Microbial Growth Flashcards

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1
Q

physical requirements that affect growth

A

temperature and pH

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2
Q

chemical requirements that affect growth

A

C, N, S, P, O; trace elements, organic growth factors

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3
Q

psychrophiles

A

0-20C

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4
Q

mesophiles

A

15-45C

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5
Q

thermophiles

A

40-80C

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6
Q

hyperthermophiles

A

65-121

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7
Q

extreme/obligate halophiles

A

require high osmotic pressure

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8
Q

facultative halophiles

A

tolerate high osmotic pressure

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9
Q

obligate aerobe

A

requires oxygen for growth

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10
Q

facultative anaerobe

A

can grow in the presence of oxygen, can grow by fermentation or anaerobic respiration in the absence of oxygen

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11
Q

obligate anaerobe

A

cannot grow in the presence of O

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12
Q

aerobic respiration

A

the final electron acceptor in the ETC is oxygen

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13
Q

culture medium

A

nutrients prepared for microbial growth

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14
Q

sterile

A

no living microbes

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15
Q

inoculum

A

introduction of microbes into medium

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16
Q

culture

A

microbes growing in/on culture medium

17
Q

chemically defined media

A

exact chemical composition is known

18
Q

complex media

A

extracts and digests of meat, yeasts, or plants

19
Q

capnophiles

A

organisms that require high CO2 conditions (similar to intestinal tract)

20
Q

differential media

A

makes it easier to distinguish colonies of different microbes

21
Q

selective media

A

suppress unwanted microbes and encourage desired microbes

22
Q

generation time

A

the time it takes for a population to double in number

23
Q

Mathematical formula to calculate number of microbes (binary fission):

A

Nt = No x 2^n

Where Nt is the final cell number, No is the original cell number, and n is the number of generations

24
Q

generation time of E coli:

A

20-30 minutes

25
Q

batch culture

A

a liquid media within a closed system

26
Q

Exponential growth never lasts __________.

A

indefinitely

27
Q

chemostat

A

ensures logarithmic growth by constantly adding and removing equal amounts of culture media

28
Q

What is similar to a chemostat?

A

human gastrointestinal tract

29
Q

3 Ways to measure microbial growth?

A

Direct count, Viable cell count/plate count, Mass measurements (turbidity)

30
Q

direct count

A

microbes can be counted directly by placing dilutions on a special microscope slide, called a Petroff-Hausser counting chamber

31
Q

Mass measurement (turbidity)

A

light scattering is proportional to cell mass

32
Q

Turbidimetric measurements (4)

A
  1. optical density
  2. light scattering ability of microbial cultures
  3. depends on organism and culture conditions
  4. should be calibrated for the above criteria