Exam II Flashcards
(291 cards)
1
Q
What three conditions can affect microbial growth?
A
Different temperatures
different pH levels
different osmotic pressures
2
Q
What are the cardinal temperatures?
A
minimal
optimal
maximal
3
Q
What are the classification of organisms based on their cardinal temperatures?
A
Hyperthermophiles Thermophiles Mesophiles Psychrotrophs psychrophiles
4
Q
Psychrophiles can only grow at temperatures less than _______.
A
20 C (-5 to 20)
5
Q
Psychrotrophs typically have a growth range of ____ to ______
A
0 to 30 C
6
Q
What percentage of bacteria can grow <= 10 C
A
80%
7
Q
Psychrophiles can be found in ____ ____, _______, and ________.
A
alpine soils, icefields, oceans
8
Q
Psychrophiles are not human __________
A
pathogens
9
Q
Psychrotrophs can be found in ___, _____ ____, and in ______
A
soils, surface water, foods
10
Q
Psychrotrophs can be human ______
A
pathogens
11
Q
Mesophiles have a typical range for growth of ___ to ____
A
15 to 40 C
12
Q
Mesophiles have an optimal temperature that is approximately normal _____ _____ temperature.
A
human body
13
Q
Mesophilic bacteria can be human _______
A
pathogens
14
Q
Thermophiles have a typical range of growth of ____ to _____
A
40 to 75 C
15
Q
Hyperthermophiles have a typical range for growth of ____ to _____
A
65 to 110 C
16
Q
Thermophiles can be found growing in ____ ____
A
hot springs
17
Q
_______ can be isolated from ocean floor thermal vents/ridges.
A
hyperthermophiles
18
Q
pH is the concentration of _______ ions in a solution
A
hydrogen
19
Q
pH is measured on a _______ scale from 0-14 based on the hydrogen concentration
A
logarithmic
20
Q
pH =
A
-log[H+]
21
Q
Pure water is considered ______ and was assigned a pH of _____. This means that water has 10^-7 moles of H+ ions per liter.
A
neutral; 7
22
Q
As the concentration of H+ increases, the pH _____ and the solution becomes more _____
A
decreases; acidic
23
Q
As the concentration of H+ decreases, the pH _____ and the solution becomes more ______
A
increases; basic
24
Q
What are the three classifications of organisms based on the growth pH range?
A
Acidophile
Neutrophile
Alkaliphile
25
Acidphiles grow well in acidic environments with a pH of <=
4.5 to 5.5
26
Alkaliphiles grow well in basic enviroments at a pH of >=
8 to 8.5
27
Acidophiles can be found growing in such places as ____ ____ _____ and the _____
acid mine drainage; stomach
28
Alkaliphiles can be found in the soil of ____ ____ or in places like the shores of Mono Lake, California where the pH is 10
alkali flats
29
Neutrophiles grow well at a neutral pH between ___ and ___
5.5; 8
30
Most human ______ are neutraphiles since most bodily fluids are at neutral pH.
pathogens
31
_____ is required by all forms of life including bacteria?
Water
32
For bacteria ______ is necessary to maintian ____ pressure
water; turgor
33
______ pressure is the pressure inside a cell that is required for survival
turgor
34
If the correct turgor pressure is not maintained a bacterium could _____ (rupture) or ______ (shrink).
lysis; plasmolysis
35
To regulate turgor pressure, bacteria maintain high concentration of ____ and ______ ions in their cytoplasm
potassium; sodium
36
High concentrations of potassium and sodium ions within the cell and lower concentrations of these ions outside the cell creates a _______ ______.
concentration gradient
37
formation of a concentration gradient leads to ______
osmosis
38
what is the movement of water from an area of low solute concentration to an area of high solute concentration in order to achieve equilibrium?
Osmosis
39
What is the force with which water flows from an area of low solute concentration to an area of high solute concentration?
osmotic pressure
40
What are the three types of osmotic environments a bacteria could encounter
Hypotonic
Isotonic
Hypertonic
41
In hypotonic enviroments, there is a _____ solute concentration inside the cell than outside which creates a ____ osmotic pressure, and water moves _____ the cell which causes the cell to ____.
higher; low; into; lysis
42
In isotonic environments, there is ______ solute concentration inside and outside the cell and water moves in and out of the cell at an ______ rate.
equal; equal
43
In hypertonic environments, there is a ____ solute concentration inside the cell than outside which creates a ____ osmotic pressure, and water moves ____ of the cell which causes the cell to ______.
lower; high; out; plasmolysis
44
The concentration of _____ in a solution can affect osmotic pressure.
Salt
45
Most bacteria survive and grow in salt concentrations
3%
46
Bacteria that grow optimally at salt concentrations > 3% are called what?
Halophiles
47
Extreme halophiles can ONLY survive at salt concentrations between ____ and ____.
15%; 25%
48
What type of bacteria can survive and grow over a wide range of salt concentrations?
Osmotolerant
49
Halophiles are used in the fermentation of foods products such as _____ ____.
soy sauce
50
What is the ability or inability to live in the presence of O2?
aerotolerance
51
What must have O2 to survive and grow?
obligate aerobes
52
What can grow in the presence or absence of O2?
facultative anaerobes
53
What do not need O2 but can survive in the presence of O2?
Aerotolerant anaerobes
54
what survive only when O2 levels are low?
microaerophiles
55
what can only survive when CO2 levels are high?
capnophiles
56
What can O2 kill?
obligate anaerobes
57
What removes most free O2 from media; however; as the media cools oxygen starts to diffuse back into the media?
autoclaving
58
when media is in a tube the diffusion of O2 back into the broth or agar results in a ______ ______
concentration gradient
59
the surface of the media in a tube will have a high O2 concentration while the media at the bottom with have ____ O2.
no
60
Bacteria will grow where the O2 _______ in the tube is optimal for that organism
concentration
61
____ media is used in an agar deep stab to ensure that the bottom of the tube is anaerobic.
more
62
bacteria are stabbed once all the way to the ______ of the tube with an inoculating needle
bottom
63
What are the important ingredients in fluid thioglycollate medium?
sodium thioglycollate
L-cystine
resazurin
64
What is the purpose of sodium thioglycollate?
reducing agent (reduces O2 to water)
65
What is the purpose of L-cystine?
reducing agent (reduces O2 to water
66
What is the purpose of Resazurin
oxidation-reduction indicator
turns red/pink in the presence of O2
straw color in the absence of O2
67
Tubes of aerotolerant organisms will appear what?
cloudy all over
68
facultative anaerobes will be appear how in a tube?
concentrated at top but growth throughout
69
Obligate anaerobes will grow where in a tube?
only at bottom
70
Obligate aerobes will grow where in a tube?
only at top
71
what are used to produce anaerobic conditions required for aerotolerance examination of plates?
GasPack
72
The GasPak become activated by exposure to air and ______ is produced
CO2
73
How long does it take for anaerobic conditions to be reached with a GasPack?
around 2.5 hours
74
Methylene blue strip or tablet turns what color in the presence of O2?
blue
75
Wht is the most common reason anaerobic conditions were not achieved?
not proper sealing; hole in plastic bag
76
The majority of bacteria are what in terms of oxygen tolerance?
anaerobic
77
are most anaerobic bacteria pathogens?
No
78
Anaerobic chambers are often used to study _____
anarobes.
79
Bacteria replicate by what?
Binary fission
80
What is the time taken to get from 2^x to 2^(x+1)
doubling/generation time
81
Nf =
Ni*(2^n)
82
The average doubling time is generally between what?
20 to 60 minutes
83
environmental factors like temperature, pH, and nutrient availability can have a direct impact on the _____ ____ of an organism.
doubling time
84
in a laboratory setting the effects of various environmental factors on a bacterium's growth rate can be examined using a _____ _____ ______.
Closed Growth System
85
A closed-growth system is an environment in which ____ nutrients are added and ____ waste products are removed
no;no
86
How many distinct phases of growth can be observed in a closed growth system and what are they?
4, Lag, Logarithmic, Stationary, Death
87
Which phase is the initial phase of the growth curve where the organisms are acclimating to a new environment?
Lag Phase
88
During which phase is there no cell division but is a time of high metabolic activity in preparation for growth?
Lag
89
The more drastic the change in the environment, the longer the ____ phase is.
Lag
90
After a bacterium is acclimated to a new environment, it begins to divide during which stage?
Log
91
During what phase is the maximum growth rate exponential and at regular intervals of time?
Log
92
When the number of bacteria versus time is plotted on a ___ ____ the ascending straight line on the curve represents the exponential growth phase.
log scale
93
You can determine the generation time using which phase?
Log
94
Which stage do nutrients become limited and the waste products begin to accumulate leading to an unfavorable environment?
Stationary
95
Which phase does the growth rate equal the death rate?
Stationary
96
The length of the stationary phase can vary among _____ bacterial species
different
97
During which phase are all the nutrients depleted and the levels of waste products toxic?
Death
98
During which phase do bacteria begin to die faster than they grow?
Death
99
Depending on what will the death occur at rapid rate or be gradual?
the bacterial species
100
If bacteria die but do not _____ there may not be a loss of turbidity and a obvious death phase will not be observed unless viable plate counts are done
Lysis
101
A bacterial growth curve can provide the length of time the bacterium is in each ____ ____.
growth phase
102
A bacterial growth curve can provide the ______ growth conditions of a bacterium
optimal
103
A bacterial growth curve can provide the mean _____ ____ of the organism
generation time
104
Bacteria replicate using what?
Binary fission
105
Nf equals what?
Ni2^n
106
Environmental factors like what have a direct impact on the doubling time of an organism?
Temperature, pH, and nutrient availability
107
The average doubling time for bacteria is what?
20 to 60 min
108
What is used to observe the effects of various environmental factors on a bacterium’s growth rate?
Closed growth system
109
In a closed growth system, ______ nutrients are added and ______ waste products are removed.
No; no
110
What are the direct methods to measure the growth of bacteria
Plate counts
Filtration and plate counts
Most probably number (MPN)
Direct counting
111
What are the pros and cons of plate counts?
Pros - measures # of viable cells
Cons- time consuming and assumes that each bacterium grows and divides to produce a single colony
112
What are the pros and cons of filtration and plate counts?
Pros - measures # of viable cells in a small quantity
Cons - time consuming and assumes that each bacterium grows and divides to produce a single colony
113
What are the pros and cons of most probable numbers?
Pros - can be used for bacteria that cannot grow on solid media
Cons - only a statement that there is a 95% statistical chance that a bacterial population falls within a certain range
114
What are the pros and cons of direct counting using manual counting?
Pros - very accurate and relatively inexpensive
| Cons - very tedious and time consuming
115
What are the pros and cons of direct counting using electronic cell counters?
Pros - very accurate and results obtained relatively quickly
Cons-expensive equipment that requires significant training in order to operate
116
What are some indirect ways to measure the growth of bacteria?
Metabolic activity
Dry weight
Turbidity
117
What indirect method assumes that the amount of the metabolic product is directly proportional to the # of bacteria present?
Metabolic activity
118
What is one of the quickest, easiest, and most common method for assessing bacterial growth?
Turbidity
119
What device is used to measure turbidity?
Spectrophotometer
120
What kind of beam of light is used to measure the percent transmittance or absorbance
Monochromatic
121
What is transmittance?
The fraction of incident light that passes through a sample
T= intensity of light out/intensity of light in
Produces an exponential curve
122
What is absorbance and what is it equal to?
The quantity of light that a sample neither transmits nor reflects; Optical density
123
What kind of relationship exists between absorbance and concentration?
Linear
124
Absorbance ranges from what to what?
0 to 1.99 A
125
If a sample is 1.99 A or above what should you do to it?
Dilute it
126
If a sample is diluted 1:5 and the absorbance of this diluted samples is 0.8 A. What was the absorbance of the original sample?
0.8 * 5 = 4
127
Each McFarland standard represents a specific what?
Bacterial cell concentration
128
How do you plot a standard curve using McFarland Standards?
Plot Absorbance vs Concentration
129
The Oxidation-Fermentation Test determines what?
What catabolic pathway a bacterium can use to break down a carbohydrate
130
What are examples of catabolic pathways?
Aerobic respiration
| Fermentation
131
In Aerobic respiration what is the final electron acceptor and what is required in the environment.
O2; oxygen
132
In fermentation what is the final electron acceptor and what can it occur in the presence or absence of?
Organic molecule; O2
133
Aerobic respiration occurs only in the presence of what?
Oxygen
134
During aerobic respiration a small amount of what are produced?
Acidic intermediate compounds
135
In fermentation large amounts of what are produced?
Acidic compounds
136
What are the two important media components of oxidation fermentation medium?
A carbohydrate
PH indicator like Bromthymol blue
137
The initial pH of the OF medium is ______ and the color of the medium is _______.
7.1; green
138
If the pH drops to _______ the media turns what color?
6; yellow
139
In order to produce an anaerobic environment to promote fermentation, the top of the OF medium can be overlayed with what?
Sterile mineral oil
140
If an organism can only use the oxidation pathway then the color of the OF tube overlayed with sterile mineral oil will be what?
Green
141
If an organism can only use the oxidation pathway, then in the presence of oxygen the OF tube will show that a moderate amount of acidic compounds were produced so the media will be what color only at the top?
Yellow
142
If an organism is capable of fermentation or fermentation and oxidation then the OF tube either overlayed with mineral oil or exposed to oxygen will be what color?
Yellow
143
If an organism is a weak fermenter then the OF tube that is both covered with mineral oil or exposed to oxygen will be what color?
Yellow at the top of both
144
If the organism cannot metabolize the carbohydrate in the OF tube then both the mineral oil covered tube and the tube exposed to oxygen will be what color?
Green
145
What test is used to determine what carbohydrate a bacterium can ferment?
Phenol Red broth test
146
The end products generated by fermentation are what?
Alcohols, acids, and gas
147
What are the three important points to remember about the fermentation pathway?
1. Glucose is not the only carbohydrate that can be used in glycolysis
2. The end products of fermentation include acidic compounds
3. Gas can also be an end product of fermentation
148
Is phenol red broth considered a differential media?
Yes
149
What are the important media components of phenol red broth?
1. It is purchased as a base broth that allows one to add any single carbohydrate for testing
2. Peptone which serves as a source of amino acids
3. Durham tube which is placed upside down in the broth to determine if a gas is produced.
150
The pH of the phenol red broth starts out as what which means the color of the media is what?
7.3; red
151
If the pH of phenol red broth drops to what the media turns what color?
6.8; yellow
152
If the pH of phenol red broth raises above what the media turns what color?
7.3 reddish-pink
153
If the bacterium can ferment the carbohydrate in the phenol red broth then the media will be what color?
Yellow
154
If the bacterium cannot ferment the carbohydrate in the phenol red broth then the media remains what color?
Red
155
If the bacterium cannot ferment the carbohydrate but breaks down peptone in the media then the media will turn what color?
Reddish pink
156
Both aerobic and anaerobic respiration consist of what 3 steps?
Glycolysis, the Kreb’s cycle, and the electron transport chain (ETC)
157
In what two steps are aerobic and anaerobic respiration identical?
Glycolysis and Krebs cycle
158
The difference in aerobic and anaerobic respiration during the ETC is what?
The final electron carrier
159
In Aerobic respiration what is the final electron acceptor?
O2
160
In anaerobic respiration what is the final electron acceptor?
Non oxygen final electron acceptor (SO4^2-)(NO3-)(CO3^2-)
161
The electron transport chain passes electrons down a chain of molecules that alternate between becoming what?
Oxidized and reduced
162
For aerobes and facultative anaerobes the final electron acceptor is or can be what?
Oxygen
163
Premature electron leakage can occur in the ETC which produces what?
Superoxide
164
A bacterium must be able to break down superoxide due to its to toxicity. What enzyme breaks down superoxide?
Superoxide dismutase
165
When superoxide dismutase breaker down superoxide, it produces what toxic compound?
Hydrogen peroxide
166
In order to survive when H2O2 is produced, organisms must be able to break down H2O2. What enzyme breaks down H2O2?
Catalase
167
The presence of catalase is determined by the production of what?
O2 gas
168
In protein catabolism proteolytic enzymes (proteases) are used to break down proteins into peptides and peptides down to their basic what?
Amino acid components
169
Specific what break down amino acids?
Enzymes
170
What is decarboxylation?
The removal of the carbonyl group of an amino acid
171
What is decarboxylase?
An enzyme that catalyzes the removal of an amino acid’s carbonyl group
172
What coenzyme is required for decarboxylase activity?
Pyridoxyl phosphate
173
What is a polyamine?
An organic compound with 2 or more primary amino (NH2) groups
174
Why are polyamines important?
- have role in the regulation of gene transcription and translation
- have role in biofilm formation
- associated with bacterial iron scavenging molecules
- involved in the bacterial response to low pH
175
The presence of what can help raise the intracellular pH?
Decarboxylases
176
Ornithine, lysine, and arginine decarboxylases are all regulated in a bacterium and are produced specifically under what conditions?
Acidic
177
The by-products of decarboxylase reactions are alkaline compounds that can be used to what?
Neutralize and raise the low intercellular pH
178
What medium is used for a decarboxylation text?
Moller’s decarboxylase base medium
179
What are the important components of Mollers decarboxylase base medium?
- beef extract and peptone
- pyridoxal phosphate (coenzyme required for decarboxylase activity)
- Bromcresol purple pH indicator
- media is initially between pH 5.2 -6.2 so it appears copper in color
180
What can be added to Mollers decarboxylase broth to test for a specific decarboxylase?
A large amount of a specific amino acid
181
If the decarboxylase media starts out at a neutral pH something must be done to create what?
An acidic environment
182
What pathway produces a large amount of acidic products that can lower the pH of media?
Fermentation
183
The decarboxylase media contains what, which many bacteria can use for fermentation?
Glucose
184
What conditions are the most favorable to promote fermentation of glucose?
Anaerobic conditions
185
If an organism cannot ferment glucose the color of the decarboxylation media will be what?
Copper
186
If an organism cannot ferment glucose under anaerobic conditions in the media the organism is considered what?
Decarboxylase indeterminant
187
If an organism can ferment glucose but the decarboxylase is not present then the decarboxylation media will turn what color?
Yellow
188
If then decarboxylation media turns yellow the organism is considered what?
Decarboxylase negative
189
If the organism can ferment glucose under anaerobic conditions and can decarboxylase the specific amino acid then the media turns what color?
Purple
190
If the decarboxylation media turns purple than the organism is considered what?
Decarboxylase positive
191
The last complex of the ETC is called what?
Cytochrome C oxidase (complex IV)
192
In a bacterium, cytochrome oxidase specifically transfers electrons from cyctochrome c to what?
O2
193
Cytochrome oxidase does what to cytochrome c and oxygen?
Oxides cytochrome c and reduces O2
194
What is a chromogenic reducing agent?
A chemical that can donate an electron to another molecule and in so doing undergoes a color change
195
What chromogenic reducing agent is used in an oxidase test?
Tetramethyl - p - phenylenediamine (TMPD)
196
What color does TMPD turn when it becomes oxidized?
Dark blue
197
If there is no color change during an oxidase test then the TMPD remains in a reduced form and the organism is considered what?
Oxidase negative
198
If the paper turns dark blue during an oxidase test then the cytochrome c oxidase was present and the organism is considered what?
Oxidase positive
199
TMPD is unstable so the test must be read within what?
20 to 30 seconds
200
If nitrate (NO3-) is used as the final electron acceptor then the bacteria can perform either what or what?
Nitrate Respiration (Denitrification) or Ammonification
201
What is denitrification?
A multi step process performed by a group of enzymes that leads to the production of nitrogen gas from NO3
202
What is ammonification?
A multi step process performed by a group of enzymes that leads to the production of ammonia from NO3
203
The first step of either denitrification or ammonification is what?
The reduction of nitrate (NO3) to nitrite (NO2)`
204
What enzyme reduces nitrate?
Nitrate reductase
205
What is the purpose of the nitrate reduction test?
To determine if an organism can use nitrate for either denitrification of ammonification
206
What are the key components of a nitrate broth?
Potassium nitrate (KNO3)
A Durham tube
The broth is clear prior to inoculation
207
If the organism used in a nitrate test is a non fermentor as determined by a fermentation test (OF or phenol red broth) then the gas must be produced through what?
Denitrification
208
If there is gas in the nitrate reduction test then the organism is what? What is the source of gas? What is the gas?
Non-fermentor; denitrification; nitrogen gas
209
If an organism produces gas in the nitrate reduction test the organism is determined to be what?
Nitrate reductase positive
210
If the organism was determined to be a fermentor from an OF test then the type of gas produces is what?
Unknown
211
If there is growth overnight but no gas produced or gas production occurred and organism is a fermentor, what must be added to the culture?
Sulfanilic acid and naphthylamine
212
After addition of sulfanilic acid and naphthuylamine the broth will turn red in color and the organism will be considered what?
Nitrate reductase positive
213
If the addition of the reagents to the nitrate reduction test produce no change in color what must happen?
Further testing
214
If after reagents are added to a nitrate reduction test and there was no change in color, what can be added to catalyze the reduction of any nitrate source in the broth to nitrite?
Zinc
215
If the broth turns red after zinc is added the organism is considered what?
Nitrate reductase negative
216
If after zinc is added to the nitrate reduction test there is no change in color, then the organism is considered what?
Nitrate reductase positive
217
What test determines whether a bacterium can perform mixed acid fermentation?
Methyl Red Test (MR)
218
What test determines whether a bacterium can perform 2,3-butanediol fermentation?
Votes Proskaur Test (VP)
219
Mixed acid fermentation produces what acids?
Lactic acid
Acetic acid
Formic acid
Succinct acid
220
MR and VP broths are the same and consist of what components?
Peptone, acts as a source of proteins
Glucose
Phosphate buffer which maintains the media at a neutral pH at low amounts of acid.
221
If after several drops of MR are added, at a pH of 4.4, the color will be what?
Red
222
If after several drops of MR are added at a pH of 6.2 the color will be what?
Yellow
223
If a bacterium can not perform mixed acid fermentation only a small amount of acid is produced so the color will be what?
Yellow
224
If bacterium can perform mixed acid fermentation, large amounts of acids are produced and the methyl red indicator will be what color.
Red
225
In 2,3-butanediol fermentation pyruvate is converted to what first and what second?
First acetoin and then 2,3-butanediol
226
Why cant a pH indicator be used to detect 2,3 - butanediol fermentation?
The acidic compounds quickly convert to neutral alcohols
227
The VP test detects what?
Acetoin
228
What two reagents are added to detect acetoin?
Alpha-naphthol and potassium hydroxide
229
When the reagents are added in the presence of acetoin what is produced?
Diacetyl
230
What color does the media turn if diacetyl reacts with guanidine form the peptone in the media?
Red
231
If no acetoin is present the color produced at the surface of the culture will be what color?
Copper
232
What are used to determine if a bacterium can survive and grow in the presence of a single carbon source or nitrogen source?
Nutrient utilization test
233
In a citrate utilization test what is used as the only carbon source and what is used as the only nitrogen source?
Citrate; ammonium phosphate
234
Citrate can enter the bacterium through the action of what enzyme?
Citrate permease
235
Once inside the cell citrate is broken down into what by what enzyme?
Oxaloacetate and acetate; citrase
236
Oxaloacetate is then converted to what which can be further broken own to produce energy?
Pyruvate
237
Ammonium phosphate is converted to ammonia and ammonia by-products which are all what?
Alkaline
238
What are the components of Simmons Citrate Agar
1. Defined media
2. Only carbon source is citrate
3. Only nitrogen source is ammonium phosphate
4. Contains pH indicator (bromothymol blue)
239
The initial color of a neutral citrate agar is what?
Green
240
If the citrate agar increases to a pH of 7.6 what color does it change to?
Blue
241
In a citrate utilization test, if there is no growth, no pH change the media will be what color and what does that mean the organism is defined as?
Green; citrate negative
242
If the organism grows but the media remains green during a citrate utilization test, then the organism is considered what?
Citrate positive
243
If the organism can utilize the nitrogen source then it will grow on the on the slant and the media turns what color? What is the organism defined as?
Blue; citrate positive
244
What is deamination?
The removal of the amine group from an amino acid
245
What is deaminase?
An enzyme that catalyzes the removal of an amino acid’s amine group
246
Specific deaminases act on specific what?
Amino acids
247
The removal of the amine group can produce what?
Pyruvate; acetyl-CoA; Krebs cycle intermediate compounds
Each of these products can be used to generate energy
248
Deamination reaction requires what?
The co-enzyme pyridoxal phosphate
249
Products of tryptophan deamination are what?
Pyruvate, ammonia and indole
250
what does an indole test use to determine whether a specific product has been made
Chemical reaction
251
What reagent is added to determine the presence of indole?
Kovac’s reagent
252
If indole is present, the color will change to what?
Red and will be along the surface
253
What components are used for the indole test broth?
Tryptone broth, consisting of amino acid produced front he break down of proteins by the enzyme trypsin
High concentration of tryptophan
Does not contain pH indicators
254
If an organism does not possess tryptophanase, then what is missing?
Red rosindole dye
255
IMViC tests are typically used to differentiate between what?
Indole
Methyl Red
Voges-Proskaur
Citrate
Enteric bacteria and/or coil forms
256
If indole and MR are negative, VP is either negative or positive, and citrate is either negative or positive what kind of bacteria is present?
Enterobacter
257
If Indole and VP are negative but MR is positive and Citrate is either positive or negative what type of bacteria might you have?
Salmonella
258
If indole is negative, MR and VP are positive, and Citrate is either negative or positive then the type of bacteria might be what?
Proteus
259
If the indole and MR tests are positive, the VP negative, and the citrate either positive or negative the bacteria may be what?
Echecheria
260
What is starch?
An extremely large polysaccharide made up of glucose molecules linked by glycosidic bonds to form very long chains
261
What are the two types of molecules that make up the structure of starch?
Amylose and amylopectin
262
Amylose is what?
A long chain of glucose molecules
263
What is amylopectin?
Branded chains of glucose molecules
264
What enzyme breaks down glycosidic bonds?
Alpha-amylase
265
What is the content of starch agar?
Starch
266
If bacteria have alpha-amlyase it will do what on the starch agar?
Secret it and diffuse into the agar
267
Iodine reacts with starch to produce what color?
Dark brown/black
268
Iodine does not react with what?
Glucose
269
If the agar around the bacteria still contains starch and is what color, the organism is determined to be what?
Dark brown/black; alpha-amylase negative
270
If the agar around the bacteria does not turn dark brown/black the the organism is considered what?
Alpha-amylase positive
271
What contains between 200 and 220 amino acids?
Casein
272
Casein is what type of protein?
Phosphoprotein
273
There are 4 different types of casein which account for what percentage of the proteins found in cow’s milk?
Casein
274
What enzyme breaks down casein?
Casease
275
When secreted, casease can break the peptide bonds between what?
Adjacent amino acids
276
What is the component for milk agar?
Powdered nonfat milk
277
If there is not a color change on the milk agar the bacteria is determined to be what?
Casease negative
278
If there is a zone of clearing around the bacteria on a milk agar then the bacteria is determined to be what?
Casease positive
279
What is collagen?
A protein found mostly in fibrous tissues
280
What is gelatin?
Product from the hydrolysis of collagen
281
Gelatin is an abundant source of what?
Amino acids
282
What enzyme breaks down gelatin?
Gelantinase (a proteolytic enzyme)
283
What is the media used in the gelatinase test?
Nutrient gelatin
284
If the media remains solid after inoculation during a gelatinase test, the organism is determined to be what?
Gelatinase negative
285
If the growth media becomes liquified during a gelatinase test the organism is determined to be what?
Gelatinase positive
286
What is urea?
The product of the decarboxylation of certain amino acids
287
What is urease?
An enzyme present in certain bacteria that can hydrolyze urea into ammonia and CO2.
288
Because it is a basic compound, ammonia can do what within the bacterium?
Neutralize the acidic conditions
289
What are the important components of a urea broth?
A trace amount of yeast extract
Urea
Potassium phosphate (buffer)
Phenol red pH indicator
290
If the broth remains peach or slightly yellow during a urease test, the organism is determined to be what?
Urease negative.
291
If the urea in the broth is broken down then large amounts of ammonia will raise the pH and the phenol red indicator will turn what color?
Pink
