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BIOL 240 Microbiology > Topic 6 - Culture and Control > Flashcards

Topic 6 - Culture and Control Flashcards

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Biology 101 flashcards
1
Q

metabolism - catabolism =?

A

releases energy

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2
Q

metabolism - anabolism =?

A

consumes energy

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3
Q

catabolism and anabolism

A

CATABOLISM
from: chemicals, light (energy source)
towards:
- energy for biosynthesis
- energy for motility, transport of nutrients, etc
- waste products

ANABOLISM
from: nutrients for biosynthesis
towards:
(biosynthesis) -> macromolecules and other cell components

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4
Q

nutritional requirements!

A

macronutrients
- required by ALL cells to build macromolecules always
- C, N, P, S, O

micronutrients
- required by some cells (like for enzyme parts)
- incl. Fe, Cu, Na, Mg, Mn, etc

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5
Q

metabolism naming steps/parts (3)

A
  1. energy source
  2. electrons
  3. carbon source

1) photo/chemo
2) litho/organo
3) hetero/auto
troph

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6
Q
  1. energy source
A
  • for oxidation, providing electrons for ETC

PHOTO (light energy, photosynthetic: organic or inorganic e-)
or
CHEMO (chemical energy: organic or inorganic e-)

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7
Q
  1. electrons
A

ORGANO (organic) (e.g., glucose, acetate, things with C)
or
LITHO (inorganic) (e.g., H2, NH3, H2O)

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8
Q
  1. carbon source
A
  • for cell maintenance and division

HETEROTROPH (fixed, organic, C-C bonds)
or
AUTOTROPH (gaseous, inorganic, CO2)

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9
Q

nutrition: humans are?

A

chemoorganoheterotrophs

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10
Q

nutrition: cyanobacteria are?

A

photolithoautotroph

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11
Q

energy sources (chemoorganotrophs, chemolithotrophs, phototrophs)

A

chemoorganotrophs
- energy and electrons from oxidation of organic compounds
- i.e. glucose + O2 -> CO2 + H2O

chemolithotrophs
- energy and electrons from oxidation of inorganic compounds
- found only in prokaryotes
- i.e. H2 + O2 -> H2O

phototrophs
- energy from light captured by pigments
- may be oxygenic or anoxygenic (don’t make oxygen, e.g., oxidize Fe)

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12
Q

carbon sources (autotrophs/heterotrophs)

A

carbon needed for energy storage/manipulation, structure

autotrophs
- not all phototrophs! chemoautotrophs exist
- “primary producers”
- fix C directly from CO2

heterotrophs
- use organic molecules produced by autotrophs

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13
Q

acquisition of N: assimilation of ammonia into ____ is most common? with what enzyme?

A

assimilation of ammonia into glutamate/glutamine is most common!

glutamine synthetase

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14
Q

what is N needed for?

A
  • AAs
  • nucleic acids
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15
Q

key nutrient available in ___ amount will limit growth

A

lowest

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16
Q

obligate aerobes

A

require O2

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17
Q

microaerophiles

A

grow best in low lvl of O2

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18
Q

aerotolerant anaerobes

A

not harmed by O2 but don’t use it

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19
Q

obligate anaerobes

A

can’t grow when O2 is present

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20
Q

facultative anaerobes

A

can grow in absence of O2, grows better with O2

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21
Q

why are obligate anaerobes affected by O2?

A

its defenses!
- oxidizing agents: oxidizes things, is toxic
- some lipids can be repaired but some electrons are permanently taken

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22
Q

catalase test

A
  • some microorganisms produce catalase
  • pos test = bubbles
  • neg test = nothing
  • H2O2 + H2O2 -> 2H2O + O2
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23
Q

effects of pH

A
  • affects macromolecule structures and transmembrane electrochemical gradients
  • each microbe has optimal pH range
  • regardless of pH preference, INTRACELLULAR pH stays ~NEUTRAL (some lil low/high in pH extremes)
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24
Q

acidophiles =?

A

love acid, low pH

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25
Q

neutrophiles =?

A

neutral pH

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26
Q

alkalophiles

A

love alkaline, high pH

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27
Q

water activity

A

aw
- interactions with solutes can decrease aw values
- pure water (1.0) has higher aw than seawater
- most bacteria need aw > 0.9

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28
Q

water activity formula

A

aw = vp of air in equilibrium with substance or solution / vp of air with pure water

  • vp of air with pure water would be 100%, max value
  • measure of available water
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29
Q

gram-positive bacteria are bit better at ____ aw survival

A

lower

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30
Q

fungi tend to be ____ (dry, low aw)

A

xerophiles

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31
Q

cytoplasm typically a ___ solute conc than the external env

A

higher!
water tends to move into cell
positive water balance

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32
Q

water loss prevented by ____ internal solute conc
+ how (2)?

A

increasing
- pumping in inorganic ions from env
- synthesis/concentration of organic solutes

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33
Q

what can temp affect? (3)

A
  • macromolecular structure, membrane fluidity, enzyme func
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34
Q

why are eukaryotes limited to mostly being mesophiles or psychrophiles?

A
  • eukarya have mitochondria which aren’t thermophiles, so limited to med/low temp range
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35
Q

thermophile / mesophile / psychrophile, how is it determined?

A

thermophile - hot
mesophile - med
psychrophile - cold

determined through optimal temp

36
Q

effects on cell over optimal temp curve

A

min - membrane gelling; transport processes so SLOW that growth cannot occur

middle - enzymatic rxn occurring faster at higher temp

optimum - enzymatic rxn occurring at max rate

STEEP drop into max - protein denaturation; collapse of cytoplasmic membrane; thermal lysis

37
Q

psychrophiles temp range

A

min <0 deg C
optimum <15 deg C
max ~20 deg C
ex. ocean water

  • often v sensitive to moderate temp (enzymes denature)
  • higher proportion of unsaturated fatty acids in membrane phospholipids than mesophiles
    (kinks discourage gelling in membrane)
38
Q

Psychrotolerant temp range (how are they diff from psychrophiles?)

A
  • can grow ~0-4 deg C
  • optimum 20-40 deg C (why they are diff from psychrophiles)
  • mesophiles capable of low-temp growth
  • found in temperate climates, many soil microorganisms
39
Q

hyperthermophiles

A
  • ex. supervolcano
  • ~50-100 deg C, some go up to 350
40
Q

features that provide thermal stability

A
  • critical AA substitutions in key locations produce heat-tolerant folds
  • increases in ionic bonds between acidic and basic residues: resists unfolding in aqueous cytoplasm
  • certain solutes help stabilize proteins (Di-inositol phosphate, diglycerol phosphate)
41
Q

heat-related modifications in cytoplasmic membrane

A
  • saturated fatty acids in bacteria (decrease fluidity) when hot
  • phospholipid monolayer in archaea more thermotolerant than bilayers
42
Q

agar media

A
  • polysaccharide derived from algae
  • gel at certain temp
  • not degraded by most microbes
  • solidifying agent in micro media
43
Q

what components immediately makes a medium complex?

A

yeast extract
peptone/tryptone

44
Q

media types (2)

A

complex media
defined media

45
Q

specialized media (selective/differential/enriched)

A

selective
- allows for isolation of microbes w/ specific properties

differential
- allows certain microbes to be recognized based on visual reactions in medium

enriched
- used to increase a population of microbes with a specific property

46
Q

Selective AND differential media (3)

A

might be FYI

brilliant green
eosin methylene blue (EMB)

MacConkey

47
Q

3 methods for separating cells on a plate (for isolated colony)

A
  • streak plate method
  • spread plate method
  • pour plate method
48
Q

spread plate vs pour plate

A
  • spread plate uses less bacterial suspension and its on top
  • pour plate uses more bacterial suspension and has colonies inside and on top of the agar
49
Q

3 ways of quantifying microbe

A

direct counts
viable cell counts
turbidity measurements

50
Q

direct count

A
  • known volume is loaded onto slide with a grid
  • cells counted under light microscope
  • cheap, fast, easy
  • can’t differentiate between dead/viable cells
51
Q

viable cell count

A

serial dilutions and CFUs
- culture diluted in a series of tubes then plated
- after incubation colonies are counted

52
Q

CFUs

A

colony-forming units
- CFUs per mL of initial culture calc through multiplying CFUs by inverse of dilution factor
- 25-250 units on a plate for counting is good

53
Q

what if cells are too diluted?

A
  • a filter apparatus can concentrate the cells
54
Q

turbidity

A

spectrophotometer sends light through a culture
- light absorbance can give rough measure of cell density in tube

55
Q

microbial growth curve (what scale? measured with? 4 stages?)

A
  • measured w spectrophotometer
  • logarithmic scale

4 basic phases
- lag phase (microbes preparing for steady growth)
- exponential phase (replicating at a constant and steady exponential rate)
- stationary phase (replication has halted increasing or it’s equal to death rate)
- death phase (nutrients depleted, waste levels high, cells dying at steady exponential rate)

56
Q

what is generation time?

A

time to double the population in exponential phase

57
Q

what is growth rate?

A

number of generations/unit of time (inverse of generation time)

58
Q

what is growth yield?

A

maximum population density and/or amount of cellular material produced by culture

59
Q

controls of microbial growth (4)

A

filtration
temp
radiation
chemical control

60
Q

typical filters (2) & size

A

nylon/teflon filters with pore size of 0.2 or 0.45 um

61
Q

How can viruses be filtered out? what’s the filter size? what does it require?

A

ultrafiltration
- reducing pore size10-100 nm
- requires high pressure

62
Q

0.2 um pore size common; removes particles from ___ and ___

ideal for?

A

liquids and gasses!

ideal when material is heat- or radiation-sensitive

63
Q

3 types of filters

A
  1. depth filter
  2. conventional membrane filter
  3. nucleopore filter
64
Q

depth filter

A
  • fibrous sheet or mat
    – randomly overlapping fibers of diff substances (e.g., paper, glass, like filter paper)
  • used as a pre-filter
  • BIG pore size, NOT for sterilization
    “trapping action”
65
Q

conventional membrane filter

A
  • used for ROUTINE STERILIZATION
  • polymer filter (0.45 or 0.22 um)
    – cellulose acetate or cellulose nitrate
  • pore diameter variable
    “sieve-like action)
66
Q

nucleopore filters

A
  • not default for sterilization
  • for capturing cells for IMAGING
  • thin polycarbonate film (~10 um thick)
    – made w radiation, cracks enlarged by chemical “etching”
    – consistent pore size
  • used for microscopy (filtered material on a single surface plant (1 depth))
67
Q

what is used filter small volumes vs big volumes

A

small vol. = syringe filters
big vol. = peristaltic pump

68
Q

___ heat is more efficient than ____ heat

A

moist (e.g., steam)
dry

69
Q

how does heat sterilize things? how about autoclave? potential problems?

A
  • denatures proteins and nucleic acids
  • 100 deg C kills most microbes quickly
  • an autoclave adds pressure, keeping fluids from evaporating during high temp

problems: hyperthermophiles, endospores, some material can’t be heated

70
Q

autoclave (conditions, efficiency affected by)

A
  • steam under pressure (pressure cooker)
  • 121 deg C, 15 psi above atm
  • efficiency determined by:
    – destruction of endospores
    – vegetative cells
71
Q

T/F pressure helps to kill microbes along with heat in an autoclave

A

False! Just heat

72
Q

how long is sterilization time? does it change?

A

always 15 mins

73
Q

what would happen if an autoclave’s pressure was relieved too quickly?

A

liquids will boil

74
Q

3 stages of autoclave cycle

A
  1. autoclave time
  2. sterilization
  3. exhaust
75
Q

T/F pasteurization sterilizes things

A

False, only reduces microbial load!

76
Q

Pasteurization (purpose, 3 processes)

A

reduces microbial load
- destroys pathogens; 90-99% other microbes killed
- increases shelf life but does not sterilize

common process: high-temp short time (HTST)
- 72 deg C for 15sec

other processes:
- UHT (ultra high temp): 135 deg C for <1 sec
- ESL (extended shelf life): filtration, then lower temp treatment

77
Q

what’s the purpose of low heat and freezing in pasteurization?

A

lower heat - reduces microbe numbers

freezing - can damage cells by forming ice crystals, can stop biochemical rxn
- good for long-term preservation

78
Q

electromagnetic radiation

A

for “sanitization” not really sterilization
- UV radiation of 260-280 nm wavelengths
- can dmg DNA by forming thymine dimers (can kill cell)
- exploited to control microbial growth on non-living surfaces and in water

79
Q

ionizing radiation

A

sterilization! dependent on dose
- protein dmg
- DNA dmg
– double strand breaks
– stray e-
– hydroxide ions
– hydride radicals
- higher energy (measured in Grays Gy), better penetration
- limited to large industrial operations
(ex. medical supplies, grafting tissue)

80
Q

chemicals (Antiseptics, disinfectants, antibiotics)

A

antimicrobial action
- agents target diff groups
– microbicidal, bacteriocidal, fungicidal, algicidal, viricidal
- agents vary wrt selective toxicity
– non-selective
– selective

selective agents useful for treating disease
non-selective agents are NOT for internal use

81
Q

definitions: bacteriostatic/bacteriocidal/bacteriolytic

A

bacteriostatic - growth inhibitory (same viable cell count, same total cell count)

bacteriocidal - kills cells (no viable cell count, same total cell count)

bacteriolytic - causes cell lysis (no viable cell count, no total cell count)

*can be conc-dependent, not just on chemical identity

82
Q

disinfectants vs antiseptics

A

disinfectants: used on NON-LIVING surfaces to kill potentially infectious microbes

antiseptics: used on LIVING tissue to kill potentially infectious microbes (topical only usu)

83
Q

what makes a chemical a good microbe killer?

A
  • kills wide range of microbes
  • not corrosive or too toxic
  • doesn’t leave residue or emit fumes
  • cheap
  • temp stable
84
Q

what are antibiotics?

A
  • antimicrobial agents produced by microbes
  • cidal, static, or lytic (conc-dependent)
  • most work by binding to proteins or cellular organelles and disrupt essential functions necessary for growth and survival of microorganisms
85
Q

details about tetracycline, polymyxin B, penicillin!

A

broad spectrum: tetracycline
narrow spectrum: polymyxin B, penicillin

  • pencillin: inhibit cell wall synthesis (gram pos)
  • tetracycline: disrupt protein synthesis
  • polymyxin b: disrupt cell outer membrane (gram neg)
86
Q

how measure effectiveness of killing targe organism

A

decimal reduction time (D value)
- time require to kill 90% of target organism
(reducing pop size by a decimal)

BIOL 240 Microbiology (10 decks)

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