Topic 10 Flashcards
(132 cards)
1
Q
What are the physical requirements for microbial growth?
A
- Temperature
- pH
- Osmotic pressure
2
Q
What are the chemical requirements for microbial growth?
A
- C source
- N source
- S source
- P source
- Organic growth factors
- Trace elements
- O2
3
Q
What is the maximum growth temperature?
A
50 degrees Celcius
4
Q
What is the optimum growth temperature?
A
approx 37 degrees Celcius
5
Q
What is the minimum growth temperature?
A
approx 4 degrees Celcius
6
Q
What temperature does Listeria monocytogenes grow at?
A
Low temperatures but growth is slowed
7
Q
What plays a role in gastric ulcers?
A
Helicobacterpylori
8
Q
What phile is Helicobacterpylori
A
Acidophile
9
Q
What phile is Bacteria?
A
Neutrophile
10
Q
What phile is Fungi?
A
Outside and inside Neutrophile
11
Q
What pH can Helicobacter pylori withstand?
A
Low pH conditions
12
Q
What happens in isotonic solution?
A
No water movement
13
Q
What happens in hypertonic solution?
A
- Water exits cell
ex: salt curing process
14
Q
Carbon (Chemical Requirements)
A
- For structural organic molecules
- Energy source
15
Q
Nitrogen (Chemical Requirements)
A
In A.As, proteins
16
Q
Sulfur (Chemical Requirements)
A
- In A.As, thiamine, biotin
- 4% dry weight of cell
17
Q
Phosphorus (Chemical Requirements)
A
- In DNA, RNA, ATP, and phospholipids (membranes)
- 4% dry weight of cell
18
Q
Organic Growth Factors (Chemical Requirements)
A
- Organic compounds the organism cannot synthesize on its own
- Usually not manufactured by the cell, must be obtained from environment
- Ex: vitamins, A.A, nucleotides
19
Q
Trace Elements (Chemical Requirements)
A
- Inorganic elements required in small amounts, mostly for specific enzymes
- Iron, Copper, Zinc, Magnesium, Calcium, etc
20
Q
What are the oxygen requirements?
A
It may vary with the organism
21
Q
What does oxygen do to energy generation?
A
It makes it more efficient however O2 can be lethal to some microbes
22
Q
What are obligate aerobes?
A
They require oxygen for survival and growth
23
Q
What are obligate anaerobes?
A
They cannot tolerate oxygen and cease to grow (and/or die) in the presence of oxygen
24
Q
What are facultative anaerobes?
A
They can survive in aerobic and anaerobic conditions but prefer to grow in the presence of oxygen
25
What type of medium do you observe aerobic and anaerobic growth in?
Thioglycolate broth medium
26
What oxygen can cause a highly destructive tissue infection?
Clostridium perfringens, an obligate anaerobe
27
What are the two anaerobic culture methods?
- "GasPak" anaerobic system (contains reducing media)
| - Anaerobic glove box
28
How do microbes grow in nature?
Often grow as biofilms
29
How are microbes grown in the lab?
May be grown as mixed cultures or pure cultures
30
What does liquid media (broth) contain?
A.A, salts, and nutrients that microbes need to grow
31
What is liquid media (broth) used for?
To culture bacteria and yeast (and protists)
32
What can agar be added to?
Nearly added liquid media - used to culture bacteria, yeast, mould
33
How are microbes solidified?
Using agar
34
What is agar?
A carbohydrate extracted from seaweed
35
What is a colony?
When one cell multiplies
36
What can colony morphology tell us?
The # of different species based on colour (same colour might be a different species though)
37
Why is streaking done?
You dilute a sample so that a single bacterium will grow as a colony
38
What are the bacteria within a colony like?
They are clones (genetically identical)
39
Explains what happens by the 3rd and 4th streaks?
As you go back and forth you are spreading less and less bacteria (you are diluting the amount of bacteria)
Hopefully by the 3rd and 4th streaks you will have individual cells
40
How can you grow a colony?
Isolate a pure genetic sample on solid media if it is diluted so that a single bacterium will grow a colony
41
Why do you culture viruses?
- To study virus particles
| - Vaccine production
42
How do we culture viruses?
- Viruses are obligate intracellular parasites (they can only grow in cells)
Therefore we must culture them in cells and not on dish plates
43
Where are bacteriophages grown?
On bacterial lawns
44
What is a plaque?
A hole that a virus has destroyed all that bacteria (happens as the virus replicates)
45
Do bacteriophages cause problems for humans?
No
46
What can we grow in egg cultures?
Animal viruses
47
How can you grow animal viruses?
May be grown in cell culture
48
What are the easiest cells to grow?
Cancerous cells (because they are non-differentiated (ex: not nerve or muscle cells) and they continuously divide rapidly
49
How can you use cells to make a virus grow?
Inject the cells with virus and have the virus grow
50
Are cell lines maintained?
Continuous cell lines may be maintained indefinitely (these cells lines are 'immortal' i.e tumor cells)
51
How are cancer cells different from other cells?
They can divide even if they are touching each other
52
Cancer cells and immortality
Some cancer cells are immortal (turn on genes) they do not die, they keep dividing
53
What is chemically define media?
The chemical composition is precisely known
54
What is an example of chemically defined media?
Minimal media
- contains only the bare essentials
- only certain species can grow
- often used to study genetic mutants
55
What is a type of non-selective media?
General or complex media
56
What does general or complex media encourage?
The growth of a range of microbes
57
What is complex media?
You are taking things and mixing things together but you don't know the exact portion of things
58
Describe enriched media (2)
- Non-selective
| - Contains additional factors needed to grow microbes with particular needs
59
Describe selective media
Only supports the growth of specific microbes
60
What type of cells does selective media allow to grow?
Gram (+) but not gram (-) cells
61
How many species grow with selective media?
One species
62
What grows on nonselective media
Everything grows
63
What is an example of selective media?
Pseudomonas Isolation Agar
- E.coli cannot grow
- Pseudomonas aeruginosa can grow
64
What conditions does fungi prefer?
Acidic
65
What temperature does fungi and bacteria like?
Fungi grow at lower temperatures (25) whereas bacteria like higher temperatures (37), bacteria and fungi compete with each other
66
Example of selective media (terms of bacteria or fungi)
pH of media may allow bacteria or fungi to grow
67
What pH does bacteria like?
pH 7
68
what pH does fungi like?
pH 6
69
Why do different species have a different appearance?
It is due to the characteristics of the medium (differential media)
70
How are X-gal and lactose related?
Anything that is capable of breaking down lactose can break down X-gal, it will break down and change colour
71
What is a type of differential media?
Media containing X-gal
72
How do blue colonies form?
When species/strains that can metabolize lactose (and X-gal) grow
73
What is the difference between non differential and differential media
Non-differential media: everything looks the same
Differential media: Species show differing reactions
74
What does EMB stand for?
Eosin methylene blue
75
What type of media is Eosin ethylene blue (EMB)?
Differential media
76
What does EMB media do?
Provides a colour indicator distinguishing between organisms that ferment lactose (eg. E. Coli) and those that do not (eg. Salmonella, Shigella)
77
Growth and colour with EMB media
It does not restrict the growth of certain bacteria but it makes them look different
We will see different colours based on how well they get broken down
78
What does MacConkey Agar contain?
Crystal violet, lactose, protein, and neutral red dye
79
What does crystal violet prevent from growing?
Gram (+)
80
What does crystal violet stick to?
Peptidoglycan therefore if you see growth it will be gram (-)
81
What growth will you see on a MacConkey Agar plate?
E. Coli: Yes
| Staph Aureus: No
82
What growth will you see on a nutrient agar plate?
E. Coli: Yes
| Staph Aureus: Yes
83
What type of plate type is MacConkey Agar?
Selective and differential
84
What happens if lactose is broken down on a plate?
There's a colour change
85
What 2 things can you figure out from growth on a MacConkey Agar plate?
1. If we are dealing with gram (-) or gram (+)
| 2. If it is something that can break down lactose
86
When is red dye present (MacConkey Agar)
Neutral red dye becomes red in the presence of the waste products of lactose metabolism - differential
87
What occurs in Alpha (group B) in blood agar?
Break down and oxidation of hemoglobin
88
What occurs in Beta cells (group A - streptococcus) in blood agar?
Capable of breaking down the RBCs completely, we are left with a clear area
89
What occurs in Gamma (group D) in blood agar?
No breakdown
90
What appearance do intact RBCs show in blood agar?
A nice overall red colour
91
What appearance do broken RBCs show in blood agar?
They become clear and get clear around the cells (differential)
92
What is enriched blood agar?
Blood supports additional microbes
93
Blood agar and sheep blood
It contains 10-20% whole sheep blood
94
What can you do in the hospital in terms of swabing?
There is an effective/rapid way to take swabs and get a sense of the diversity in the area and get a sense of the geno you are dealing with
95
How fast does E.Coli divide?
Very quickly (every 20 mins)
96
List the order of bacteria from fastest growing to slowest?
- E.Coli
- Staph Aureus
- Mycobacterium TB
- Mycobacterium leprae
- Treponema pallidium
97
How does bacterial replication occur?
Binary fission
98
What happens during the lag phase (Bacterial Growth Curves)
Very little change in growth, lots of metabolic activity
99
What happens in stationary phase (Bacterial Growth Curves)
- Metabolic rate drops, build up wastes/toxins
| - Nutrients used up
100
What are the phases in Bacterial Growth Curves?
1. Lag Phase
2. Log (Exponential) Phase
3. Stationary Phase
4. Death Phase
101
What happens in the log (exponential) phase in Bacterial Growth Curves?
- Binary fission
- Exponential growth
- Very sensitive phase (ABX)
102
What happens in the death phase in Bacterial Growth Curves?
Cell lysis (cell ruptures)
103
What happens to cell division speed after the lag phase? (Bacterial Growth Curves)
It divides very quickly
104
When are ABX quite effective to them?
Log phase (Bacterial Growth Curves)
105
When are they going to compete against each other? (Bacterial Growth Curves)
Stationary Phase
106
Why do the cell lyse during the death phase? (Bacterial Growth Curves)
They run out of food and waste builds up
107
What are the steps of Virus One-step Growth Curve?
- Attachement
- Penetration
- Biosynthesis/Maturation
- Burst Time
108
How can you measure microbial growth? (3 words)
Direct microscope count
109
What is direct microscope count
Directly count the # of cells in a knwon volume using a counting chamber (hemacytometer)
110
What is the advantage of direct microscope count?
- Can give a good # of how many cells
- Inexpensive
- Don't need special reagents
(Traditional way but now it can be done with equipment)
111
What is the disadvantage of direct microscope count?
- Tedious
| - May not be able to tell if the cells are alive
112
How can you measure microbial growth? (2 words)
Plate count
113
What is plate count?
The suspension of cells is mixed with or spread on agar
114
What are the advantages of plate count?
Viable cells form colonies which are easily counted
115
What are the two plate methods
The pour plate method and the spread plate method
116
Which of the two plate methods are more popular?
The spread plate method
117
Each colony is the product of ___
A single bacterium
118
What is fecal coliform count?
Used to examine water samples for contamination due to human waste
119
How is fecal coliform count done?
A water sample is passed through a filter which is then placed on selective media (which then grow as colonies)
120
How can you measure microbial growth (T)
Optical Density (Turbidity)
121
What is optical density (turbidity)?
- Cells scatter and absorb light
| - Shine light through a culture sample and measure how much is transmitted using a spectrophotometer
122
What will the Sepctrophotometer tell us about cells?
They will tell us how many cells are present but will not tell us if they are alive or dead
123
What is serial dilution?
Used if the sample is very concentrated (eg. if you were counting bacteria in a liquid culture)
- Are able to tell how many bacteria were in the original sample by working bacteria and tell the starting concentration
124
In what factor does dilution work (Serial Dilutions)
Each time you are reducing the # of bacteria by a factor of 10
125
How would you collect a sample of diseased tissue?
Surgical removal (biopsy)
126
How would you collect a specimen from the lung?
Either sputum dislodged by coughing or acquired via a catheter
127
How would you get a sample of urine?
Either sterile technique from a catheter or "clean catch" method when peeing which should be midstream
128
How would you get a sample from the stomach?
Intubation (inserting a tube into the stomach or an NG)
129
How would you get a sample of CSF?
Needle aspiration from subarachnoid space of spinal column
130
How would you get a sample of blood?
Needle aspiration from vein; anticoagulants are including in the specimen tube
131
How would you get a sample of skin?
Sterile swab brushed across the surface while not touching the neighbouring tissue
132
What replication process is good if you are growing bacteria in the lab
Binary fission
