EX. 8 Bacterial Growth and Nutrition Flashcards
(99 cards)
1
Q
Physical factors controlling microbial growth
A
Temperature, Oxygen, pH, and Osmotic conditions
2
Q
Laboratory incubator is usually set at +35C to +37C
A
Mesophiles
3
Q
What is required to be incorporated in the culture media ?
A
NaCl
4
Q
Able to grow over wide ranges of water activity or osmotic concentration
A
Osmotolerant
5
Q
Requires high levels of sodium chloride, usually above about 0.2M, to grow
A
Halophile
6
Q
Growth optimum between pH 0 and 5.5
A
Acidophile
7
Q
Growth optimum between pH 5.5 and 8
A
Neutrophile
8
Q
Growth optimum between pH 8 and 11.5
A
Alkalophile
9
Q
Grows well at 0C and has an optimum growth temperature of 15C or lower
A
Psychrophile
10
Q
Can grow at 0-7C; has an optimum growth temperature between 20 and 30C and maximum around 35C
A
Psychrotroph
11
Q
Growth optimum around 20-45C
A
Mesophile
12
Q
Grow at 55C or higher, optimum often between 55 and 65C
A
Thermophile
13
Q
Has an optimum between 80 and about 113C
A
Hyperthermophile
14
Q
Completely dependent on atmospheric O2 for growth
A
Obligate aerobe
15
Q
Grows equally well in presence or absence of O2
A
Aerotolerant anaerobe
16
Q
Does not require O2 for growth, but grows better in its presence
A
Facultative anaerobe
17
Q
Require O2 levels below 2-10% for growth and is damaged by atmospheric O2 levels (20%)
A
Microaerophile
18
Q
Does not tolerate O2 and dies in its presence
A
Obligate anaerobe
19
Q
Growth more rapid at hydrostatic pressures
A
Barophilic
20
Q
Chemical requirements for controlling microbial growth
A
Carbon and energy sources, Carbon Dioxide, Inorganic and Organic ions
21
Q
Requires increased CO2 (5-10%)
A
Capnophiles
22
Q
Essential elements in all living cells
A
Carbon
23
Q
Required for the synthesis of enzymes and other cellular proteins as well as nucleic acids
A
Nitrogen
24
Q
Needed for nucleotides, the nucleic acids RNA and DNA, the energy storage molecule, ATP, and for structural phospholipids of the cell membrane
A
Phosphorus
25
Essential component of some amino acids from disulfide linkages between different parts of polypeptide chains and contribute to the folding of the chains into the correct secondary and tertiary protein structure
Sulfur
26
Trace elements
magnesium, iron, cobalt, phosphate, potassium
27
Sugar loving
Saccharophilic
28
Can only grow in an environment supplemented with a particular growth facto that is not required by wild strain (protoroph)
Auxotroph
29
Molecular arrangement (vitamin)
Cyanocobalamin (B12)
30
One-carbon metabolism
Folic acid
31
Transfer of acyl group
Lipoic acid
32
Precursor of coenzyme A
Pantothenic acid
33
Amino acid metabolism
Pyridoxine (B6)
34
Precursor of NAD and NADP
Niacin (nicotinic acid)
35
Precursor of FAD and FMN
Riboflavin (B2)
36
Substances that promote growth of the organism and are provided by various body fluids and tissues in vivo and form of yeast extract and blood or blood products in vitro
Growth factors
37
increase in bacterial numbers, not an increase in the size of the individual cells
Bacterial Growth
38
Period of Adaptation
Lag Phase
39
When the cell synthesizes new enzymes, cofactors, and essential metabolic intermediates, and the intercellular pools of nutrients are established
Lag Phase
40
Microorganisms are growing and dividing at the maximal rate possible
Logarithmic or exponential phase (Log phase)
41
Usually used in biochemical and physiological studies
Logarithmic or exponential phase (Log phase)
42
Rate of growth is constant
Logarithmic or exponential phase (Log phase)
43
This phase is "balanced growth" where all cellular constituents are manufactured at constant rates relative to each other
Logarithmic or exponential phase (Log phase)
44
The rates of synthesis of cell components vary relative to one another until a new balanced state is reached due to change in nutrient levels or other environmental conditions
Unbalanced growth
45
Where culture is transferred from a nutritionally poor medium to a richer one
Shift-up
46
There is lag while the cells first construct new ribosomes to enhance their capacity for protein synthesis
Shift-up
47
Culture is transferred from a rich medium to a poor one
Shift-down
48
There is a lag in growth because cells need time to make the enzymes required for the biosynthesis of unavailable nutrients
Shift-down
49
Phase where many important secondary metabolites are produces under the limited nutritional conditions
Stationary phase or phase of equilibrium
50
Cells living = Cells dying due to exhaustion of nutrients and the production of toxic metabolic products
Stationary phase or phase of equilibrium
51
Population growth eventually ceases
Stationary phase or phase of equilibrium
52
Attained by bacteria at a population level of around 10^9 cells per ml
Stationary phase or phase of equilibrium
53
- The result of a genetic response triggered in starving, stationary phase cells
- Cells become dormant without changes in morphology
- Once the appropriate conditions are available microbes resume growth
Viable but nonculturable (VBC)
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- Fraction of microbial population is genetically programmed to die after growth ceases
- Some cells die and the nutrients the leak enable the eventual growth of those cells in the population that did not initiate cell death
- Dying cells are thus "altruistic" they sacrifice themselves for the benefit of the large population
Programmed cell death
55
Gradually the rate of the cell division stops completely, some of the cells die, so that the number of viable cells is reduced
Death phase/ Logarithmic decline phase/ phase of decline/ senescence
56
Incubated in a closed culture vessel with a single batch of medium
Batch culture
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No fresh medium is provided during incubation
Batch culture
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Observed in bacteria able to utilize two different carbon sources
Biphasic growth
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System that can maintain a microbial population in exponential growth, growing at a known rate and constant biomass concentration for extended periods
Continuous culture system
60
Constructed so that the rate at which sterile medium is fed into culture vessel is the same as the rate at which the media containing microorganisms is removed
Chemostat
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Possesses and essential nutrient in limiting quantities
Chemostat
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Growth rate is determined by the rate at which new medium is fed into the growth chamber; the final cell density depends on the concentration of the limiting nutrient
Chemostat
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Has a photocell that measures the turbidity (absorbance) of the culture in the growth vessel
Turbidostat
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Flow rate of media through the vessel is automatically regulated to maintain a predetermined turbidty
Turbidostat
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Time required for a cell to divide or population to double
Generation/doubling time
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Generation time for Pseudomonas
14 minutes
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Generation time for Staphylococcus aureus
30 minutes
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Generation time for Mycobacterium tuberculosis
15 - 24 hours
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Generation time for Treponema pallidum
33 hours
70
Useful in determining the amount of time that passes before disease symptoms appear in infected individuals
Generation/doubling time
71
A direct method used to measure volume of bacterial suspension is placed within a defined area on a microscope slide and are counted
Direct microscopic count
72
Advantages to this direct method are:
- easy, inexpensive, quick
- gives information about the size and morphology of microorganisms
Direct microscopic count
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A disadvantage to this direct method is that to determine population size accurately, the microbial population must be relative large because only a small volume of the population is sampled
Direct microscopic count
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Specially designed slides have chambers of known depth with an etched grid on the chamber bottom
Counting chamber
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Counting chambers included in Direct microscopic count
Breed count method, Petroff-Hausser counting chamber, Hemocytometer, and Electronic cell counter
76
Can be used for counting prokaryotes
Petroff-Hausser counting chamber
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Can be used for both prokaryotes and eukaryotes
Hemocytometer
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For larger microorganisms (protists and yeast)
Electronic cell counter (Coulter)
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A direct method used when quantity of bacteria is very small
Filtration/ Membrane filtration technique
80
A direct method where a sample is filtered through a thin membrane filter whose pores are too small to allow bacteria to pass the filter
Filtration/ Membrane filtration technique
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A thin membrane filter used in Filtration/ Membrane filtration technique
Black polycarbonate membrane filter
82
A most frequently used direct method of measuring bacterial population
Plate count/ Viable cell count
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A direct method that assumes each live bacterium grows and divides to produce one colony
Plate count/ Viable cell count
84
An advantage to this direct method are:
- measures the number of viable cells
- simple, sensitive, and widely used in food, water, and soil analysis
Plate count/ Viable cell count
85
Disadvantages to this direct method are:
- low count result if clumps of cells are not broken up
- takes time for visible colonies to form
Plate count/ Viable cell count
86
The hot agar used in ___ may injure or kill sensitive cells
Pour-plate technique
87
___ sometimes give higher counts
Spread-plate technique
88
This technique begins with a sample being pipetted onto surface of agar plate
Spread-plate technique
89
This technique begins with a sample being pipetted into a sterile plate
Pour-plate technique
90
A direct method used when the microorganism cannot grow on solid media
Most probable number (MPN) method
91
This direct method is based on the fact that the greater the number of bacteria in a sample, the more dilution is needed to reduce the density to the point at which no bacteria are left to grow in the tubes in a dilution series
Most probable number (MPN) method
92
An indirect method measured by spectrophotometer (colorimeter)
Turbidity/ Spectophotometry
93
An indirect method where as the bacteria multiply in a liquid medium, the medium becomes turbid, or cloudy with cells
Turbidity/ Spectophotometry
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An indirect method where when the concentration of bacteria reaches about 10^7 cells per ml, the medium appears slightly cloudy or turbid
Turbidity/ Spectophotometry
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An indirect method where they measure the amount of a certain metabolic product
Metabolic Activity
96
An indirect method used where cells growing in liquid medium are collected by centrifugation, washed, dried in an over, and weighed
Dry Weight
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An indirect method used for filamentous organisms
Dry Weight
98
An indirect method that is not time consuming and not very sensitive
Dry Weight
99
This direct method is for counting bacteria in milk
Breed Count Method
