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UCD 3 Microbiology Chp 3
third chapter of the book
49
Veterinary Medicine
Undergraduate 3
09/24/2010

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Cards

Term
Name some of the conditions and considerations when growing bacteria
Definition
moisture, temperature, pH, nutrients (organic and inorganic), ossmotic pressure, atmosphere (gases, pressure etc)
Term
What are the five phases of a bacterial growth curve
Definition
Innoculation, lag (adaptive) phase, log (exponetial/growth) phase, stationary phase, decline (death phase)
Term
What is a chemostat
Definition
a special growth chamber that maintains the exponential phase by supplementing nutrients and filtering off waste
Term
How would you count the number of cells present
Definition
direct smear or counting chamber
Term
What is a CFU
Definition
colony forming unit
Term
How do you count CFU's
Definition
Spread plate, Pour plate, Miles-Misra (from 5 drops), Membrane filtration (then culture membrane)
Term
What other methods are there for counting bacteria
Definition
Opacity tubes (McFarlands tubes as reference for total cell count), electronic count (total cell count)
Term
What is a chemotroph and what types are there
Definition
A chemotroph gets the energy it needs from the chemicals in its environment as opposed to the sun, chemoheterotrophs, chemoautotrophs
Term
What are the main features of a chemoautotroph
Definition
Obtains energy from using chemicals as an energy source as aside from the sun, can synthesise all the parts it needs from carbon found in the environment
Term
What are the main features of a chemoheterotroph
Definition
Obtains energy from using chemicals as an energy source as aside from the sun, cannot synthesise all the parts it needs from carbon found in the environment, must absorb some of its organic molecules
Term
What are some of the nutrients needed by chemoheterotrophs
Definition
peptones source of peptides, amino acids, sulphate, phosphate, calcium, iron, magesium, potassium
Term
What is sulphate needed for by bacteria
Definition
certain amio acids
Term
What is phosphate needed for
Definition
nucleic acids and certain energy metabolites
Term
Name four co factors for bacterial enzymes
Definition
Calcium, iron, magnesium, potassium
Term
Psychrophiles
Definition
low temperatures, 15 *C
Term
Mesophiles
Definition
body temperature, (20-45 *C)
Term
Thermophiles
Definition
60*C
Term
pH preference
Definition
neutral
Term
What determines ossmotic pressure needed
Definition
cell wall
Term
Bacteria in Hypotonic solution
Definition
cell lyses by swelling
Term
Bacteria in hypertonic solution
Definition
cell shrinkage
Term
Example of a bacteria which prefers hypertonic
Definition
staphlycoccus aureus prefers 7.5% NaCl
Term
Aerobes
Definition
need oxygen
Term
Microaerophiles
Definition
like a little oxygen
Term
faculative anaerobes
Definition
can grow with or without oxygen
Term
obligate anaerobes
Definition
can only grow without oxygen (fermentors!)
Term
capnophiles
Definition
CO2
Term
How do you incubate anaerobes
Definition
jar with special envelope (add H2O => H2 and CO2 released => H2 binds O2), light a candle (less precise), ascorbic acid
Term
How do you incubate capnophiles
Definition
special envelope in a jar
Term
Short term preservation of bacteria
Definition
sub culturing, risk of contamination and mutation
Term
Long term preservation of bacteria
Definition
freeze drying (lyophilization), liquid nitrogen (-190 *C), freezing (-70 *C)
Term
What important consideration is there when freeze drying (lyophilization)
Definition
Needs to be in a vacum to avoid cell lyses during dessication
Term
Cryoprotectants
Definition
Dimethyl sulphoxide and glycerol
Term
What temperature should bacteria not be stored at long term
Definition
-20 *C
Term
What state should bacteria be in for long term storage
Definition
hypobiotic state
Term
Something obvious enough and important when selecting bacteria for long term storage
Definition
use younger cultures! They do better
Term
Bacterial inactivation
Definition
inhibition and sterilisation
Term
Methods of inhibition
Definition
refridgeration, freezing, boiling, pasteurisation, acidification, osmotic pressure increase (sugar or salting), vacum packs (only aerobes), irradiation
Term
Short term refridgeration
Definition
4 *C
Term
Short term freezing
Definition
-20 *C
Term
boiling
Definition
100*C
Term
Pasteurisation
Definition
72*C for 15 min
Term
Sterilising techniques
Definition
autoclave, dry heat, incineration, gamma radiation, flaming, UV light, membrane filtration
Term
Autoclave specs
Definition
moist heat, 15 min at 121*C or 45 min at 115*C
Term
Dry heat specs
Definition
oven, 1-2 hours at 160 *C
Term
Incineration specs
Definition
1000 *C
Term
Gamma irradiation is not suitable for what
Definition
glass or metal
Term
What is important to remember about UV light as a sterilisation technique
Definition
no deep penetration
Term
What size membrane is needed for membrane filtration
Definition
0.22 micrometers
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