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Microbiology > 4. Microbial Growth > Flashcards

4. Microbial Growth Flashcards

1
Q

most bacterial and archaeal cells reproduce by

A

binary fission
divide into 2, one chromosome

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2
Q

reproductive strategies of bacteria and archaea

A

some budding, filamentous

all must replicate and segregate the genome prior to division

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3
Q

increase in cellular constituents that may result in:

A

-increase in cell number
-increase in cell size

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4
Q

growth refers to

A

population growth rather than growth of individual cells

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5
Q

batch culture

A

-inoculate
-start with set amount
-limited time of microbe growth

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6
Q

continuous culture

A

-culture with broth
-always be replenished with fresh nutrients
-no distinct growth curve

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7
Q

batch culture growth curve

A

lag phase
exponential phase
stationary phase
death phase
long term stationary phase

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8
Q

lag phase

A

cells acclimating to the environment

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9
Q

exponential growth

A

steady growth

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10
Q

stationary phase

A

plateau
number of cells dividing = number of cells dying

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11
Q

continuous culture of microorganisms

A

growth in an open system
-continual provision of nutrients
-continual removal of wastes

maintains cells in log phase at a constant biomass concentration for extended periods

achieved using a continuous culture system
-constant supply of cells in exponential phase growing at a known rate
-study of microbial growth at very low nutrient concentrations, close to those present in natural environment
-study of interactions of microbes under conditions resembling those in aquatic environments
-food and industrial microbiology

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12
Q

chemostats and turbidostats:

A

continually grow cells at a steady rate

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13
Q

chemostat

A

rate of incoming medium = rate of removal of medium from vessel

an essential nutrient is in limiting quantities
most stable and effective at lower dilution rates

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14
Q

turbidostat

A

regulates flow rate of media through vessel to maintain predetermined turbidity or cell density
dilution rate varies
contains all nutrients in excess
operates best at high dilution rates

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15
Q

generation (doubling) time

A

-time required for the population to double in size
-varies depending on species of microorganism and environmental conditions
-range from 10 minutes for some bacteria to days for some eukaryotes

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16
Q

mathematics of growth equation

A

x(2^n)

x= # of starting cells
n= # of generations

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17
Q

extremophiles

A

grow under harsh conditions that would kill most other organisms

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18
Q

categories of extremophiles

A
  1. salt/ solute
  2. temperature
  3. pH
  4. oxygen
  5. pressure conditions
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19
Q

in hypotonic solutions, microbes

A

reduce osmotic concentration of cytoplasm

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20
Q

in hypertonic solutions, microbes

A

increase internal solute concentration with compatible solutes to increase their internal osmotic concentration

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21
Q

halophiles

A

grow optimally in the presence of NaCl or other salts at a concentration above about 0.2 M

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22
Q

extreme halophiles

A

-require salt concentrations between 3M and 6.2 M
-extremely high concentrations of potassium
- cell wall, proteins, and plasma membrane require high salt to maintain stability and activity

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23
Q

nonhalophile

A

less than 0.2 M

24
Q

moderate halophile

A

above 0.2 M will grow but reaches threshold at around 2M before it starts to go down

25
Q

halotolerant

A

will not grow but tolerates it before it starts to go down

26
Q

acidophiles

A

growth optimum between pH 0 and 5.5

27
Q

neutrophiles

A

growth optimum between pH 5.5 and 8

28
Q

alkalophiles

A

growth optimum between pH 8 and 11.5

29
Q

pH preference of microorganisms
most bacteria and protists are

A

neutrophiles

30
Q

pH preference of microorganisms
most fungi prefer

A

more acidic surroundings, about pH 4 to 6

photosynthetic protists also seem to favor slight acidity

31
Q

pH preference of microorganisms
many archaea are

A

acidophiles

32
Q

pH preference of microorganisms
alkaliphiles are

A

distributed among all three domains of life

33
Q

temperature

A

microbes cannot regulate their internal temperature
enzymes have optimal temperature at which they function optimally
high temperatures may inhibit enzyme functioning and be lethal
organisms exhibit distinct cardinal growth temperatures
-minimal
-maximal
-optimal

34
Q

psychrophiles

A

-10 to 20 celsius
can still cause disease- slow

35
Q

psychrotrophs

A

0 to 35

RT AROUND 20
listeria (dairy meat/ cheese)

36
Q

mesophiles

A

20 to 45
human pathogens

37
Q

thermophiles

A

45 to 85 celsius

38
Q

hyperthermophiles

A

85 to 113

above boiling would have to apply pressure

140- bonds in biological bonds start to break down, no life above this

39
Q

adaptations of thermophiles

A

protein structure stabilized by a variety of means
-more H bonds
-more proline
-more chapterones

membrane stabilized by variety of means
-more saturated, more branched and higher molecular weight lipids
-ether linkages (archaeal membranes)

40
Q

growth in presence of different oxygen concentrations depends on

A

a microbes metabolic processes
ETC
terminal acceptor used

41
Q

aerobe

A

grows in presence of atmospheric oxygen which is 20%

42
Q

obligate aerobe

A

requires O2
-O2 is an electron acceptor

43
Q

anaerobe

A

grows in the absence of O2

*anything but O2 can act as an electron acceptor
*aerobic respiration

44
Q

obligate anaerobe

A

usually killed in presence of O2

45
Q

microaerophile

A

requires 2 to 10% O2

little love air

46
Q

facultative aerobes

A

do not require O2 but grow better in its presence

*O2 has most potential to grow ATP
*can respire/ ferment aero/ anaero

47
Q

aerotolerant anaerobes

A

grow with or without O2

*ferments
*grows evenly throughout

48
Q

aerobes produce protective enzymes. for example, catalase

A

breaks down hydrogen peroxide into O2 and H2O

49
Q

barotolerant

A

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

50
Q

barophilic (peizophilic) organisms

A

require or grow more rapidly in the presence of increased pressure
change membrane fatty acids to adapt to high pressures

51
Q

most microbes grow …

A

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

52
Q

biofilm

A

attached microbes are members of complex, slime enclosed communities called a

ubiquitous in nature in water
can be formed on any conditioned surface

53
Q

biofilm formation

A

microbes reversibly attach to conditioned surface and release polysaccharides, proteins, and DNA to form the extracellular polymeric substance (EPS) –> very sticky

cell to cell signaling starts EXOPOLYMER PRODUCTION

additional polymers are produced as microbes reproduce and biofilm matures

54
Q

heterogeneity in biofilms

A

differences in metabolic activity and locations of microbes

fast growers (may be impermeable to disinfectants, antibiotics, antimicrobials) vs slow growers

55
Q

the EPS and change in attached organisms’ physiology

A

protect microbes from harmful agents

when formed on medical devices, such as implants, illness can result

organism sloughing can contaminate water phase above biofilm such as in a drinking water system

56
Q

bacterial cells in biofilms communicate in a density-dependent manner called

A

quorum sensing

57
Q

quorum sensing

A

-produce small proteins that increase in level as microbes replicate and convert a microbe to a competent state
-DNA uptake occurs, bacteriocins are released

Microbiology (8 decks)

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