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Microbiology > 3. Microbial Growth and Nutrition > Flashcards

3. Microbial Growth and Nutrition Flashcards

1
Q

Macronutrients

A
  • elements required in large amounts to build macromolecules
  • CHONPS
  • make up more than 90% of the dry weight cell
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2
Q

Types of macromolecules

A

lipids, carbs, proteins and nucleic acid

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3
Q

Proteins

A
  • CHON and sometimes S
  • polymer made of building blocks
  • more than 50% of dry weight
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4
Q

Lipids

A
  • CHO and sometimes P
  • building blocks of fatty acids and glycerol
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5
Q

Carbohydrates

A
  • CHO and sometimes N
  • building blocks of sogars
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6
Q

Nucleic acids

A
  • CHONP
  • building blocks of nucleotides
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7
Q

If the macromolecular composition of a cell has a lipopolysaccaride what kind of gram is it

A

gram negative

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8
Q

Other macronutrients - inorganic ions

A

K, Mg, Ca, Fe

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9
Q

What are inorganic ions used for

A

metabolic cofactors
- used in addition to macronutrients
- its the non-protein component required for enzyme function

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10
Q

K+, Fe2+, Mg2+, Ca2+

A

K+ - enzymes for protein synthesis
Fe2+ - cytochromes to carry
Mg2+ - stabilize membranes and nucleic acids
Ca2+ - stabilize cell walls and heat stability for endospores

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11
Q

How can you remember all macronutrients?

A

C HOPKNS CaFe Mg - the c hopkins cafe is mighty good

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12
Q

Micronutrients

A
  • trace elements required in very small amounts
  • cofactors for enzyme
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13
Q

Growth factors

A
  • small organic molecules required for growthh
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14
Q

What happens if an organism cannot synthesize a growth factor?

A

it must be added to medium to grow that microbe in the lab

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15
Q

Three classes of growth factors

A
  1. Amino acids
  2. Purines and pyrimidines
  3. Vitamins
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16
Q

Amino acids

A

needed for protein synthesis

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17
Q

Purines and pyrimidines

A

AG - 2 rings
TCU - 1 ring

needed for nucleotides, building blocks of RNA and DNA

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18
Q

Vitamins

A
  • small molecules used to make organic cofactors
  • non-protein components required by some enzymes
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19
Q

Growth factor requirements

A
  • many have none (E.coli) some require alot (Leuconostoc mesenteroides)
    -some may require a medium to promote growth
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20
Q

Nutrient sources of O and H

A
  • no specific nutrient
  • Found in H2O and organic media components
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21
Q

Nutrient sources of P

A
  • usually a phosphate salt
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22
Q

Limiting nutrient

A

In relatively low concentration compared to other nutrients
- when it runs out, growth stops despite other nutrients present

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23
Q

Nutrient sources of N

A
  1. inorganic - salt - reduced to NH3 to make amino acids
  2. organic - rich organic molecules - doesn’t need to be reduced
  3. atmospheric N2 - N2 is reduced to NH3 - nitrogen fixation - energy expensive - only bacteria and archaea
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24
Q

Nutrient sources of S

A
  1. inorganic - salt - reduced to S2- to make amino acids - assimilative sulfate reduction
  2. organic - pre-made amino acids - less energy to assimilate
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25
Q

Nutrient sources of C

A
  • Depends on the type of organism
  • If heterotrophs - organic carbon (C and H) - 1 or more C is reduced
  • If autotrophs - inorganic carbon (CO2) as their sole source of carbon - needed energy to assimilate - photosynthesis
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26
Q

Metabolism

A

the sum total of all the chemical rxns in a cell

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27
Q

Catabolic reactions

A

energy releasing metabolism - break down
- fermentation, respiration

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28
Q

anabolic reactions

A

energy-requiring metabolism - build up
- biosynthesis

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29
Q

Microorganisms can be categorized by

A
  1. energy source
  2. electron source
  3. carbon source
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30
Q

energy sources

A

chemo - chemical
photo - light

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31
Q

electron sources

A

organo - organic
litho - inorganic

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32
Q

carbon sources

A

hetero - pre-existing
auto - inorganic

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33
Q

Chemoorganotrophs

A

energy from chemical reactions involving organic material

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34
Q

chemolithotrophs

A

energy from inorganic chemical reactions

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35
Q
A
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36
Q

phototrophs

A

energy from light

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37
Q

heterotrophs vs autotrophs

A

h - use organic carbon for building cell carbon and biomass
a - use co2 to synthesize cell carbons

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38
Q

Basic medium

A

nitrogen fixing photolithoautotroph

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39
Q

medium 1

A

allows Non-nitrogen fixing photolithoautotrophs to grow

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40
Q

medium 2

A

reduced organic carbon source - energy and e- for chemoorganotrophs
- some chemoorganoheterotrophs

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41
Q

medium 3

A

allows growth of chemoorganoheterotrophs with a growth factor requirement

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42
Q

medium 4

A

vitamins! - N source, alternate source of carbon energy and e-

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43
Q

defined medium

A

exact chemical composition is known
- used to study metabolism

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44
Q

minimal medium

A

a type of defined medium that provides the minimum nutritional requirements for growth

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45
Q

complex medium

A

exact chemical composition is not known
- usually made from meat or yeast
- supply a variety of growth factors

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46
Q

differential medium

A

allows different bacteria to be distinguished

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47
Q

Example of differential medium

A

Blood agar - tsoy plate - 5% sheeps blood

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48
Q

Hemolytic bacteria (destroying red blood cell)

A

alpha - incomplete destruction of blood cells
beta - complete destruction
gamma - no destruction (not hemolytic)

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49
Q

Selective medium and example

A

contain ingredients that inhibit the growth of unwanted microbes - allow only specific microbes to grow
- Ex) mannitol salt agar - contains very high salt so only halotolerant bacteria can grow - isolate staphylococci from skin

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50
Q

Enriched medium

A
  • supplemented with special nutrients to encourage the growth of fastidious bacteria
  • complex nutrient requirements
  • Ex) blood agar, chocolate agar
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51
Q

how is growth measured for microbio?

A

increase in the number of cells of apopulation not individual growth
- increase through binary fission - cell division following enlargement of a cell to twice its mini size

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52
Q

generation time (G)

A

time required for microbial cells to double in number

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53
Q

cell division - euk vs pro

A

pro: growth in cell size, chromosome replication and septum formation occur at the same time - no mitosis
euk: growth, replication, seperation are at differnt times
bacteria have shorter generation times than eukaryotes

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54
Q

what is generation time dependent on

A

growth medium and incubation conditions

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55
Q

exponential growth

A

growth of a microbial population in which cell numbers double at a constant and specific time interval

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56
Q

relationship between initial number vs final number

A

Nf = N0x2^n - final cell number is equal to inital cell number multiplied by 2 to the power of number of generations

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57
Q

exponential growth for this one

A

0.5 hour

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58
Q

What is this graph showing?

A

because cells increase exponentially the increase in cell number is initially slow but increases at an ever faster rate following an exponential curve - cells are doubling at a constant rate

59
Q

Why is unlimited growth called exponential growth

A

it generates a curve whose slope increases conitnuously

60
Q

Growth rate (k)

A
  • rate of increase in population number or biomass
61
Q

Why is pro growth rate expressed as the number of doublings per hour

A

they grow by binary fission - always doubling

62
Q

N0 = 0.5 x 107 cells
NF = 1.00 x 107 cells
Dt = 4.2 - 3.5 = 0.7 hour
K? and G?

A

k = (log1x107 - log0.5x107)/(.301)(0.7)
k = 1.43 gen/hr

g=1/k
g= 1/1.43 = 0.7hr/gen

63
Q

specific growth rate

A

for each organism, they have a growth rate that is the fastest in the best growth medium at optimal temperature

64
Q

batch culture

A

a closed-system microbial culture of fixed volume - once inoculated - thats all you get - because theres a fixed number of resources

65
Q

Growth curve for population of cells phases

A
  1. lag phase
  2. exponential phase
  3. stationary phase
  4. death phase
66
Q

lag phase

A

interval between inoculation of a culture and beginning of growth
- adapting to new environment
- ex) when you add bacteria to a tsoy plate
- small increase in cells is due to transition - elongating cells but not division

67
Q

exponential phase

A
  • LOG phase - doubling happens here
  • cells in this phase are typically in the healthiest state
    which is why we use it for calculating growth rate
68
Q

stationary phase

A
  • cells metabollically active but growth rate of population is zero
  • either an essential nutrient is used up or wast product of organism accumulates in medium
69
Q

death phase

A
  • if incubation continues after cells reach stationary phase, cells will eventually die
  • not all bacteria die, some bacteria form spores of cysts or dormant stages that allow a significant proportion of cells to survive a long time
70
Q

continuous culture

A

an open system microbial culture of fixed volume
- new nutrients and wastes are consistent

71
Q

chemostat

A

most common type of continuous culture device
- growth rate and population density of culture can be controlled independently and at the same time
- dilution rate - rate at which fresh medium is pumped in and spent medium is pumped out
- concentration of a limiting nutrient controls the population size and the growth rate

72
Q

microbial counts

A

direct microscopic observations using a counting chamber
- each square corresponds to a calibrated volume
-results can be unreliable

73
Q

limitations of microscopic counts

A
  • cannot distinguish between live and dead cells without special stain
  • small cells can be overlooked
  • precision is difficult
  • needs a specific microscope
  • low density cells are hard to count
  • hard to count motile cells
  • debris can be mistaken for cells
  • cells may move and form clumps
74
Q

flow cytometry

A

automaticlaly counts the total number of cells based on laser beams, dyes and electronics

75
Q

viable cell counts and how?

A
  • measure only living cells - cells that are capable of growingto form a population
  • 2 main ways: spread plate or pour plate
76
Q

issues with viable cell counts

A
  • needs alot of preparation and incubation time for a culture
  • plate counts are unreliable when used to assess total cell numbers of natural samples
  • selective culture media and growth conditions target only particular species - a single medium cant grow every microbe - can only count the types of bacteria that can grow in the medium selected
77
Q

great plate anomaly

A
  • microscopic counts reveal more organisms than plate counts
  • genome techniques suggest that only 1-10% of microbial diversity is culturable from most environment samples because
    1. microscopic methods count dead cells and viable methods dont
    2. differnt organisms may have vastly different requirements for growth
    3. we dont know the specific requirements for all organisms
78
Q

spectrophotometric counts

A

used for turbidity measurements
- optical density measurement
- bacteria are like small particle and absorb and scatter light
- only a portion of the incident light makes it to the photocell
- the larger the number of particles, the greater the absorbance, the lower the light transmission to the photocell
- can’t distinguish dead cells from living cells

79
Q

what does this graph say

A

standard curve: viable cell counts and weight of biomss produced
- optical density has a fixed linear range of measurement
- it only works if the cells are evenly distributed throughout the medium

80
Q

dry weight measurement (total mass of cells)

A

a specific aliquot cells are concentrated, washed to remove media components, concentrated and dried

81
Q

other spectrometric techniques are used for

A

to measure compoenets of the cell, protein, DNA

82
Q

cardinal temps

A

the minimum, optimum and maximum temps at which an organism grows

83
Q

psychrophile

A

low temp is optimum

84
Q

mesophile

A

midrange temp is optimum
- warm blooded animals, trrestrial and aquatic, temperate and tropical latitudes

85
Q

thermophile

A

high temp optimum

86
Q

hyperthermophile

A

very high temp optimum

87
Q

cold loving microorgnaism

A

extremophiles - organisms that grow under very hot or very cold conditions
psychrphiles - organisms with cold temperature optima - inhabit permanently cold environments
psychotolerant - organisms that can grow at 0 but have optimum of higher

88
Q

adaptations that support cold loving microorganisms

A
  • enzyme; function optimally in the cold
  • modified cytoplasmic membranes - high unsaturated fatty acid content
89
Q

heat loving microorganisms

A
  • only prokaryotic life forms exists
    including chemoorganotrophic and chemolithotrophic species - high diversity
  • thermophiles: organisms with growth temperature optima between 45 and 80 - hot springs, compost
    -hypothermophiles: organisms with optima greater than 80 - hot environments like boiling hot springs, seafloor hydrothermal vents
90
Q

adaptations that support heat loving microorganisms

A
  • cytoplasm membrane:
    bacteria - lipids rich in saturated fatty acids
    archaea - lipid monolayer rather than bilayer
  • hyperthermophiles produce enzymes widely used in industrial microbiology - hydrolytic enzymes like proteases, cellulases and lipases
  • enzymes of thermophiles are more stable and have higher activity than mesophilic counterparts
91
Q

what is the dying temp for life?

A

140-150

92
Q

_________ closest descendants of ancient microbes

A

hyperthermophiles - deepest and shortest branches of the phylogenetic tree
- oxidation of H2 is common
- maybe first energy-yielding metabolism

93
Q

pH and microbial growth

A

some organisms grow best at high or low pH
- most organisms grow between 6-8 - neutrophiles
- less than 6 (low ph) - acidophiles
- higher than 9 (high ph) - alkaliphiles

94
Q

bottom line of pH and adaptations

A
  • cytoplasmic membrane maintains its integrity at the growth pH
  • the internal ph must stay relatively close to neutral even though the external ph is highly acidic or basic
95
Q

how do microbial culture media maintain ph

A

buffers!
- some bactera produce acids to decrease ph
some bacteria grow on amino acids to increase ph

96
Q

water activity

A

water avaialbility is expressed in physical terms
- ratio of vp of air in equil w a substance/solution to vp of pure water
- reflects the amount of water thats interacting with ions and polar compounds in solution

97
Q

cytoplasm has a ____ solute concentration than the surroundings

A

higher; water wants to move into the cell creating turgor pressure

98
Q

halophiles

A

grow best at reduced water potential and have a specific requirement for NaCl
- many marine microbes
- high solute concentration

99
Q

extreme halophils:

A

require high levels of nacl for growth
15-20%
- microbes in the dead sea

100
Q

halotolerant

A

can tolerate some reduction in water activity of environment but generally grow best at lower solute concentrations
- staphy aureus

101
Q

osmphiles

A

organisms that grow with high sugar as solute

102
Q

xerophils

A

organisms able to grow in very dry environments

103
Q

specialized and rare organisms

A

honey, jams and jellies, beef jerky and salted cod

104
Q

high osmolarity created with nacl is used to _________

A

select for acid producing microorganisms
- fermentation
- high salt and low ph prevents growth of MOST pathogens in the finished product

105
Q

mechanisms for combatting low water activity in surroundings:

A
  • pumping inorgnic ions from environment into cell
  • synthesizing or concentrating organic solutes
  • compatible solutes: compounds used by cell to counteract low water activity in surrounding environment
106
Q

obligate aerobes

A

require oxygen to live

107
Q

strict anaerobes

A

don’t require oxygen to live and may die from exposure to oxygen

108
Q

facultative aerobes

A

can live with or without oxygen - they use it if its available

109
Q

aerotolerant anaerobes:

A

can tolerate oxygen and grow in its presence even though they cannot use it

110
Q

microaerophiles

A

can use oxygen only when it is present in a small amount

111
Q

how can oxygen tolerance be distinguished?

A

thioglycolate broth

112
Q

name the type in each

A

a) obligate
b) strict
c) facultative
d) microaerophile
e) aerotolerant

113
Q

how to grow anaerobic techniques

A

reducing agents to reduce oxygen
- removal of air and replacement with an inert gas

114
Q

toxic forms of oxygen formed in cell

A
  1. superoxide anion
  2. hydrogen peroxide
  3. hydroxyl radical
115
Q

enzymes that neutralize toxic oxygen and who lacks some/all of these

A

catalase, peroxidase, superoxide dismutase, superoxide reductase
obligate anaerobes

116
Q

sterilization

A

killing of all viable organisms within a growth medium

117
Q

inhbiition

A

effectively limitng microbial growth
- no killing taking place

118
Q

decontamination

A

the treatmeent of an object to make it safe to handle

119
Q

disinfection

A

directly targets the removal of all pathogens
not necessarily all microorganisms

120
Q

heat sterilization

A
  • controlling microbial growth
  • high temperatures denature macromolecules
121
Q

What cells are resistant to sterilization and what would D be for this

A
  • endospores because they have lipids, sugars, nucleic acids that decrease penetration
  • D would be linear
122
Q

What happens to time when temp decreases for sterilization

A

increase in temp decreases D or time

123
Q

pasteurization

A

using precisely controlled heat to reduce the microbial load in heat-sensitive liquids
- this does not kill all organisms - like endospores
-

124
Q

milk and pasteurization and disease

A

can use diff temps
- LTLT - low temp but for a long time - 63 degrees for 30 mins
- HTST - high temp for a short time - 72 degrees for 15 seconds
- both processes kill Coxiella bernetii - the causative agent of Q fever

125
Q

autoclave

A

a sealed device that uses steam under pressure
- allows temp of water to get 100 degrees
- 121 degrees for 15 minutes at 15 pounds per square inch of pressure is typically used
- the point it takes the longest to heat must stay at 121 for 15 minutes

126
Q

what can kill better and faster? dry or moist

A

moist

127
Q

ionizing radiation

A
  • electromagnetic radiation that produces ions and other reactive molecules generates electrons, hydroxyl radicals, hydride radicals
128
Q

sources of radiation and what its used for in the medical and food industry

A
  • cathode ray tubes, xrays, radioactive nuclides
  • approved by who and is used in the usa to decontaminate foods
129
Q

filtration

A
  • avoids the use of heat on sensitive liquids and gases
  • pores of filters are too small for organisms to pass through - only liquids and gases
130
Q

3 membrane filter types

A
  1. syringe - small volume
  2. pump - large - pushing out
  3. vacuum - large - sucking in
131
Q

nucleapore filtration

A

pore size 5 micrometer - bacteria can pass through
pore size 0.2 micrometer - prevents bacteria from passing through

132
Q

antibacterial agents

A
  1. bacteriostatic
  2. bacteriocidal
  3. bacteriolytic
133
Q

bacteriostatic

A
  • prevents cell growth as long as the antimicrobial agent is present
134
Q

bacteriocidal

A

kills the cell but doesn’t lyse them

135
Q

bacteriolytic

A
  • kills and lyses them
136
Q

why is the cell count still high in bacteriocidal

A

because the defining cell count is the cytoplasmic membrane - so if its not lysed its still there

137
Q

MIC

A

minimum inhibitory concentration
- the smallest amount of an agent needed to inhibit growth of a mircoorganism
- because its expensive to use alot and it could also be toxic
- varies with the organism, inoculum, temp and ph
- lowest concentration with no growth
- it may still have living organisms that arent growing (bacteriostatic)

138
Q

MLC

A

minimal lethal concentration
- when plating the broth from MIC and tubes with higher concentrations, do colonies form?
- the one where colonies stop forming is the MLC

139
Q

whats higher, MLC or MIC

A

MLC

140
Q
A
141
Q

disc diffusion assay

A
  • solid media
  • antimicrobial agent is added to filter
  • MIC is reached
  • forms a zone of inhibition
  • area of no growth around disc
142
Q

antimicrobial agents 2 categories

A
  1. products used to control microorganisms in commercial and industrial applications
  2. products desgined to prevent grwoth of human pathogens in animate environments and on external body surfaces
143
Q

ex of products used to control microorganisms in commercial and industrial applications

A

chemicals in foods, air conditioning cooling towers, textile and peper products, fuel tanks

144
Q

ex of products designed to prevent growth of human pathogens in inaminate environments and on external body surfaces

A
  1. sterilants - destroys all microorganisms including endospores
  2. disinfectant; kills microorganisms but not all endospores
  3. sanitizer - reduced the numbers of microorganisms on surfaces
  4. antiseptic - kills or inhibits the growth of microorganisms but non toxic enough to be applied on living tissue like mouthwash

Microbiology (8 decks)

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