microbiology ch 6 Flashcards
1
Q
What are three physical factors for microbial growth?
A
Temperature, pH, osmotic pressure
2
Q
What are 7 chemical factors for microbial growth?
A
Carbon, nitrogen, sulfur, phosphorus, oxygen, trace elements and organic growth factors
3
Q
Temperature, pH, and osmotic pressure are physical factors for this
A
Microbial growth
4
Q
Elements like nitrogen, sulfur, phosphorus, oxygen, and carbon, as well as trace elements and organic growth factors, are chemical requirements for this
A
Microbial growth
5
Q
What is the minimum growth temperature?
A
The lowest temperature at which a species will grow
6
Q
What is the optimum growth temperature?
A
The temperature at which a species grows best
7
Q
What is the maximum growth temperature?
A
The highest temperature at which growth is possible
8
Q
What is the typical range of degrees between minimum and maximum growth temperatures?
A
30 degrees celsius
9
Q
This is the lowest temperature at which a species will grow
A
Minimum growth temperature
10
Q
This is the temperature at which a species grows best
A
Optimum growth temperature
11
Q
This is the highest temperature at which a species will be able to grow
A
Maximum growth temperature
12
Q
What temperatures do psychrophiles live in?
A
Cold temperatures
13
Q
What temperatures do mesophiles live in?
A
Moderate temperatures
14
Q
What temperatures do thermophiles live in?
A
High temperatures
15
Q
These microbes grow in cold temperatures
A
Psychrophiles
16
Q
These microbes flourish in moderate temperatures
A
Mesophiles
17
Q
These microbes thrive in high temperatures
A
Thermophiles
18
Q
What temperature range do psychotrophs grow in?
A
Between 0 and 20/30 degrees Celsius
19
Q
These bacteria cause food spoilage
A
Psychrotrophs
20
Q
These bacteria grow between 0 and 20/30 degrees Celsius
A
Psychrotrophs
21
Q
What temperature range do mesophiles grow optimally in?
A
25 to 40 degrees Celsius
22
Q
What temperature type of microbe are the most common?
A
Mesophiles
23
Q
What is the optimal temperature for most pathogenic bacteria?
A
37 degrees C
24
Q
This group of microbes contains the most common spoilage and disease organisms
A
Mesophiles
25
These microbes grow optimally in temperatures of 25 to 40 degrees Celsius
Mesophiles
26
Are mesophiles the most common type of microbe?
Yes
27
Are psychrophiles the most common type of microbe?
No
28
37 degrees is the optimal temperature for this kind of bacteria
Pathogenic bacteria
29
What is the optimum growth temperature range for thermophiles?
50 to 60 degrees C
30
What are two common locations to find thermophiles?
Hot springs and organic compost
31
What is the optimum growth temperature range for hyperthermophiles?
> 80 degrees C
32
What is another name for hyperthermophiles?
Extreme thermophiles
33
Where are two common locations to find hyperthermophiles?
Volcanic hot springs and deep-sea hydrothermal vents
34
These microbes optimally grow between 50 and 60 degrees Celsius
Thermophiles
35
These microbes can be found in hot springs and organic compost
Thermophiles
36
These microbes grow at temperatures above 80 degrees Celsius
Hyperthermophiles
37
These microbes are also called extreme thermophiles
Hyperthermophiles
38
These microbes are found in volcanic hot springs and deep-sea hydrothermal vents
Hyperthermophiles
39
Are hyperthermophiles members of Domain Bacteria?
No
40
What domain do hyperthermophiles belong to?
Archaea
41
What is the optimum pH range for most bacteria?
6.5 to 7.5
42
What is the optimum pH range for molds and yeasts?
5 to 6
43
What type of microbes grow in acidic environments?
Acidophiles
44
What type of microbes grow in basic environments?
Alkaliphiles
45
6.5 to 7.5 is the optimum pH range for these
Most bacteria
46
5 to 6 is the optimum pH range for these two types of microorganisms
Molds and yeasts
47
Acidophiles prefer this type of environment
Acidic environments
48
Alkaliphiles grow in this type of environment
Basic environments
49
Do microorganisms obtain their nutrients in solution from surrounding water?
Yes
50
Do microorganisms require water for growth?
Yes
51
What do extreme/obligate halophiles require for growth?
High osmotic pressure (high salt)
52
Do facultative halophiles require high salt levels?
No
53
Where do microorganisms obtain their nutrients in solution from?
Surrounding water
54
What do microorganisms require for growth?
Water
55
This type of microbe requires high osmotic pressure from high salt concentrations
Extreme/obligate halophiles
56
This type of microbe does not require high salt levels but can tolerate them
Facultative halophiles
57
What can hypertonic environments cause due to high osmotic pressure?
Plasmolysis
58
What is a hypertonic environment?
Concentration of solute is higher outside the cell
59
What type of cell environment can cause plasmolysis?
Hypertonic environment
60
This is an environment in which the concentration of solute outside the cell is higher than inside the cell
Hypertonic environment
61
This element forms the structural backbone of organic molecules
Carbon
62
What do chemoheterotrophs use as energy?
Organic molecules
63
From where do autotrophs derive their carbon?
Carbon dioxide
64
Do chemoheterotrophs use carbon dioxide as a carbon source?
No
65
These derive their carbon from organic molecules
Chemoheterotrophs
66
These derive their carbon from carbon dioxide
Autotrophs
67
This element is essential for the synthesis of proteins, DNA and ATP
Nitrogen
68
What do most bacteria do to get nitrogen?
Decompose protein material
69
What do some bacteria use as a nitrogen source?
NH4+ or NO3- from organic material
70
What do a few bacteria use in nitrogen fixation?
N2
71
What three things is nitrogen essential for?
Synthesis of proteins, DNA, and ATP
72
Why do most bacteria decompose protein material?
For a nitrogen source
73
Do most bacteria use NH4+/NO3- from organic material as a nitrogen source?
No
74
Do a few types of bacteria use N2 in nitrogen fixation?
Yes
75
What is sulfur used for?
Synthesis of amino acids that contain sulfur, and in vitamins such as thiamine and biotin
76
What do most bacteria do for their sulfur source?
Decompose protein
77
What do some bacteria use for a sulfur source?
SO4 2- or H2S
78
What three molecules is phosphorus used to make?
DNA, RNA, ATP
79
Is phosphorus used for the synthesis in phospholipids of cell membranes?
Yes
80
This ion is a source of phosphorus
PO4 3-
81
Certain amino acids as well as vitamins such as thiamine and biotin use this element in their synthesis
Sulfur
82
Do few bacteria decompose protein for their sulfur source?
No
83
Do most bacteria use SO4 2- for their sulfur source?
No
84
This element is used in DNA, RNA, and ATP
Phosphorus
85
This element is used for the synthesis in phospholipids of cell membranes
Phosphorus
86
What are trace elements?
Inorganic elements required in small amounts
87
What are trace elements typically required for?
Enzyme cofactors
88
What are four examples of trace elements?
Iron, copper, molybdenum, and zinc
89
These are inorganic elements required in small amounts
Trace elements
90
These are typically required as enzyme cofactors
Trace elements
91
These include iron, copper, molybdenum, and zinc
Trace elements
92
What do aerobes required for growth?
Oxygen
93
What do microaerophiles require?
Oxygen concentration lower than air
94
What microbes are unable to use oxygen and are often harmed by it?
Anaerobes
95
What are aerotolerant anaerobes?
Microbes that can tolerate but not use oxygen
96
Are obligate anaerobes killed by oxygen?
Yes
97
Do obligate aerobes not require oxygen?
No
98
These grow in the presence of air or require oxygen for growth
Aerobes
99
These microbes require oxygen
Obligate aerobes
100
These microbes grow via fermentation or anaerobic respiration when oxygen is not available
Facultative anaerobes/aerobes
101
These require oxygen concentration lower than air
Microaerophiles
102
These can tolerate but not use oxygen
Aerotolerant anaerobes
103
These are killed by oxygen
Obligate anaerobes
104
What is singlet oxygen?
O2-, a normal molecular oxygen boosted to a higher energy state
105
Is singlet oxygen reactive?
Yes
106
What are four toxic forms of oxygen?
Singlet oxygen (O2-), superoxide radicals (O2-), peroxide anion (O2 2-), and hydroxyl radical (OH*)
107
What enzyme changes O2- to O2?
Superoxide dismutase
108
This is a normal molecular oxygen boosted to a higher energy state and is extremely reactive
Singlet oxygen
109
What is superoxide dismutase?
Enzyme that facilitates reaction of O2- to O2
110
What enzyme changes peroxide anions into less toxic forms?
Peroxidase
111
What are organic growth factors?
Essential organic compounds an organism is unable to synthesize
112
From where must organic growth factors be obtained?
From the environment
113
What are four types of organic growth factors?
Vitamins, amino acids, purines, pyrimidines
114
What are essential organic compounds that an organism can't synthesize?
Organic growth factors
115
Can organic growth factors only be obtained from the environment?
Yes
116
Vitamins, amino acids, purines, and pyrimidines are examples of these
Organic growth factors
117
What is a biofilm?
Microbial community comprised of a thin, slimy layer encasing bacteria that adheres to a surface
118
What do biofilms form?
Slime or hydrogels
119
What is a hydrogel?
Complex polymer containing many times its dry weight in water
120
How do bacteria communicate in a biofilm?
Via quorum sensing
121
What do bacteria secrete to attract other bacterial cells?
Inducer (signaling chemical)
122
These are microbial communities of bacteria encased in a thin, slimy layer that adheres to a surface
Biofilms
123
This is a complex polymer containing many times its dry weight in water
Hydrogel
124
What is quorum sensing used for?
Bacterial cell-to-cell communication
125
What do bacteria use inducer (signaling chemical) for?
Attracting other bacterial cells
126
Do bacteria in biofilms share nutrients?
Yes
127
What three things do biofilms shelter bacteria from?
Desiccation, antibiotics, and immune system
128
Do biofilms hinder the transfer of genetic information?
No
129
These allow bacteria to share nutrients
Biofilms
130
These shelter bacteria from harmful environmental factors such as desiccation, antibiotics, and the immune system
Biofilms
131
These facilitate the bacterial transfer of genetic information (e.g. conjugation)
Biofilms
132
What are two places biofilms can be found?
In digestive system and in sewage treatment systems
133
How much more resistant to microbicides do biofilms make bacteria?
1000x resistant
134
Are biofilms involved in 30% of infections?
No
135
Are biofilms involved in 70% of infections?
Yes
136
What are 4 examples of medical equipment inserted into the body that can form biofilms?
Catheters, heart valves, contact lenses, dental caries
137
These are found in the digestive system and in sewage treatment systems
Biofilms
138
These are 1000x resistant to microbicides
Biofilms
139
These are involved in 70% of infections
Biofilms
140
Catheters, heart valves, contact lenses, and dental caries can all be colonized by these
Biofilms
141
What is a culture medium?
Nutrient material prepared for microbial growth in a laboratory
142
What does sterile mean?
Containing no living microbes
143
What is inoculum?
Microbes introduced into a culture medium to initiate growth
144
What is a culture?
Microbes growing in or on a culture medium
145
What is nutrient material prepared for microbial growth in a laboratory?
Culture medium
146
What means containing no living microbes?
Sterile
147
What is microbes introduced into a culture medium to initiate growth?
Inoculum
148
What is microbes growing in or on a culture medium?
Culture
149
What is agar?
Complex polysaccharide
150
What is agar used for?
Solidifying agent for culture media in petri plates, slants and deeps
151
Is agar generally metabolized by microbes?
No
152
At what temperature does agar liquefy?
100 degrees C
153
At what temperature does agar solidify?
-40 degrees C
154
This is a complex polysaccharide that is used as a solidifying agent for culture media
Agar
155
What are 6 components of a culture media?
Energy source, carbon source, nitrogen source, sulfur source, phosphorus source, and organic growth factors the organism is unable to synthesize
156
What is chemically defined media?
Media in which the exact chemical composition is known
157
What are fastidious organisms?
Those that require many growth factors provided in chemically defined media
158
Do fastidious organisms have complex/particular growth requirements?
Yes
159
What is complex media?
Media containing extracts and digests of yeasts, meat, or plants; exact composition varies
160
What are two examples of complex media?
Nutrient broth and nutrient agar
161
What type of organisms require chemically defined media?
Autotrophs
162
What type of organisms uses complex media?
Heterotrophs
163
In this type of culture media, the exact chemical composition is known
Chemically defined media
164
These organisms require many growth factors and have complex/particular growth requirements
Fastidious organisms
165
This type of culture media varies batch to batch and contains extracts of yeasts/meat/plants
Complex media
166
Nutrient broth and nutrient agar are two examples of this type of culture media
Complex media
167
Autotrophs require this type of culture media
Chemically defined media
168
Heterotrophs require this type of culture media
Complex media
169
What is reducing media used for?
Cultivation of anaerobic bacteria
170
What does reducing media contain?
Chemicals (sodium thioglycolate) that combine O2 to deplete it
171
Is reducing media heated to drive of O2?
Yes
172
Is reducing media typically a solid?
No
173
This media is used for the cultivation of anaerobic bacteria
Reducing media
174
This media contains a chemical (sodium thioglycolate) that combines O2 to deplete it
Reducing media
175
This media is typically a broth and is heated to drive off O2
Reducing media
176
What are capnophiles?
Microbes that require high CO2 conditions
177
Does media used for capnophiles contain high oxygen?
No
178
What does capnophile media resemble?
Conditions of intestinal tract, respiratory tract, and other body tissues
179
Do capnophile cultures contain a CO2 packet?
Yes
180
Do capnophile cultures contain a candle?
Yes
181
These microbes require high CO2 conditions and low oxygen
Capnophiles
182
Media for this type of microbes resembles the intestinal tract, respiratory tract, and other body tissues
Capnophiles
183
This type of culture media contains CO2 packets and candles
Capnophile culture media
184
What are the four biosafety levels?
BSL-1 through BSL-4
185
What does BSL-1 entail?
No special precations
186
What does BSL-2 entail?
Lab coat, gloves, eye protection
187
What does BSL-3 entail?
Biosafety cabinets to prevent airborne transmission
188
What does BSL-4 entail?
Sealed, negative pressure; "hot zone"; exhaust air is filtered twice through HEPA filters
189
This biosafety level is for basic teaching labs
BSL-1
190
This biosafety level requires a lab coat, gloves, and eye protection
BSL-2
191
This biosafety level requires seals, negative pressure, and HEPA-filtered exhaust air
BSL-4
192
This biosafety level is also known as "hot zone"
BSL-4
193
This biosafety level requires biosafety cabinets to prevent airborne transmission
BSL-3
194
This biosafety level requires no special precautions
BSL-1
195
What is selective media?
Media that suppresses unwanted microbes, encourages desired microbes
196
Does selective media contain inhibitors to suppress growth?
Yes
197
What is differential media?
Media that allows different colonies to distinguish on the same plate
198
Can some media be both selective and differential?
Yes
199
This type of media suppresses unwanted microbes and encourages desired microbes
Selective media
200
This type of media contains inhibitors to suppress growth
Selective media
201
This type of media distinguishes colonies of different microbes on the same plate
Differential media
202
What is enrichment culture?
Culture that encourages the growth of a desired microbe by increasing very small numbers of a desired organism to detectable levels
203
Is enrichment culture usually a liquid?
Yes
204
What is enrichment culture usually used to study?
Soil and fecal samples
205
This type of culture encourages the growth of a desired microbe by increasing very small numbers of a desired organism to detectable levels
Enrichment culture
206
What is a bacterial colony?
A population of cells arising from a single cell/spore or from a group of attached cells
207
What is another name for a bacteria colony?
Colony-forming unit (CFU)
208
What method is used to isolate pure bacteria cultures?
Streak plate method
209
Do clinical samples contain pure cultures?
No
210
Do clinical samples contain several different kinds of bacteria?
Yes
211
This is a population of cells arising from a single cell or spore or from a group of attached cells
Colony
212
Colony-forming unit (CFU) is another name for this
Bacterial colony
213
What is the streak plate method used for?
To isolate pure cultures
214
What is a good method for short-term but not long-term bacterial culture storage?
Refrigeration
215
What is deep-freezing bacterial cultures?
Placing pure culture in suspending liquid and quick-freezing at -50 to -95 degrees Celsius
216
What is lyophiliziation?
Freeze-drying microbes by quickly freezing at -54 to -72 degrees and dehydrating in a vacuum (sublimation)
217
Is refrigeration good for long-term storage of bacterial cultures?
No
218
This is the process of placing microbes in suspending liquid and quick-freezing at extremely cold temperatures
Deep-freezing
219
This is the process of quickly freezing then dehydrating microbes in a vacuum
Lyophiliziation (freeze-drying)
220
What are four methods of microbe division?
Binary fission, budding, conidiospores, filament fragmentation
221
What type of division is typically used by bacteria?
Binary fission
222
What is generation time?
Time required for a cell to divide
223
What is the range for generation times for different bacteria species?
20 minutes to 24 hours
224
How does binary fission increase the number of cells each generation?
By 2 raised to the number of generations
225
How are bacterial growth curves represented graphically?
Logarithmically
226
This is the time required for a cell to divide
Generation time
227
This typically ranges from 20 minutes to 24 hours, depending on species
Generation time
228
Does binary fission quadruple the number of cells in each generation?
No
229
2 raised to the number of generations gives this
Total number of cells
230
Are bacterial growth curves represented arithmetically on graphs?
No
231
What is lag phase?
Time interval with no growth
232
What is log phase?
Period of bacterial growth/logarithmic increase in cell numbers
233
What is log phase also called?
Exponential growth phase
234
What is the stationary phase?
When the number of cells dividing equals the number of cells dying
235
When does the stationary phase happen?
As bacteria approach carrying capacity
236
What is carrying capacity?
The maximum number of organisms an environment can support
237
What is the death phase?
Period of logarithmic decrease in bacterial populations
238
What is the death phase also called?
Logarithmic decline phase
239
This is the time interval with no growth as bacteria are preparing to divide
Lag phase
240
This is the period of bacterial growth that results in logarithmic increase; also known as exponential growth phase
Log phase
241
This is the growth phase in which the number of cells dividing equals the number dying
Stationary phase
242
When bacteria approach carrying capacity, they enter this growth phase
Stationary phase
243
This is the maximum number of organisms that an environment can support
Carrying capacity
244
This is the period of logarithmic decrease in bacterial populations; also known as logarithmic decline phase
Death phase
245
What are four ways to directly measure microbial growth?
Plate count; filtration; most probable number (MPN); direct microscopic count
246
What do plate counts measure?
The number of colony-forming units on a solid medium
247
How many colonies are preferred to do a plate count?
30-300
248
What process must be done with the original inoculum to ensure the right number of colonies are on the plate?
Serial dilution
249
What are two methods to inoculate a plate with bacteria for counting?
Pour plate method and spread plate method
250
What does the pour plate method involve?
Inoculating empty plate with bacteria, then adding melted agar and swirling to mix
251
What does the spread plate method involve?
Inoculating a solid medium with bacteria, then spreading it over the surface
252
What is the purpose of serial dilution?
To ensure right number of colonies on medium to be counted
253
The pour plate method and spread plate method are two ways to do this
Perform plate counts
254
If 54 colonies are on a plate of 1:1000 dilution, what is the bacteria count from the sample?
54,000
255
How many mL are taken from each test tube in serial dilution?
1
256
Which method of preparing plates for plate counts results in colony growth in and on solidified medium?
Pour plate method
257
Does the spread plate method result in colonies growing only on surface of medium?
Yes
258
What method of direct microbial growth measurement is used when the quantity of bacteria is very small?
Filtration
259
What does filtration to measure microbial growth entail?
Passing solution through a filter to collect the bacteria then transferring to a petri dish
260
When is filtration used to measure microbes?
When the quantity of bacteria is very small
261
This method of microbial measurement involves passing solutions through a filter, then transferring to a petri dish
Filtration method
262
What is involved in direct microscopic count?
Placing a volume of bacterial suspension on a microscope slide and calculating the average number of bacteria per viewing field
263
What does direct microscopic count use to count cells?
A Petroff-Hausser cell counter
264
In direct microscopic count, what does the number of bacteria per mL equal?
The number of cells counted divided by the volume of area counted
265
This method of counting microbes involves placing a volume of bacterial suspension on a defined area of a microscope slide and calculating the average number of bacteria per viewing field
Direct microscopic count
266
In direct microscopic count, the number of cells counted divided by the volume of area counted equals this
Number of bacteria per milliliter
267
What are three indirect methods to estimate bacterial numbers?
Measuring turbidity, metabolic activity, and dry weight
268
How is turbidity measured to estimate bacterial numbers?
By measuring cloudiness of a sample with a spectrophotometer
269
How can metabolic activity be used to estimate bacterial numbers?
By measuring the amount of metabolic product, which is proportional to the number of bacteria
270
How is dry weight used to estimate bacterial numbers?
By filtering, drying, and weighing microbes
271
What type of organisms are measured using the dry weight method?
Filamentous organisms
272
This method of bacterial number estimation involves measuring cloudiness with a spectrophotometer
Turbidity
273
Is the amount of metabolic product proportional to the number of bacteria in a sample?
Yes
274
Is the dry weight method used for non-filamentous organisms?
No
