Ch. 6 Flashcards
(68 cards)
1
Q
microbial growth
A
increase in population of microbes due to reproduction
2
Q
results of microbial growth
A
discrete colony
biofilm
3
Q
discrete colony
A
an aggregation of cells arising from single parent cell
4
Q
biofilm
A
collection of microbes living on a surface in a complex community
5
Q
growth requirements
A
nutrients such as carbon, oxygen, nitrogen, and hydrogen
6
Q
carbon based organisms
A
autotrophs
heterotrophs
7
Q
energy based organisms
A
chemotrophs
phototrophs
8
Q
electron based organisms
A
organotrophs
lithotrophs
9
Q
organotrophs
A
acquire electrons or hydrogen atoms from organic molecules
10
Q
lithotrophs
A
acquire electrons or hydrogen atoms from inorganic materials
11
Q
toxic forms of oxygen
A
singlet oxygen
superoxide radicals
peroxide anion
hydroxyl radical
12
Q
obligate aerobe
A
- grows only when O2 is available
- requires O2 for respiration
- produces superoxide dismutase and catalase
e. g. Bacillus, Pseudomonas
13
Q
facultative anaerobe
A
- grows best when O2 is available, but also grows without it
- fermentation or anaerobic respiration
- produces superoxide dismutase and catalase
e. g. Escherichia coli, Saccharomyces (yeast)
14
Q
obligate anaerobe
A
- cannot grow when O2 is present
- does not use O2
- does not produce superoxide dismutase or catalase
e. g. Clostridium, Bacteroides
15
Q
microaerophile
A
- grows only if small amounts of O2 are available (2-10%)
- requires O2 for respiration
- produces some superoxide dismutase and catalase
e. g. Helicobacter pylori
16
Q
aerotolerant anaerobe
A
- grows equally well with or without O2
- does not use O2
- produces superoxide dismutase and catalase
e. g. lactobacilli
17
Q
psychrophiles
A
-5 to 15 celcius
live in snowfields, ice, cold water
no human pathogens
18
Q
mesophiles
A
20-40 celcius
majority of bacteria
19
Q
thermophiles
A
45-80 celcius
compost piles, hot springs
20
Q
hyperthermophiles
A
80-110 celcius
usually members of Archaea
21
Q
physical requirments
A
temperature
pH
water
22
Q
neutrophiles
A
grow best in narrow range around neutral pH 6.5-7.5
23
Q
acidophiles
A
grow best in acidic habitats
24
Q
alkalinophiles
A
live in alkaline soils and water
25
physical effects of water
osmotic pressure
| hydrostatic pressure
26
osmotic pressure
pressure exerted on a semipermeable membrane by a solution containing solutes that cannot freely cross the membrane
27
halophiles
an organism, that grows in or can tolerate saline conditions.
28
hydrostatic pressure
water exerts pressure in proportion to its depth.
29
barophiles
live under extreme pressure
30
differing associations
antagonistic
synergistic
symbiotic
31
quorum sensing
cause of biofilm formation
| process by which bacteria measure their density in an environment by utilizing signal and receptor molecules
32
pure cultures
composed of cells arising from a single progenitor (or colony forming unit, CFU)
aseptic technique using streak or pour plates
33
culture media
nutrient broth
| agar
34
types of culture media
```
defined
complex
selective
differential
anaerobic
transport
```
35
defined media
e.g. glucose, water, Na2HPO4, CaCl2, etc.
36
complex media
exact chemical composition unknown
nutrients derived from breakdown of yeast, beef, soy, and proteins
useful when nutritional needs unknown
37
selective media
contain substances that favor or inhibit growth of particular microorganisms
38
enrichment culture
selective medium used to increase small numbers of a microbe to observable levels
39
cold enrichment
enrich a culture with cold-tolerant species.
40
fastidious bacteria
organisms require a large number of growth factors
41
selective media e.g. mannitol salt agar
has NaCl which only lets halophiles grow (Staphylococci)
42
selective media e.g. MacConkey agar
contains bile salts, crystal violet which inhibits most non-intestinal bacteria and gram positive bacteria, but lets gram negative cells grow
43
differential
differentiates between two or more genera or species
| has a constituent that causes an observable change (a color change or change in pH) when a biochemical reaction occurs
44
differential media e.g. MacConkey agar
lactose differential agent
45
differential media e.g. blood agar
pattern of hemolysis:
| alpha, beta, gamma
46
alpha-hemolysis
partial hemolysis of red blood cells
47
beta-hemolysis
complete hemolysis of red blood cells
48
gamma-hemolysis
no hemolysis
49
special culture techniques
animal and cell culture
| low-oxygen culture
50
animal and cell culture
used when artificial media is inadequate
| viruses only grow within living cells
51
low-oxygen culture
carbon dioxide incubators mimic the environment of certain body tissues.
candle jars create environment with low oxygen and high CO2 levels
52
preserving cultures
refrigeration (short period)
deep-freezing (years)
lyophilization (decades)
53
growth of microbial population
1. most unicellular microorganisms reproduce by binary fission
2. bacterial growth is measured by an increase in the number of cells
3. many bacteria can divide every 30 minutes, and a single cell will result in a population of about 1 million cells in 10 hours.
54
generation time
time required to for a population to double in number.
Ex. Escherichia coli (E. coli) double every 20 minutes
Ex. Mycobacterium tuberculosis double every 12 to 24 hours
55
phases of microbial cell growth
lag phase
log phase
stationary phase
decline phase
56
lag phase
adjustment phase
57
log phase
1. once adapted, population growth occurs at an exponential or logarithmic rate
2. more susceptible to antimicrobial drugs
3. signs and symptoms of disease
58
stationary phase
1. number of dying cells equals the number of cells being produced.
2. nutrients are depleted and waste products are accumulated
59
decline phase (death)
as waste products build, and nutrients deplete, bacteria begin to die in increasing numbers
60
estimating number of microorganisms
1. determine severity of certain infections
2. determine effectiveness of food preservation techniques
3. measure the degree of contamination of water supplies
4. evaluate disinfectants and antibiotics
61
direct methods not requiring incubation
coulter counter
| flow cytometry
62
coulter counter
counts cells as they interrupt an electrical current
63
flow cytometry
detects changes in light transmission as cells pass a detector
64
direct methods requiring incubation
serial dilution, viable plate counts
membrane filtration
most probable number
65
indirect methods
turbidity
metabolic activity
dry weight
molecular methods
66
turbidity
more = greater population
67
molecular methods
isolate DNA sequences of un-culturable prokaryotes by polymerase chain reaction and DNA hybridization
68
molecular methods advantages
highly specific
faster no culture required
generic no media required
