

cannot grow without oxygen

91
Q

give give 3 examples of struct anaerobes

A
  1. most fungi
  2. most protozoa
  3. many bacteria such as Bacillus species and Mycobacterium tuberculosis
92
Q

what are facultative anaerobes?

A

do not require oxygen for metabolism but can use it when it’s present

93
Q

give 2 examples of facultative anaerobes

A
  1. many gram-negative bacteria

2. staphylococci

94
Q

what are anaerobes?

A

lack the metabolic enzyme systems for using oxygem in respiration

95
Q

what are obligate anaerobes?

A

also lack the enzymes for processing toxic oxygen and die in its presence

96
Q

describe microbial environments

A
  1. complex, constantly changing
  2. expose a microorganism to overlapping gradients of nutrients and environmental factors
  3. contain both macro- and microorganisms
97
Q

in what state do most microbes often live? what does this mean

A

growth-arrested states; alive but not reproducing until nutrients provided

98
Q

what kind of environment do most microbes live in?

A

oligotrophic, offer little to sustain life

99
Q

what are the 5 responses microbes have evolved to the starvation and environmental stress they often face?

A
  1. morpholigcal changes (endospore)
  2. enter stationary phase of growth curve
  3. can use cellular components as nutrients
  4. numerous genes and proteins to help
  5. viable but not culturable state
100
Q

how do most microbes grow (in terms of surfaces)

A

attached to surfaces (sessile) rather than free floating (planktonic)

101
Q

what are biofilms?

A

complex, slime-enclosed communitied of microbes attached to the same surface

102
Q

where can biofilms be found? (generally then give 3 examples)

A

ubiquitous in nature and water

  1. dog bowls
  2. tooth brushes
  3. pipes
103
Q

what are the 5 steps of biofilm formation?

A
  1. reversable attachment of planktonic cells
  2. first colonizers form goo layer and become irreversably attached
  3. cell growth and division
  4. production of EPS and formation of water channels
  5. attachment of secondary colonizers and dispersion of microbes to new sites
104
Q

what is EPS in biofilms?

A

extracellular polymeric substance

105
Q

what 2 aspects of biofilms protect microbes from harmful substances?

A
  1. EPS

2. change in attached organisms’ physiology

106
Q

how do microbes communicate with each other in bioflms?

A

quorum sensing

107
Q

describe quorum sensing

A

microbes communicate with each other, exchnage byproducts and genetic material!!

108
Q

what is super important and scary about quorum sensin?

A

microbes exchange genetic material with each other, which contributes to survival and resistance

109
Q

describe heterogeneity in biofilms

A

differences in metabolic activity and locations of microbes

110
Q

how does quorum sensing work?

A

microbes produce small proteins that increase in level as microbes replicate and convert a microbe to a competant state

111
Q

what canyou accomplish by targeting quorum sensing?

A

you can prevent biofilm formation and prevent microbes from becoming pathogenic

Veterinary Microbiology (11 decks)

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