3: Microbial Growth II Flashcards
Haemophilus Inflenzae
DOES NOT cause flu
Does cause:
- pneumonia, bacteremia (bacteria reproduces in blood: TSS), meningitis, otitis media (not fatal)
Haemophilus Inflenzae vaccine
protects against type B (Hib)… most virulent
works against the strucutre of the capsule
John’s Hopkins sad story
head of the hospital made a vacciene… which didn’t work
what is the fridge temp
4C
Why 4C?
highest density of water at this temperature
we want to keep things cold but not freeze. So we want water to be dense… if freezing happens it only happens on top
Are there bacteria that can spoil food at 4C?
YES! But not a ton. and growth is slow
but mostly fungus
Freezers:
-20C and thawing over night
thawing lets growth happen for half an hour, then refreezes
Why do humans die when we freeze them?
ice crystals… cells burst
Pasteurizatin
go above 60C: denaturation and of breakdown lipid membranes.
Go from medium zone to denaturation then quickly back down
The colorful pool
Each color is a different ecosystem of bacteria at a different temperature
Thermoaquaticus
TAC (for PCR)
useful in labs
Ocean vents
at the mid-Atlantic ridge where plates are moving apart.
no light… nrg taken from high energy of electrons coming out of vent
likely earliest life on earth
2 miles under the ice
liquid water that is bellow 0C.
lots of bateria
The main point…
if there is water, there can be life!
life needs one thing above all else
LIQUID WATER
pH requirements… most life
between 6.5 and 7.5
in our bodies
Why use high and low pH?
for long term storage
Prevention (not elimination) of growth
What is most affacted by changes in temperature and pH?
DNA, RNA, or enzymes
enzymes! Think proteins
the amino acid sequence doesn’t change, just the organization
DNA and RNA are very stable
Can life survive in anhydrous places?
NO! theres no water, and life can’t function without water
making pickles and sauerkraut
using bacterial acid production to preserve food
products of fermentation
done before refridgeration was a thing
Acidophiles
some live at pH of 4
chemoautrotrophs live at pH of 1
mud pools: very acidic soil. also near copper mines
Chemoautotrophs
use sulfer reduction to generate nrg
pH of 1
Osmotic Pressure
Salt to preserve food
inside cells salt conc: 1% or 1g/100ml
NaCl and KCl
plasmolyzed
when a cell is collapsed bc of lack of water inside (hypertonic solution)
if a cell is in hypertonic solution
it is NOT dead, just static/inert
what else can be used to make a hypertonic solution?
SUGAR
Does a spoonful of sugar help the medicine go down?
NO! it prevents the antibiotic from getting into bacteria
cheese
acids from bacteria make milk proteins curdle
addition of salt makes it resistant to microbial growth (does not inhibit fungal growth)
why cheese flavors are different?
its about culturing different types of bacteria in milk
creamy cheeses
due to fungus enzymes modifying proteins
Chemical requirements of bacterial life
Trace elements organic compounds carbon Nitrogen, sulfer phosphorus Oxygen
Trace elements
minerals: Fe, Cu, Mg, Mn
iron: cytochromes in ETC… life evolved in solution w/ lots of irron and copper: not so much now.
We have to put lots of nrg into keeping them around.
iron conc in body low: inhibits survival of many bact.
Get trace minerals from SEA SALT
Organic compounds
vitamins
we can’t produce them: have to consume them to survive
oxygen:
is in water and disolveable in atmosphere
some don’t need it the same way we do
Carbon
lots of different main types… some have genes to break down more tyepes than others…
USE THIS for pure cultures
Cellulose vs. Starch
animals can’t break the bond of cellulse
- cows and termites have the right ecosystem to have beacteria that do. WE DO NOT
How do humans break down starch then?
amylase in mouth
Nitrogen
in the air… none of that is useable by humans
ability to break down nitrogen bond on earth in general is super rare
Needed by all life
Nitrogen cycle
bacteria in soil can deal with nitrogen: make gas useable
we have enzymes that can deal with some of the byproducts of oxidized or reduced nirgrogen.
Vovox…
the babies live in the mother
only mother can fix nitrogen
the secrete of dynamite
no oxygen required
mix high and low level nitrogen… BOOM
Sulfer
some amino acids need it:
Cysteine and methionine
Needed by all life
phosphorus
part of nucleic acid back boes
Needed in ATP
Needed by all life
Arsenate Experiment
aresinic is similar to phosphorus… can it replace it?
We need at least 1% phosphorus… but 99% can be replaced
functionally DNA could pretty much still reproduce without it
can’t COMPLETELY replace it
5 groups of oxygen
Obligate Aerobes Facultative anaerobes Obligate anaerobes Aerotolerant anaerobes Microaerophiles
2 things to know about nitrogen
it is fixed by soil bacteria
nitrogen is required by all life
Obligate Aerobes
NO fermentation
REQUIRES oxygen to survive
can deal with ox radicals
grow on skin… all over body
Facultative anaerobes
uses oxygen to produce lts of nrg
CAN ferment. can survive w/o oxygen
can deal with ox radicals
us, lots of places of body… pretty much everywhere
Obligate anaerobes
ONLY grow in ABSENCE of oxygen… bc of radicals
cannot deal with ox radicals
grow in gut
Aerotolerant anaerobes
doesn’t care about oxygen. DOESN’T use it, CAN live with it
CAN deal with oxygen radicals
grow all over body
Microaerophiles
requires LOW concs of oxygen
grows in lungs
CANNOT deal with radicals
grow in lungs, vaginal cavity, carries (cavities)
compare facultative anaerobes and aerotolerant
FA:
Aerotolerant:
PLEASE look at table on slide 24
PLEASE look at table on slide 24
how do we culture bacteria … Pure culture
create situation where only the requirements of the organism of interest are met
non-selective media
undifined in character… lots grow but not all
rich: BHI, LB
blood agar, chocolate agar
selective media
only a few can grow
MAC with bile salts and selects for enteric bacteria (e. coli)
Broths
liquid media
Plates
semi-solid liquid
