Bacterial Visualization, Growth and Control Flashcards Preview

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Flashcards in Bacterial Visualization, Growth and Control Deck (112)
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61

thermophiles

heat tolerant bacteria

62

E. coli optimum growth

37 C
proteins begin to denature at 40 C+

63

pH

measure of hydrogen ions in solution

64

fungi pH

4.5- 6.0

65

blood pH

7.4 (7.2 and 7.6 are toxic)

66

buffers

prevent abrupt changes in pH
donate or remove Hydrogen ions in solutions
ex phosphate salts, calcium carbonate added to culture

67

oxygen manipulation techniques (3)

thioglycolate
Brewer anaerobic jar
candle jar

68

thioglycolate

establishes oxygen gradient in culture
bottom of tube anaerobic

69

Brewer anaerobic jar

combines oxygen with hydrogen to form water
anaerobic

70

candle jar

burning candle reduces oxygen concentration
microaerophilic

71

strictly aerobic

require atmospheric levels of oxygen
Pseudomonas aeriginosa

72

obligate anaerobic

do not use oxygen
killed by oxygen
Clostridium

73

faculative anaerobic

use oxygen if present but can live without it
E. coli
Staphylococcus aureus

74

aerotolerant anaerobic

do not use oxygen but not harmed by it
Lactobacillus

75

microaerophiles

require oxygen but less than atmospheric
Neisseria sicca
Micrococcus

76

Bacterial growth limiting factors

physical- temperature, pH, osmotic pressure
chemical- all molecules required for growth and reproduction
C, O, N, S, P, trace elements, organic growth factors

77

bacterial growth curve phases

lag, log (exponential), stationary, death (decline)

78

lag phase

onset of colony formation from 1 cell or few cells
length depends on inoculation source, amount of resources available

79

log (exponential) phase

begins with few cells, optimal conditions and abundant resources
exponential growth characterized by rapid doubling time

80

log phase limitations

environment changes as numbers increase
nutrients are depleted, pH changes (more acidic), toxins increase
growth rate declines, levels off

81

stationary phase

population size remains constant
number of cells added equals number of cells dying
cell metabolism shifts from reproduction to survival
lasts indefinitely if minimum resource levels can be maintained

82

carrying capacity

maximum number of individuals environment will support

83

death (decline) phase

resources eventually become limited
existing cells die off at a faster rate than new cells are added

84

targets of control treatments

external cell wall, cell membrane, proteins, nucleic acids (DNA, RNA), ribosomes, enzymes

85

bacterial control methods

disinfection/ sterilization, physical/ chemical

86

disinfection

microbiostatic- does not completely eliminate bacteria
inhibits or prevents growth- low numbers not disease causing
decontamination, antisepsis

87

decontamination

remove bacteria from surfaces

88

antisepsis

disinfection of living tissue

89

sterilization

microbiocidal; kills all microbes including endospores

90

physical controls

heat
refrigeration
radiation
osmotic treatment
filtration