labs 6-10 Flashcards
simple stain
using only one stain
direct stain
uses simple stain and stains cells
negative stain
uses simple stain and stains background only
beaded
bacteria not stainded evenly so dark spots appear
bipolar staining
spots of stain on end of cell
basic dyes(direct staining)
postively charged(cation) chromophores colour negative bacterial cells
acid dyes(negative staining)
negatively charged (anion) chromophores repelled by negatve bacteria cells so stain positive background
smear
thin layer of bacterial cells onto slide and air dry
heat fixed
apply heat to smear which shrinks bacteria and helps it stick on if too much then cells wrap
vortex
swirling liquid in tube
turbidity
cloudiness of broth
if light bacterial growth do
8-10 loops
if heavy bacterial growth do
4-6 loops
differential stain
distinguishes between various microorganisms according to how they take dyes (2dyes)
gram stain
type of differential showing gram positive(purple thick peptidoglycan) or negative(pink thin peptidoglycan)
primrary dye and counterstain for gram
crystal violet and safrain
iodine is what in gram stain
mordant trapping agent that increases cells desire for stain by binding with primary and becoming larger than it insoluble complex
what does decolourizer do
it makes pores in cell wall allowing dye to come out for thinner ones pores bigger so comes out faster but in thicker ones the spores are smaller so comes out less
3 advantages of negative staining
helps us see bacteria that resist stain, no need for heat fix so do not shrink and see actual size, and can be used on bacteria too delicate for heat fixing
capsules
slimy layer around cell that is neutral so does not take in dye using negative allows us to see since glows and counterstaining cells helps see better
negative stain example
nigrosin
endospore
allows bacteria to survive in poor conditions
germination
once environment better bacteria returns to vegtative or growing state
endospore staining
resist dye unless heat applied so it can penetrate spore coat
schaeffer fulton endopsore stain
uses heat to force primary stain malachite green into spores and water used as decolourizer then counterstained with safrain
steps of endospore stain
paper on slide, flood with malachite green, apply heat for 5 mins, cool for 1 min, apply water for 15-30 secs, use safrain wait fro 1 min, then rinse
aerotolerance
indicate ability or inability of organism to grow with o2
obligate aerobes
bacteria only grow with o2
facultative anaerobes
bacteria grow better with o2 but still grow without
obligate anaerobes
grow only without o2 cause o2 has two unpaired electrons and makes lots of toxic o2
enzymes obligate aerobes have and faculitative
superoxide dismutase and catalase kills compenets made by toxic o2
aerotolerant anaerobes
cannot use o2 but not harmed by it
microaerophiles
need reduced amount of o2 and increased amount of co2 for growth
excluding o2 use
Gas pak anaerobic system with chems that release hydro and co2 when air comes with lid in place they react and form water and removes free o2 with wayer droplets on side methyelene blue indicator turns with no o2 and blue if there is
reducing media
contains reagents that chemically combine with free o2 reduces concentration of o2
fluid thiol medium contains
sodium thiol(combines o2 to remove from broth), small amount of agat increases viscosity to make it more difficult for air to diffuse, and redox potential indicator to show free o2 turns pink when oxidized and colourless when reduced
