5: Killing Bacteria Flashcards
Fecal matter
80% bacteria
mostly gram positives anaerobesf found in intestine (most not disease causing)
colon bacteria
uncultureable outside of human gut
firmicutes and bacteriodetes
2 main groups of bacteria in fecal matter
Germ free mice…
no bacteria in gut
hard to gain weight
lose lots of fluids
gut bacteria are good
provide vitamins and nutrients
do some metabolism
increase surface area of gut
fecal matter: what do we smell?
bacterial byproducts
negative association because eating it can kill us/make us sick
Waste treatment
remove–>isolate–>sediment–>purify
chlorine treatment of water
kills most bacteria
waste water treatment limitations
does not remove chemicals
like prozac, progesterone, antibiotics in water
no limitations on how much of these can be in water
the further you are from a water system…
the more chemicals that aren’t broken down there are in your water
look at slide 4
look at slide 4
Ways to kill bacteria
oxidation/reduction
membrane disruption
protein folding disruption
Sepsis
microbial contamination
Asepsis
absence of significant contamination
aseptic surgery techniques to prevent microbial contamination of wounds
sanitization
lower microbial counts on eating utensils/in water to drink again
Biocide/germicide
KILLs microbes
Bacteriostaisis
inhibiting, not killing microbes
used in food prep to prevent foods from growing bacteria w/o removing the bacteria
sterilization
removing ALL microbial life
commercial steriliztion
killing C. botlulinim endospires… think restaurant cleaning
Disinfection
Removing pathogens
bleach
can also kill us
antisepsis
removing pathogens from LIVING tissues (don’t harm living tissue)
iodine
disinfection vs. antisepsis
a choice… do we kill the host in order to kill all the bacteria?
Oxidation/Reduction
can mutate DNA
prevent/alter action of enzymes
Membrane Disruption
loss of proton motive force
loss of integrity
Protein folding disruption
temp and some chem change lowest nrg state of protein
causes misfolding or unfolding
Physical control of microbes
moist heat
dry heat
moist heat
autoclaving
common for food
high temp WITH moisture
how moist heat works
high temp disrupts breaks hydrogen bonds in proteins
cool back down: proteins refold in a non-functioning way
think eggs… denaturation and rearrangement of proteins
autoclave
121C for 30 minutes
steam under a great among of pressure
moist heat
used by hospitals, dentists, good tattoo parlors, labs, disposal of bio waste
autoclave is used to
STERILIZE things
will kill things that grow at room temperature
why use pressure in an autoclave
to keep liquids from boiling so we can sterlize them
Dry Heat
stimulates oxidation rxn
no moisture
covalent change… IRREVERSIBLE
oxygen overcomes potential nrg needed to react with chemicals.
heat allows it to stay spontaneous
where is human fecal matter
all over bodies… we’re constantly leaking
important to clean underwear
underwear
front line to controlling fecal bacteria
we don’t actually clean them well
examples of dry heat
burnt toast
bunsen burner
oven (cooks food by dry heat)
dry vs. moist heat
moist: proteins come back together
dry heat: irreversible
burtn toast
oxygen reacted with carbon molecs
produced CO2 and carbon compounds that are the black burnt part
dry heat and underwear?
ineffective
Pasteurization
71C for 15 sec
heat very briefly: don’t change it, just enough proteins are denatured (not all)
only kill PATHOGENIC bacteria
pathogen free, not sterile
autoclaving underwear
better than burning… stays the same but is sterilized
Examples of pasteurization
milk
beer
canned foods…heat long enough to kill spores to prevent spoilage
Napolean
won at life because he could can food and take it with him and it didn’t spoil
Pastureizing… what do we kill
we kill pathogenic bacteria and denaturizes SOME proteins
Filter Sterilization
non lethal removal of microbes
size exclusion…
pore size smaller than microbe
HEPA
High Efficiency Particulate Air Filter
huge filter than purrifies air
fume hoods
idea behind vacuums that remove microbes from air…eh
pastuerizing underwear
what we do if we wash in hot water and then dry… but not the most effective
filtering and underwear
not effective
advantages of filters
allows low temp removal of bacteria and viruses
keep proteins/enzymes functioning
MGD… cold filtered bevrages… doesn’t change taste
how filtering works
pass liquid through filter with holes smaller than your microbe
cons of filtering
viruses and clamydia are usually small enough to get through
Desiccation
remove all water
prevents microbial growth but does NOT kill
freeze drying food… good for preservation
downsides to desiccation
many spores are resistant to it
some viruses are very resistant to it
does not kill bacteria in any way… just inhibits
Dessication and underwear
we also do this… dryer (dessication) to drawer (storage)
when and why is dessication useful?
preserving things (freeze drying)
Radiation
electromagnetic nrg
ionizing radiation
non-ionizing radiation
ionizing radiation
Gamma Rays
X rays
high nrg electrons
short wavelenght, high nrg
non-ionizing radiation
UV light
sponge in the sun
shortish wavelengths, highish nrg
microwaves
heat water molecules
photons excite water molecules
long wavelenght, low nrg
radiation depends on wavelength
wide spectrum
long wavelength: lower nrg
radiowaves
don’t kill anything
long wavelenght, lowest nrg
Infrared…
can kill bacteria… but not the best at it
UV light
causes damage to DNA
X-rays and Gamma Rays
do most of the sterilization
high nrg waves
as rays go through cell… they cause oxygen to react with protein and DNA of cell
protein becomes inactive
DNA is mutated
Underwear in the sun
leave it out for a long time inside out… really good way to sterilize
(used to do with clothes lines)
What is the best way to prevent foodborne illnesses
irradiation
kills EVERYTHING and still tastes the same
but no one will buy that food because people think its bad
(its not bad… it doesnt make the food radioactive)
irradiation
expose the thing to electormagnetic waves
place food near radioactive thing, doesnt make food radioactive, just kills all the microbes
microwaving
