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chapter 6 Flashcards

1
Q

physical requirements for microbial growth

A
  • temperature
  • pH
  • osmotic pressure
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2
Q

chemical requirements for microbial growth

A
  • macronutrients (CHONPS)
  • trace elements
  • oxygen
  • growth factors
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3
Q

what does temperature affect?

A

protein function in a cell (properly folded)

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4
Q

different classes for optimal growth in temperature

A
  • psychrophiles: 0-25 degree celsius (food spoilage)
  • mesophiles (normal): 25-40” (37)
  • thermophiles: 40-80”
  • hyperthermophiles: ober 80”
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5
Q

temperature tolerance vs optimal growth
look at chart in lecture notes

A
  • x: mesophile (sensitive to high temperature)
  • y: mesophile (tolerates high temperature to a point and has widest range of thermotolerance)
  • z: thermophile (requires higher temperature)
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6
Q

are halophilic in a hypertonic or hypotonic environment and why?

A

hypertonic since salt is outside the cell (over 5% salt) and it must adapt to high osmotic pressure

*note: hypertonic=shrinkage, hypotonic=swelling

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7
Q

optimal pH range for most microorganisms, acidophiles, alkaliphiles, and fungi

A
  • 6.5-7.5
  • acid: less than 6
  • alk.: 8-11
  • fungi: 5-6
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8
Q

what causes internal pH to drop (acidic)?

A

weak acid diffuses into cell while partially giving up protons. it also leads to a growth inhibitory effect

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9
Q

what do buffers do?

A

maintain pH

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10
Q

what are the chemical requirements for growth?

A

essential nutrients, macronutrients, micronutrients, and growth factors

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11
Q

define essential nutrients

A

cannot be synthesizes and must be supplied

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12
Q

what are the required macronutrients?

A

CHONPS, K, Mg, Ca
- C: biggest influence on growth. it is an energy source that can be complex (heterotroph) or CO2 (autotroph)
-cations serve as cofactors or signaling molecules

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13
Q

what are the required micronutrients?

A

Co, Cu, Mn, Fe, Mo, Ni, Zn

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14
Q

what are the organic growth factors?

A

vitamins, amino acids, blood, serum

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15
Q

Describe aerotolerance (oxygen tolerance)

A
  • oxygen used by aerobes in cellular respiration to obtain energy (ATP) from the breakdown of nutrients; serves as terminal electron acceptor (used to differentiate between anaerobic and aerobic)
  • enzymes react with O2 to for either reactive superoxide or hydroxyl radicals
    -damages DNA, RNA, proteins
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16
Q

How are microbes that do not use O2 affected by aerotolerance?

A

microbes become susceptible to damage and require protection

17
Q

name and describe the protective enzymes against oxygen radicals

A

1.) superoxide dismutase (SOD): neutralizes the affect of O2 radicals
2.) catalase and peroxidase: neutralize peroxide anions (O2) in H2O2

18
Q

locate the growth zones on the tube

A

i cant put a fucking picture on here bruh. just imagine it i guess

19
Q

more energy (ATP) in anaerobes lead to…?

A

more growth

20
Q

where there are the most enzymes in test tubes represent what?

A

where growth is at optimal oxygen

21
Q

describe the tubes of O2 effect on growth (i cant put a picture so just look at lecture slide)

A
22
Q

describe obligate aerobe and microaerophile

A
  • obligate: (atmospheric) oxygen at 21% (highest)
  • microaerophile: oxygen is 5-10% (less)
23
Q

describe obligate anaerobe and aerotolerant

A
  • both do not use O2 and either ferment or respire anaerobically
  • obligate: O2 is TOXIC because it lacks protective enzymes
  • aerotolerant: O2 is NOT toxic
24
Q

describe facultative anaerobe

A
  • can use or not use O2, can ferment or respire aerobically/anaerobically (process taken depends on what’s available)
  • O2 is NOT toxic
25
Q

growth medium is formed by a combination of what?

A

macro- and micro-nutrients

26
Q

complex vs defined media

A
  • complex (rich): pre-formed, nutrients cells can readily assimilate (proteins, yeast extract, beef extract)
  • defined (minimal): chemical composition is known and cells must synthesize all required molecules (requirement for fastidious (longer list) bacteria)

*prob should look at a pic

27
Q

liquid vs solid culture media

A
  • liquid: growth studies, harvest DNA, protein isolation
  • solid: agar, formation of colonies, need for pure culture
28
Q

selective vs differential media

A
  • selective: add inhibitory agents
  • differential: see metabolic differences between types
29
Q

define generation time of bacterial growth

A
  • length of time for a cell to divide
  • Generation time (or doubling time) = minutes/generation
30
Q

growth formulas (represents population size):

A

N0 x 2n = NT ; n = # of generations; NT = # cells after n generations; N0 = # cells at start

31
Q

list and describe the phases of the bacterial growth curve

A

1.) lag phase: no growth, acclimation, syntehsis, turn on/off genes
- factors affecting it: inoculum age and size, media composition, and physical factors
2.) log phase: most active, fastest growth, cell size increases
-mid: most active and biggest
-late: slow down of growth begins
3.) stationary phase: growth rate=death rate, stress response (nutrient limited) leads to cell size decreasing and conserving energy, endospores start forming
4.) death phase: lack of nutrients and pH changes lead to exponential death

31
Q

describe the fed-batch culture

A

it feeds additional nutrients (glucose) at mid-log phase leading to extra growth

32
Q

biofilm formation occurs in what? what part of the cell has biofilm?

A
  • disease and the environment (ex: catheters)
  • fimbriae/pili
33
Q

describe the stages of biofilm development

A
  • via chemical and environmental signals
  • originally planktonic cells or “swimmers” (motile form)

1.) attachment monolayer
- seeks a favorable environment
2.) microcolonies
- kinda lose its flagellum
3.) expopolysacc. (EPS) production
- sugar covers cells
- synthesis
- “stickers”
4.) mature biofilm
- biofilm towers
- sustained with the flowing nutrients supply
5.) dissolution and dispersal
- flow in and out to feed everyone, and dissolve if not enough food available
- return to motile form and reseek favorable environment

micro (18 decks)

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