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BIOL 222 > Ch. 6 Microbial Growth > Flashcards

Ch. 6 Microbial Growth Flashcards

1
Q

growth

A

increase in the number of cells

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2
Q

physical requirements for growth

A

1) temp
2) pH
3) osmotic psi

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3
Q

temperature requirements different species

A

different species have different temp ranges. each has a minimum (slow growth) and optimal temp (short range) and maximum (do not grow above it)

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4
Q

psychrophiles

A
  • cold loving
  • optimal temp 12-13 C
  • can grow below freezing
  • can’t grow much above - room temp (18-20C)
  • extreme environments
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5
Q

psychrotrophs

A

room temp optimal. Can grow inside of fridge. tend not to grow below freezing

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6
Q

mesophiles

A
  • middle loving
  • optimal temp approx 37 C
  • can grow as cold as 10 C
  • don’t survive much above 50 C
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7
Q

thermophiles

A
  • heat loving
  • optimal temp above 60 C
  • can’t grow below 40 C
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8
Q

hyperthermophiles/extreme thermophiles

A
  • mostly archaea
  • optimal temp 90-100 C
  • can’t grow below
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9
Q

danger zone of temp

A

12-50 C (rapid range of growth for pathogenic organisms)

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10
Q

neutrophiles optimal pH

A

6.5-7.5

many pathogens and normal microbiota

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11
Q

acidophiles

A

pathogens do not like acidic enviro (hostile)

Lactobacillus

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12
Q

alkalophiles

A

alkaline

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13
Q

molds and yeasts pH

A

5-6

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14
Q

isotonic solution

A

equal osmotic psi in and out of cell

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15
Q

hypertonic solution leads to

A

plasmolysis

plasma membrane shrinks away from cell wall and cell growth is inhibited

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16
Q

hypotonic solution leads to

A

nothing if intact cell wall

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17
Q

halophiles

A

love salt

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18
Q

obligate halophiles

A

require high salt concentrations

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19
Q

facultative halophiles

A

can survive higher salt but don’t have to
Staphylococcus
(2% or even up to 15%)

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20
Q

elements required for growth

A
  • carbon
  • nitrogen
  • sulphur
  • potassium
  • magnesium
  • calcium
  • phosphorus
  • iron
  • trace elements
  • some require organic growth factors (called fastidious)
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21
Q

nitrogen sources

A

NH4+ or NO3- (inorganic ammonium or nitrogen)

N2 (gas, nitrogen fixation)

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22
Q

nitrogen fixing bacteria genuses

A

Rhizobium

Bradyrhizobium

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23
Q

Obligate aerobe

A
  • requires oxygen; aerobic resp only
  • catalase and superoxide dismutase (SOD) allows oxygen free rads to be neutralised
  • Mycobacterium tuberculosis
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24
Q

facultative anaerobes

A
  • both aerobic and anaerobic; greater growth in presence of O2
  • catalase and SOD
  • E. coli and yeasts
25
Q

obligate anaerobes

A
  • only anaerobic growth; growth ceases in O2

- lacks enzymes to neutralize oxygen radicals

26
Q

aerotolerant anaerobes

A
  • SOD allows harmful forms of O2 to be partially neutralized
27
Q

microaerophiles

A
  • only aerobic; O2 in low concentration

- agrobacterium

28
Q

biofilms

A

a collective of one or more types of microorganisms that can grow on many different surfaces

e.g. plaque on teeth

29
Q

how do bacteria communicate to each other to clump together and create biofilms?

A

quorum sensing

30
Q

how do bacteria actually clump together in biofilms?

A

Sticky glycocalyx; has channels so that nutrients etc can pass

31
Q

culture medium

A

any material prepped for growth of bacteria in a lab. Some specialized; must initially be sterile

32
Q

culture

A

microbes growing on the medium (inoculum, solid, or liquid)

33
Q

agar

A

solidifying agent; not broken down by bacteria (not nutrient source)

34
Q

chemically defined media

A

knowing how nutrients affect bacteria (T 6.2 - 6.4)

35
Q

Anaerobic culture techniques

A

contained in bottle or air-lock; reducing media eliminates oxygen. oxyplate lid on a small plate.

36
Q

CO2 incubator

A

can set CO2 %.

37
Q

capnophiles

A

need more CO2 than in normal air.

38
Q

candle jar

A

jar with candle in it. Candle + samples in a jar; CO2 produced from candle in closed jar (for shorter time amount)

39
Q

selective media

A

suppress the growth of unwanted microorganisms

40
Q

differential media

A

everything grows, but distinguishes between species

41
Q

blood agar (sheep blood) and beta hemolysis

A

RBCs destroyed by only certain microorganisms.

S. pyogenes.

42
Q

blood agar and alpha hemolysis

A

S. pneumoniae

43
Q

alpha or beta can indicate whether a sample is:

A

pathogenic. clear spots = pathogens.

44
Q

mannitol salt agar

A

7.5% Na concentration (selective for halophiles)

colour indicates pH; some ferment manitol and some do not (yellow vs red)

45
Q

enrichment medium

A

increase small numbers of bacteria to detectable levels (e.g. soil or fecal samples)

46
Q

two methods of preserving bacterial cultures

A 
deep freezing (-80 degrees)
lyophiliation (dry freeze)
47
Q

Four steps of binary fission (review in textbook!)

A

1) Cell elongates, need more cell wall. Penicillin inhibits this
2) Cell wall and membrane pinch inward
3) Cross wall forms with new DNA
4) May or may not separate

48
Q

mycelium formation (Review in textbook)

A

Conidiospores

Filamentous

49
Q

generation time

A

time it takes a bacterial cell to divide or population to double; different bacteria have different generation time.

50
Q

growth of bacterial cells is…

A

exponential.

51
Q

logarithmic scale

A

growth in straight line

52
Q

phases of growth

A

1) lag phase
2) log phase
3) stationary phase
4) death phase

53
Q

Lag phase

A

bacteria are very metabolically active, but you won’t see a lot of activity. DNA replication and protein synthesis take place, but there is no population increase.

54
Q

Log phase

A

fastest growth

  • still plenty of nutrients and room for growth
  • healthiest cells; transfer cultures at this point (usually ~24 hrs)
  • some cell death, but binary fission far outnumbers it.
55
Q

stationary phase

A

equilibrium of microbial deaths and new cells; running out of space and nutrients.

56
Q

death phase

A

population decreasing at a logarithmic rate; cell death greatly outnumbers binary fission

57
Q

carrying capacity

A

how many cells an environment can support

58
Q

measurement of bacterial growth

A

measure growth in small samples, then multiply to get total number in a culture

e.g. measure 1 mL of a 10 mL sample, count culture amount, multiply by ten.

BIOL 222 (22 decks)

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