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Microbiology > Lecture 9: Microbial Growth and Control (Ch7,8,and 9) > Flashcards

Lecture 9: Microbial Growth and Control (Ch7,8,and 9) Flashcards

1
Q

The reproductive strategies of eukaryotic microbes

A

– Asexual and sexual, haploid and diploid

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2
Q

Reproductive strategies of bacteria and Archaea

A
  • Haploid only, asexual- binary fission, budding, filamentous - All must replicate and segregate the genome prior to division
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3
Q

most bacteria divide by

A

binary fission

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4
Q

what are the two pathways that cycle during binary fission

A
  • DNA replication and partition - Cytokinesis
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5
Q

Reproduction in prokaryotes

A
  • Binary fission - Budding - Conidiospores (actinomycetes) - Fragmentation of filaments
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6
Q

What is generation time

A

(doubling time) is the time it takes for a population to double

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7
Q

A population of microbes that doubles at a constant rate is an example of

A

exponential growth

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8
Q

What are the 4 phases of the growth curve

A
  • Lag phase - Exponential (log) phase - Stationary phase - Death phase
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9
Q

What occurs during the lag phase of the growth curve

A
  • Cell synthesizing new components
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10
Q

What occurs during the exponential phase of the growth curve

A
  • growth and division is constant and maximal - population is most uniform in terms of chemical and physical properties during this phase
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11
Q

What occurs during the stationary phase of the growth curve

A
  • closed system population growth eventually ceases, total number of viable cells remains constant. (active cells stop reproducing or reproductive rate is balanced by death rate)
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12
Q

Generation (doubling) time varies depending on

A

species of microorganism and environmental conditions

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13
Q

The range of generation (doubling) time is from ____ minutes for some bacteria to _______ for some eukaryotic microorganisms

A

10 minutes for some bacteria to several days for some eukaryotic microorganisms

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14
Q

Direct methods for measuring microbial growth

A
  • Plate counts - Filtration - MPN (most probable number) - Direct microscopic count
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15
Q

What are the indirect methods for measuring microbial growth

A
  • Turbidity - Metabolic activity - Dry weight
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16
Q

how to perform viable counting with spread and pour plate techniques

A
  • Spread and pour plate techniques (the difference is one you spread out and the other you add melted nutrient agar and swirl to mix) ( note that in the spread they only grow on the surface and in the pour method they go on and in the medium) (the pour plate method is used with anaerobes because they can grow under the agar) - Diluted sample of bacteria is spread over solid agar surface or mixed with agar and poured into Petri plate - After incubation the number of organisms are determined by counting the number of colonies multiplied by the dilution factor - Results expressed as colony forming units (CFU)
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17
Q

viable counting via the membrane filter technique

A
  • bacteria form aquatic samples are trapped on membranes - membrane soaked in culture media - colonies grow on membrane - colony count determines number of bacteria in sample
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18
Q

If a microbe cannot be cultured on plate media then

A

dilutions are made and added to suitable media (turbidity determined to yield the most probable number (MPN))

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19
Q

bacterial growth can be measured with a _____, which measures the absorbance at 600nm

A

spectrophotome

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20
Q

Do bacteria have limited control over their internal environments

A

Yes. This is why the environmental factors affect microbial growth

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21
Q

Requirements for growth can be divided among ___ and ____ requirements

A

Physical and chemical requirements

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22
Q

What are some physical requirements that regulate bacterial growth

A
  • Temperature - pH - Osmotic pressure
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23
Q

What some of the chemical requirements that regulate bacterial growth

A
  • Carbon - nitrogen, sulfur, phosphorous - Trace elements - Oxygen - Organic growth factor
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24
Q

Examples of osmotolerant microorganisms

A
  • Staphylococcus aureus - Saccharomyces rouxii
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25
Q

Examples of Halophile (requires high levels of sodium chloried, usually above about 0.2M, to grow)

A
  • Halobacterium, Dunaliella, Ectothirohodospira
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26
Q

examples of Acidophile (Growth optimum between pH 0 and 5.5)

A
  • Sulfolobus - Picrophilus - Ferroplasma - Acontium
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27
Q

Temperature range of psychrophiles

A

0- 20 degrees C

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28
Q

temperature range of psychrotrophs

A

0-35 degrees C

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29
Q

Temperature range of mesophiles

A

20-45 degrees C

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30
Q

Temperature range of thermophiles

A

55-85 degrees C

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31
Q

Temperature range of hyperthermophiles

A

85- 113 degrees C

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32
Q

Danger zone for bacterial growth

A
  • 15-50 degrees C - 60-130 degrees F
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33
Q

What are the cardinal temperatures

A

Minimum, maximum, and optimum temperature

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34
Q

Adaptations of thermophiles

A
  • Protein structure stabilized by a variety of means: more H bonds, more proline, and chaperones - Histones- like proteins stabilize DNA - Membrane stabilized by variety of means (more saturated, more branched and higher molecular weight lipids, ether linkages (archaea like membranes)
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35
Q

Most bacteria grow between pH ____ and ____

A

6.5 and 7.5

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36
Q

Molds and yeasts how between pH ___ and ___

A

5 and 6

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37
Q

______ grow in acidic environments

A

Acidophiles

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38
Q

What is the optimum pH for acidophilus

A

pH 0 and pH 5.5

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39
Q

Neutrophils growth is optimum between pH ____ and _____

A

pH- 5.5 and pH 7

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40
Q

Alkaliphiles (alkalophiles) growth optimum is between

A

pH 8.5 and pH 11.5

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41
Q

Toxicity is a measure of ______

A

Osmotic pressure (hypertonic, isotonic, hypotonic)

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42
Q

Hypertonic environments, or an increase in salt or sugar, cause _____

A

Plasmolysis

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43
Q

Halophiles grow optimally at

A

NaCl concentration greater than 0.2 M

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44
Q

Extreme Halophiles require NaCl concentration

A

Greater than 2 M

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45
Q

Chemoheterotrophs use ______ carbon sources

A

Organic

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46
Q

Autotrophs use _____ carbon sources

A

CO2

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47
Q

Osmotolerant

A

Able to grow over wide ranges of water activity or osmotic concentration

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48
Q

Halophile

A

Requires high levels of sodium chloride, usually above about 0.2 M, to grow

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49
Q

Obligate aerobe

A

Completely dependent at atmospheric O2 for growth

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50
Q

Facultative anaerobe

A

Does not require O2 for growth but grows better in its presence

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51
Q

Facultative anaerobe

A

Does not require O2 for growth but grows better in its presence

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52
Q

Aerotolerant anaerobe

A

Grows equally well in presence or absence of O2

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53
Q

Obligate anaerobe

A

Does not tolerate O2 and dies in its presence

54
Q

Microaerophile

A

Requires O2 levels between 2-10% for growth and is damaged by atmospheric O2 levels (20%)

55
Q

Growth more rapid at high hydrostatic pressures

A

Piezophile (basophile)

56
Q

Nitrogen requirements

A
  • nitrogen is in most amino acids and proteins - most bacteria decompose proteins - Some bacteria use NH4+ or NO3- - A few bacteria use N2 in nitrogen fixation
57
Q

Sulfur requirements in bacteria

A
  • in amino acids, thiamine, and biotin - Most bacteria decompose proteins - Some bacteria use SO4^2- or H2S
58
Q

Phosphorus requirements in bacteria

A
  • in DNA, RNA, ATP, and membranes - PO4^3- in a source of phosphorus
59
Q

______ is a measure of the ability of a microorganism to grow in the presence or absence of oxygen

A

Aerotolerance

60
Q

Oxygen easily reduced to ________

A
  • toxic reactive oxygen species (ROS) - Superoxide radical - Hydrogen peroxide - hydroxyl radical
61
Q

Aerobes produce protective enzymes such as ____. ____ , and ____ to neutralize toxic reactive oxygen species (ROS)

A
  • Superoxide dismutase (SOD) - Catalase - Peroxidase
62
Q

what is singlet oxygen: O2-

A

normal molecular oxygen (O2) boosted to a higher-energy state

63
Q

Superoxide free radicals: O2 - is reduced by _____ to H2O2 + O2

A

Superoxide dismutase

64
Q

Peroxide anion can be removed via enzymes

A

Catalase or peroxidase

65
Q

all strict anaerobic microorganisms lack or have very low quantities of

A
  • Superoxide dismutase and catalase
66
Q

Anaerobes must be grown without ____

A

O2 (work station with incubator, gaspak anaerobic system)

67
Q

What are capnophiles

A

organisms that require higher than normal atmospheric levels of CO2

68
Q

Olbligate aerobes contain what enzymes

A
  • SOD (+) - catalase (+)
69
Q

Facultative anaerobes contain what enzymes

A
  • SOD (+) - Catalase (+)
70
Q

Aerotolerant anaerobes contain what enzymes

A
  • SOD (+) - Catalase (-)
71
Q

Strict anaerobe enzymes

A
  • SOD (-) - Catalase (-)
72
Q

Microaerophile enzymes

A
  • SOD (+) - Catalase (+/-) (low levels)
73
Q

Adversely affected by increased pressure, but not as severely as non tolerant organisms

A

Barotolerant

74
Q

Barophilic (peizophilic) organisms

A
  • Require or grow more rapidly in the presence of increased pressure - Change membrane fatty acids to adapt to high pressures
75
Q

Destruction or removal of all viable organisms

A

Sterilization

76
Q

Killing, inhibition, or removal of disease causing (pathogenic) organisms

A

Disinfection

77
Q

What are some disinfectants

A
  • agents, usually chemical, used for disinfection - usually used on inanimate objects
78
Q

Reduction of microbial population to levels deemed safe (based on public health standards)

A

Sanitization

79
Q

Prevention of infection of living tissue by microorganisms

A

Antisepsis

80
Q

Chemical agents that kill or inhibit growth of microorganisms when applied to tissue

A

Antiseptics

81
Q

Use of chemicals to kill or inhibit growth of microorganisms within host tissue

A

Chemotherapy

82
Q

Agents that kill microorganisms or inhibit their growth

A
  • cidal agents kill - static agents inhibit growth
83
Q
  • suffix indicating that agent kills
A

-cide

84
Q

Kills pathogens and many no pathogens but not necessarily endospores

A

Germicide

85
Q

Suffix indicating that agent inhibits growth

A

-static

86
Q

What is decimal reduction time

A

Time to kill 90%

87
Q

What are persisted cells

A
  • Viable but nonculturable (VBNC) condition - once they recover they may regain the ability to reproduce and cause infection
88
Q

The pattern of microbial death

A
  • Microorganisms are not killed instantly - population death usually occurs exponentially
89
Q

Conditions influencing the effectiveness of anti microbial agent activity

A
  • Population size (larger populations take longer to kill than smaller populations) - Population composition (microorganisms differ markedly in their sensitivity to anti microbial agents) - Concentration or intensity of an anti microbial agent (usually higher concentrations kill more rapidly but this relationship is not linear) - Duration of exposure (longer exposure means more organisms killed) - Temperature- higher temperatures usually increase killing - Local environment (pH, viscosity, concentration of organic matter, etc. can profoundly impact effectiveness)(organisms in bio films are less susceptible to many anti microbial agents)
90
Q

Filtration reduces microbial population or sterilizes solutions of _______ by _______. Also used to reduce microbial populations in air

A

Heat-sensitive materials by removing microorganisms

91
Q

Porous membranes with defined pore sizes that remove microorganisms primarily by physical screening

A

Membrane filters

92
Q

Filtering air by use of

A
  • Surgical Masks - Cotton plugs on culture vessels - High- efficiency particulate air (HEPA) filters- used in laminar flow biological safety cabinets
93
Q

Physical control methods

A
  • heat - Radiation
94
Q

Moist heat destroys

A
  • Viruses, fungi, and bacteria - boiling will not destroy spores and does not sterilize - Degrades nucleic acids, denatures proteins, and disrupts membranes
95
Q

Moist heat will not destroy ___ and does not ____

A

Spores and does not sterilize

96
Q

Steam sterilization is carried out above ____ which requires saturated stream under pressure

A

100 degrees C

97
Q

stream sterilization uses _____ and is effective against

A

autoclave, all types of microorganisms (including spores)

98
Q

Pasteurization is controlled heating at temperatures

A

Well below boiling

99
Q

Pasteurization does not ______ but does _____

A

sterilize but does kill pathogens present and slow spoilage by reducing the total load of organisms present

100
Q

Dry Heat Sterilization is ____ effective than moist heat sterilization, requiring ____

A

less, requiring higher temperatures and longer exposure times (items subjected to 160-170 degrees C for 2 to 3 hours)

101
Q

Dry heat sterilization ____ cell constituents and _____ proteins

A

oxidizes, denatures

102
Q

_______ are used to sterilize inoculating loops used in microbiology laboratories

A

Bench top incinerators

103
Q

What UV wavelenth is is mot bactercidal

A

260 (DNA absorbs)

104
Q

UV radiation cause ____ dimers preventing replication and transcription

A

thymine

105
Q

UV limited to surface surface sterilization because

A

it does not penetrate glass, dirt films, water, and other substances

106
Q

Gamma radiation penetrates ____ into objects

A

deep

107
Q

Ionizing radiation (gamma radiation) destrosy ____ but is not always effective against

A

bacterial endospores; viruses

108
Q

Ionizing radiation is used for _____ and pasterization of ____, _____, ____, _____, and ____

A

sterilization, antibiotics, hormones, sutures, plastic disposable supplies, and food

109
Q

What to consider when using a disinfectant

A
  • Concentration of disinfectant
  • organic matter (this can interfere with a disinfectant)
  • pH
  • Time
110
Q

Phenolics

A
  • commonly used as laboratory and hospital disinfectants
  • Act by denaturing proteins and disrupting cell membranes
  • Tuberculocidal, effective in presence of organic material, and long lasting
  • Disagreeable odor and can cause skin irritation
111
Q

Alcohols

A
  • Among the most widely used disinfectants and antiseptics
  • Two most common are ethanol and isopropanol
  • Bactericidal, fungicidal, but not sporicidal
  • Inactive some viruses
  • Denature proteins and possibly dissolve membrane lipids
112
Q

Ethanol and isopropanol require

A

Water

113
Q

Iodine

A
  • Skin antiseptic
  • oxidizes cell constituents and iodinates proteins
  • At high concetrations may kill spores
  • Skin damage, staining, and allergies can be a problem
  • Iodophore
    • Iodine complexed with organic carrier
    • released slowly to minimize skin burns
114
Q

Chlorine

A
  • Oxidizes cell constituents
  • Important in disinfection of water supplies and swimming pools, used in dairy and food industries, effective household disinfectant
  • destroys vegetative bacteria and fungi
  • Chlorine gas is sporicidal
  • Can react with organic matter to form carcinogenic compounds
115
Q

Heavy metals

A
  • Ions of mecury, silver, arsenic, zinc, and copper
  • Effective but usually toxic
  • Combine with and inactivate proteins; may also precipitate proteins
116
Q

Quaternary Ammonium Compounds

A
  • Detergents that have antimicrobial activity and are effective disinfectans (amphipathic organic
  • Cationic detergents are effective disinfectants
    • Kill most bacteria, but not M. tuberculosis or endospores
    • Safe and easy to use, inactivated by hard water and soap
117
Q

Aldehydes

A
  • Commonly used agents are formaldehyde and glutaraldehyde
  • highly reactive molecuels
  • Sporicidal and can be used as chemical sterilants
  • Combine with and inactivate nucleic acids and proteins
118
Q

Phenol Coefficient Test

A
  • Potency of a disinfectant is compared to that of phenol
  • useful for screening but may be misleading
119
Q
A
120
Q

Dilution test

A
121
Q

dilution test

A

determines rate at which selected bacteria are destroyed by various chemical agents

122
Q

Method for evaluating the effectiveness fo disinfectants

A
  • Metal rings dipped in test bacteria are dried
  • Dried cultures are placed in disinfectant for 10 minutes at 20 degrees C
  • Rings are transferred to culture media to determine whether bacteria survived treatment
123
Q

normal in-use testing

A

-testing done using conditions that approximate normal use of disinfectant

124
Q

Streptomycin

A
  • anitbiotic active against tuberculosis
125
Q

General characteristics of antimicrobial drugs

A
  • Selective toxicity
  • Therapeutic dose
  • Toxic dose
  • Therapeutic index
126
Q

Selective toxicity

A

ability of drug to kill or inhibit pathogen while damaging host as little as possible

127
Q

Drug level required for clinical treatment

A

Therapeutic dose

128
Q

Drug level at which drug becomes too toxic for patient (produces side efects)

A

Toxic dose

129
Q

Ratio of toxic dose to therapeutic dose

A

Therapeutic index

130
Q
A
131
Q
A

Microbiology (16 decks)

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