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MicroBiology > Microbial Growth Part II > Flashcards

Microbial Growth Part II Flashcards

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Biology 101 flashcards
1
Q

Measurement of Microbial Growth can measure changes in 2 things:

A

number of cells in a population

mass of population

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2
Q

what are the 3 direct cell counts

A

counting chambers
electronic counters – flow cytometry
on membrane filters

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3
Q

describe counting chambers (3)

A

Easy, inexpensive, and quick
Useful for counting both eukaryotes and prokaryotes
Cannot distinguish living from dead cells

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4
Q

describe direct counts on membrane filters (4)

A
  • Cells filtered through special membrane that provides dark background for observing cells
  • Cells are stained with fluorescent dyes
  • Useful for counting bacteria
  • With certain dyes, can distinguish living from dead cells
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5
Q

describe direct counts for flow cytometry (4)

A
  • Microbial suspension forced through small orifice with a laser light beam
  • Movement of microbe through orifice impacts electric current that flows through orifice
  • Instances of disruption of current are counted
  • Specific antibodies can be used to determine size and internal complexity
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6
Q

is whether or not a cell is alive or dead always clear cut in microbiology? describe

A

No it is not always clear cut.

-Cells can exist in a variety of states between ‘fully viable’ and ‘actually dead’

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7
Q

Viable counting methods allows ________ of viable cells

A

enumeration

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8
Q

describe Spread and pour plate techniques in regards to viable counting methods(3)

A
  1. ) diluted sample of bacteria is spread over solid agar surface or mixed with agar and poured into Petri plate
  2. ) after incubation the numbers of organisms are determined by counting the number of colonies multiplied by the dilution factor
  3. ) results expressed as colony forming units (CFU); each CFU comes from 1 viable cell
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9
Q

describe Membrane filter technique in regards to viable counting methods (4)

A

1.) bacteria from aquatic samples are trapped on membranes
2.) membrane soaked in culture media
3.) colonies grow on membrane
4.) colony count determines # of bacteria in sample
(slides 8 and 9 have helpful pictures)

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10
Q

in regards to viable counting methods, if a microbe cannot be cultured on plate media what 2 things can be done?

A
  1. ) dilutions are made and added to suitable liquid media (slide 10)
  2. ) turbidity determined to yield the most probable number (MPN)
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11
Q

describe turbidity/terbidometric measures

A

12-16

Definitely look at and memorize

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12
Q

describe The Continuous Culture of Microorganisms (3)

A
  1. ) Growth in an open system
    - continual provision of nutrients
    - continual removal of wastes and cells
  2. ) Maintains cells in log phase at a constant biomass concentration for extended periods
  3. ) Achieved using a continuous culture system
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13
Q

What are 3 Importances of Continuous Culture Methods?

A
  1. ) Study of microbial growth at very low nutrient concentrations, close to those present in natural environment
  2. ) Study of interactions of microbes under conditions resembling those in aquatic environments
  3. ) Food and industrial microbiology
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14
Q 
The Device for continuous cultures is called what?
describe this (2)
A

Chemostat
-Rate of incoming medium = rate of removal of medium from vessel (with wastes and cells)
-An essential nutrient is in limiting quantities
(picture on slide 19)

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15
Q

Most microorganisms grow in fairly moderate environmental conditions. However, some grow under harsh conditions that would kill most other organisms. What are these organisms called?

A

Extremophiles

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16
Q

slide 21

A

Table

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17
Q

slide 22-23

A

READ THIS
Osmosis stuff
a lot of information

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18
Q

what are Halophiles? (2)

A
  • extremely adapted microbe

- grow optimally in the presence of NaCl or other salts at a concentration in range of grater than 0.2M (2-10 %)

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19
Q

what are extreme halophiles? (4)

A

-extremely adapted microbe
-require salt concentrations of 2M and 6.2M (15- 30 %)
-extremely high concentrations of potassium
-cell wall, proteins, and plasma membrane require high salt to maintain stability and activity
(slide 25)

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20
Q

what is pH? (2)

A
  • measure of the relative acidity of a solution; measure of [H+]
  • negative logarithm of the hydrogen ion concentration
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21
Q

what are acidophiles? (2)

A
  • Microorganisms that growth optimum between pH 0 and pH 5.5

- Mostly prokaryotes; many Archaea

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22
Q

what are neutrophils? (2)

A
  • most microorganisms

- growth optimum between pH 5.5 and pH 7

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23
Q

Alkaliphiles (basophiles)? (2)

A
  • Microorganisms growth optimum between pH 8.5 and pH 11.5

- Mostly prokaryotes

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24
Q
  1. ) Most microorganisms maintain an internal pH near _____ because_______________
  2. ) can do this by:
A
  1. ) neutrality, pH extremes can denature proteins and nucleic acids and kill cells
  2. ) -the plasma membrane is impermeable to protons
    - exchange potassium for protons (H+)
    - buffers
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25
Q

describe acidic tolerance response (2)

A
  • pump protons out of the cell

- some synthesize acid and heat shock proteins that protect proteins

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26
Q

Many microorganisms change the pH of their micro habitat by ________________________

A

producing acidic or basic waste products

27
Q

Microorganisms are ___________ and cannot regulate their internal temperature

A

ambitherms

28
Q

slides 30-32

A

:)

29
Q

Microorganisms can be classified into groups by their growth temperature ____

A

optima

30
Q

describe the Psychrophile growth temperature optima (2)

A
  • low temperature (optimum temperature below 15ºC and max of 20ºC or below) (range=0-20)
  • the most extreme representatives inhabit permanently cold environments
31
Q

describe the Mesophile growth temperature optima (5)

A
  • Midrange temperature (optimum between 15ºC and 45ºC)
  • Warm-blooded animals
  • Terrestrial (soil) and aquatic environments
  • Temperate and tropical latitudes
  • Most microorganisms are mesophiles
32
Q

describe the thermophile growth temperature optima

A

high temperature (optimum above 45ºC) ((range=45-85)

33
Q

describe the hyperthermophile growth temperature optima (2)

A

-Very high temperature (optimum above 85ºC)
-Inhabit hot environments including boiling hot springs and seafloor hydrothermal vents that can have temperatures in excess of 100ºC
(slides 44 and 45)

34
Q

what are Psychrotolerant Mesophiles? (2)

A
  • Organisms that can grow at 0ºC but have optima of 20ºC to 40ºC
  • More widely distributed in nature than psychrophiles
35
Q

describe Psychrophile adaptions

A

slide 41 and 42

36
Q

Above ~__°C only prokaryotic life forms exist; no eukaryotes

A

65

37
Q

describe Thermophile adaptions

A

slide 46

38
Q

__________ is the final electron acceptor in the ______________ used in ________________.

A

Molecular oxygen (O2); electron transport chain; aerobic cellular respiration

39
Q

All organisms that use aerobic cellular respiration as its only (or one of several ) energy yielding metabolism requires __________________

A

molecular oxygen (O2)

40
Q

describe strict aerobes

A
  • usually lives at 20/21% oxygen and will die in the absence of oxygen
  • can only do aerobic cellular respiration
41
Q

describe Microaerophiles (2)

A
  • strict aerobes (will die in absence of oxygen), but can use oxygen only when it is present at levels reduced from that in air
  • live in environments with reduced oxygen content (2-10%)
    (i. e., in bodies of water)
42
Q

what are anaerobes?

A

organisms do not do aerobic cellular respiration, but use some other method of energy metabolism, (thus, they do not require(O2) oxygen and may even be killed by exposure)

43
Q

what are Aerotolerant anaerobes?

A

can tolerate some oxygen and grow in its presence (at some level, but usually not 21 % O2) even though they cannot use it

44
Q

what are strict anaerobes? (2)

A
  • organisms that will die in the presence of any oxygen (live deep in bodies of water and deep in the soil)
  • All strict anaerobic microorganisms lack or have very low quantities of superoxide dismutase and catalase
45
Q

what are Facultative anaerobes (aerobes)? (3)

A
  • organisms that can live in the presence or absence of oxygen
  • they do aerobic cellular respiration when oxygen(O2) is present, and some other energy metabolism when oxygen is absent
  • Nearly all prokaryotes & fungi are in this category
46
Q

slide 51 and 52

A

charts and graphs showing the different types of oxygen using organisms and such; make sure to look at slightly

47
Q

Several toxic forms of oxygen can be formed in the cell. They include: (4)

A 
Singlet oxygen  (O-)
Superoxide anion (O2-)
Hydrogen peroxide (H2O2)
Hydroxyl radical (-OH)
48
Q

Toxic forms of oxygen can damage _____ and ______. They can lead to ______ and cause _______ when they get up above a certain threshold of protection and repair.

A 
proteins
nucleic acids
mutations
cell death
(slide 54)
49
Q

describe how different organisms deal with toxic forms of Oxygen

A

-In all cells living in environments with oxygen, enzymes are present to neutralize most of these toxic oxygen species
-Aerobes and facultative aerobes have the most detoxifying enzymes.
-Microaerophiles and aerotolerant anaerobes have less but have some.
-Strict anaerobes – have no detoxifying enzymes
(slide 56)

50
Q

Anaerobes must be grown without O2. What are the 2 ways in which this can be done?

A

1.) work station with incubator
2.) gaspak anaerobic system
(slides 58-60)

51
Q

Microbes that live on land and water surface live at _ atmosphere (atm)

A

1

*Some Bacteria and Archaea live in deep sea with very high hydrostatic pressures

52
Q

what does Barotolerant mean?

A

adversely affected by increased pressure, but not as severely as nontolerant organisms

53
Q

describe Barophilic (peizophilic) organisms (2)

A
  • require presence of increased pressure to grow

- change membrane fatty acids to adapt to high pressures

54
Q

describe ionizing radiation (4)

A
  • X-rays and gamma rays
  • Can cause mutations at low doses and death at higher doses (sterilization)
  • Disrupts chemical structure of many molecules, including DNA
  • damage may be repaired by DNA repair mechanisms if small dose
55
Q

what is a microorganism that is extremely resistant to DNA damage?

A

Deinococcus radiodurans

56
Q

describe UV radiation damage(5)

A
  • wavelength most effectively absorbed by DNA is 260 nm
  • can cause mutations (low dose) –>death (higher dose)
  • causes formation of thymine dimers in DNA
  • requires direct exposure on microbial surface
  • DNA damage can be repaired by several repair mechanisms
57
Q

describe visible light radiation damage (2)

A

-at high intensities generates singlet oxygen (1O2)
(powerful oxidizing agent)
-carotenoid pigments
(protect many light-exposed microorganisms from photooxidation)

58
Q

Microbial environments are… (3)

A
  • complex
  • constantly changing
  • often contain low nutrient concentrations (oligotrophic environment)
59
Q

microbes that grow attached to surfaces are called what? These attached microbes are members of complex, slime enclosed communities called a _____

A

sessile; biofilm

60
Q

microbes that grow free floating are called what?

A

planktonic

61
Q

Biofilms are _______ in nature in water and can be formed on any ___________

A

ubiquitous; conditioned surface

62
Q

describe biofilm formation (2)

A
  • Microbes reversibly attach to conditioned surface and -release polysaccharides, proteins, and DNA to form the extracellular polymeric substance (EPS)
  • Additional polymers are produced as microbes reproduce and biofilm matures
63
Q

describe biofilms (3)

A

-A mature biofilm is a complex, dynamic community of microorganisms
-Heterogeneity is differences in metabolic activity and locations of microbes
-Interactions occur among the attached organisms
(exchanges take place metabolically, DNA uptake and communication)

64
Q

slide 72

A

Last slide :)

MicroBiology (17 decks)

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