Lab #6 Flashcards
what is colony morphology
-with the naked eye: shape, edge, surface & elevation
What is coccus
round
what is bacillus
rod
what is spirillum
curved/coiled
what is diplo
2
what is strepto
chain
what is staphylo
cluster
Purple cells
gram +, rich in peptidoglycan
pink cells
gram -, rich in lipopolysaccharide
what does crystal violet do
stains peptidoglycan (especially in gr. +)
What does grams iodine do
application of mordant that forms an insoluble complex with crystal violet (fixes stain to cell wall)
What does Acetone-Alcohol do
dehydrates cell, traps crystal violet/iodine complex.
In gr.- it dissolves lipopolyssacharaide & washes away excess stain
what does safranin do
stains inner peptidoglycan coat for gr-. makes them pink
steps of staining
1) Water
2) Bacteria
3) Heatfix
4) crystal violet
5) Rinse
6) Iodine
7) Acetone-iodine
8) rinse
9) safarin
10) Rinse
what is a permissive agar
allows growth of anything
what is an indicator agar
organisms allows growth of any
blood agar plate
enriched media used to isolate organisms that require more nutrition
differential to detect hemolytic activity
B-hemolytic activity
complete lysis (clear zone)
Alpha-hemolytic activity
only partial lyse (green)
Y-hemolysis
no hemolytic activity
what is blood agar good for
differentiating streptococcus from staphylococcus
what kind will grow on macconkey agar
gram -, enteric bacteria
if it can eat lactose it shows its a gut bacteria
MAC agar contains…
bile salts (inhibit non enteric)
crystal violet dye (inhibit gram + bacteria)
neutral red dye (stains microbes fermenting lactose)
Lactose
Peptone
what does mac agar distinguish
lac + from lac -
If a bacteria is Lac +…
it means its enteric & it’ll be pink/ red
it produces acid that lowers the ph
if the bacteria is lac-
it means it cannot utilize peptone, forms ammonia raises ph so colonies are white
what is macconkey useful for
differentiating between salmonella & coli
what are aerobic bacteria
need O2 to grow
what are anaerobic bacteria
don’t need O2 to grow
no bacteria on MAC
bacteria are gram +, non-enteric or both
cannot grow b/c bile salts & crystal violet
what is MRSA
methicillin resistant staphylocccus aureus
what is VRE
vancomycin-resistant enteroccocus ( can live a long time on other objects too)
