Chapter 9 Flashcards
(78 cards)
1
Q
minimal medium
A
chemically defined medium
2
Q
complex medium
A
chemically non-defined medium
3
Q
culture
A
nutrient media that allows microorganism to grow
4
Q
heterotrophs
A
rely on other organisms to make the organic compounds that they use as carbon sources
5
Q
autotrophs
A
use the CO2 discarded by heterotrophs to make complex cell constituents made up of C, h, and O, such as carbs
6
Q
phototrophs
A
extract energy from absorption of light
7
Q
chemotrophs
A
extract energy from oxidation-reducation reactions that remove electrons from high energy compounds to produce lower energy compounds
- lithotrophy
- organotrophy
8
Q
nitrogen
A
- critical component of proteins, nucleic acids, and other cellular consituents and is required in large amounts by living organisms
- N2 makes up nearly 79% of Earth’s atmosphere, but the nitrogen in N2 is unavailable for use by most organisms
- Nitrogen from N2 must be “fixed” or sonverted to ammonium ions (NH4+) through the nitrogen cycle
9
Q
obtaining nitrogen
A
- nitrogen is removed from air and converted to ammonia
- ammonia is converted to nitrate
- nitrogen is removed from nitrate and converted to nitrogen gas
10
Q
extremophile
A
microorganism that lives in extreme conditions
11
Q
binary fission
A
- how most bacteria grow
- one parent cell splits into 2 equal daughter cells
- ## before dividing, cell grows and increases number of cellular components
12
Q
formation of septum during division
A
- bacteria must divide after doubling genetic information
- z ring defines the division plane between 2 daughter cells
- septum divides 2 daughter cells (where cell wall and outer membranes are remodeled)
13
Q
budding
A
- buds formed at extreme ends of microorganism
- offspring develop and grow into a mother cell
- release of daughter cells= mother cell dies
14
Q
lag phase
A
- no increase in number of living bacterial cells
- cells gearing up for next phase of growth–> cells grow larger and are metabolically active
15
Q
log phase
A
- exponential increase in number of living bacterial cells
16
Q
stationary phase
A
- plateau in number of living bacterial cells; rate of cell division and death roughly equal
0 waste builds up and oxygen becomes limited
17
Q
death/decline phase
A
- exponential decrease in number of living bacterial cells
18
Q
batch culture
A
- closed system
- no inflow of nutrients/outflow of waste
19
Q
continuous culture
A
- in open system
- fresh medium is continually added to a culture and an equal amount of culture is constantly siphoned off
- bacterial populations can be kept in exponential phase at a constant cell mass for long periods of time
20
Q
chemostat
A
continuous culture system in which the diluting medium contains a growth-limiting amount of an essential nutrient
- microorganisms are constantly in exponential growth
- ex: human GI tract
21
Q
biofilm
A
complex, dynamic ecosystem that forms on a variety of environmental surfaces
- highly structured communities
22
Q
biofilm growth
A
- cellular flagella attach to the monolayer
- microcolonies form
- cells produce exopolysaccharides (EPSs)
- the biofilm matures
- the biofilm dissolves and cells disperse
23
Q
biofilm structure
A
- extracellular polymeric substances (EPS)
- channels
microcolonies
streamers
24
Q
physical requirements for growth
A
- pH, temperature, moisture, hydrostatic pressure, osmotic pressure and radiation
25
chemical requirements for growth
- availability of carbon, nitrogen, sulfur, phosphorus, trace elements, organic compounds, oxygen
26
hyperthermophile
growth above 80 degrees C
27
thermophile
growth from 50-80 degrees C
28
mesophile
growth between 15 and 45 degrees C
29
psychrophile
growth below 15 C
30
alkaliphile
growth above pH 9
31
neutralophile
growth between pH 5 and 8
32
acidophile
growth below pH 3
33
halophile
growth in high salt
34
strict aerobe
growth only in oxygen
35
facultative microbe
growth with or without oxygen
36
microaerophile
growth only in small amounts of oxygen
37
strict anaerobe
growth only without ixygen
38
barophile
growth at high pressure
39
barotolerant
growth between 10 and 500 atm
40
minimum growth temperatures
- lowest temperature when organism can survive and replicate
41
optimum growth temperature
when growth rates are highest
42
maximum growth temperature
highest temperature when growth can occur
43
water activity
- how water availability is measured
- quantity approximated by concentration
- interactions with solutes lower water activity
- more solutes in a solution= less water is available for microbes to use for growth
44
osmolarity
- a measure of the number of solute molecules in a solution
- the more particles in a solutions, the greater the osmolarity and the lower the water activity
45
plasmolysis
- cells shrink because molecules move out
- caused by hypertonic environments or an increase in salt or sugar
46
extreme/obligate halophiles
require high osmotic pressure
47
facultative halophiles
tolerate high osmotic pressure
48
concentration of hydrogen ions
- has a direct effect on cell's macromolecular structures
- extreme concentrations of H+ or OH- ions in solution will limit growth
- pH can alter protein shape, which in turn changes protein activity
49
pH homeostasis mechanisms
- E. coli can reverse proton influx by importing a variety of cations such as K+ and Na+
- under extremely alkaline conditions the cells can use Na+/H+ anti-porters to recruit protons into the cell in exchange for expelling Na+
- some organisms can change the pH of the medium by using various amino acid decarboxylases and deaminases, producing alkaline and acidic products, respectively
50
aerobes
- use oxygen as a terminal electron acceptor in the ETC to extract energy trapped in nutrientns and convert it to a biologically useful form
51
aerobic repiration
use of O2 as the terminal electron acceptor
52
anaerobes
- oxygen is toxic
- most microbes are anaerobic, growin buried in the soil, within anaerobic digestive tract, within biofilms on teeth
53
anaerobic respiration
- using ETC without oxygen as the terminal electron acceptor
54
facultative anaerobes
possess enzymes to detoxify oxygen radicals and also the machinery for both fermentation and aerobic respiration
55
aerotolerant anaerobes
use only fermentation to provide energy but contain superoxide dismutase and catalase or peroxidase to protect them from reactive oxygen species
56
microaerophiles
will grow only at low oxygen concentrations
- possess a decreased level of superoxide dismutase and/or catalase
57
capnophiles
microorganisms that thrive in the presence of high concentrations of carbon dioxide
58
problem with oxygen
- powerful oxidant and can oxidize numerous chemicals in the cell, leading to cell injury or death
59
hydrogen peroxide
broken down by catalase
60
superoxide
broken down by superoxide dismutase
61
agar
- complex polysaccharide
- used as solidifying agent for culture media in petri dishes, slants, deeps
- not metabolized by microbes
- liquifies at 100 C
- solidifies at 40 C
62
selective media
encourage the growth of certain microorganisms and discourage others
- will have growth inhibiting additive, such as bile salts, crystal violet or an antibiotic, which will limit growth on the medium to only those organisms that are desired
63
differential media
enable different species to be distinguished from each other
- ex: Mannitol salt
64
enrichment media
encourage the growth of a specific organism
- enriched= lots of nutrients= grows bacteria that are fastidious/hard to grow in lab
65
Mannitol Slat
- selective medium
- high concentrations of salt, contains mannitol and phenol red
- differentiates different types of Staph (halophiles)
- staph aureus can ferment mannitol= yellow
66
MacConkey Agar
- selective medium
- crystal violet, neutral red and bile salts and lactose
- selects for organisms that grow in presence of bile salts
- differentiates between organisms that can ferment lactose (ferments lactose= color change)
67
differential medium
- ex: blood agar
- allows for differentiation of particular chemical reaction yield an observable characteristic associated with the growth a particular organism/group of organisms that are able to grow on the medium
68
blood agar
- differential medium
- distinguishes bacterial species that can break down the red blood cells included in blood agar medium
- typically used to differentiate between streptococcus species
69
beta hemolysis
complete lysis, resulting in a clear zone around the colony
70
alpha hemolysis
partial lysis
- resultingin greenish coloration around the colony
71
gamma hemolysis
- no lysis
- no color change
72
pure cultures
- one bacterium gives rise to one colony
73
total cell counts
- accounts for all cells, regardless of viability and culturability
- useful for monitoring overall microbial load in a sample
- may not accurately represent potential for infection/food spoilage
74
ciable cell count
- accounts for cells capable of reproducing and forming colonies
- crucial for assessing food safety, water safety, and pathogenicity
- used to evaluate the effectiveness of sterilization and antimicrobial treatments
75
enumeration of bacterial cells without a microscope
can be accomplished with an electronic instrument called a florescence-activated cell sorter (FACS) which can count and separate bacterial cells with different properties
76
turbidity estimation of bacterial numbers
- population can be calculated by measuring the turbidity of a cell culture
- the degree to which the liquid medium has become cloudy because of microbial growth
77
turbidity
can be measured in real time using a spectrophotometer, which passes a beam of light through a sample of the culture
78
optical density
the decrease in intensity of light due to the scattering of light is measured as optical density
