Lab 3-11 5-28 4-1 4-4 Flashcards
What is Brownian motion?
Microbe collisions with water molecules.
Microbes vibrate in place, not swim
With wet mount and hanging mount looking for motility, what could cause a false negative?
Water dries up.
Too many microbes on slide - no room to move.
If a culture is too old or cold.
How is a wet mount made?
By placing a drop of water on a slide and covering it with a cover slip
How can motility be best observed?
using low or high-dry lenses
How is a hanging drop slide prepared?
Depression slide with a petroleum jelly ring.
Droplet is hanging on cover slip and not toughing the slide.
What is tetrazolium salt, TTC, used for?
Looking for red formazan motility positive
What does MacConkey agar contain?
Lactose, bile salts, neural red, and crystal violet.
A differential medium.
At what pH does Neural red indicate?
Indicates red at pH less than 6.8 - acidic conditions
What is the pH range for fermentation?
Acidic - lactose fermentation
What microbe does MacConkey agar detect?
Enterobacteriaceae to ferment lactose
What does eosin methylene blue, EMB, contain?
Gelatin, lactose, eosin Y and methylene blue
What is EMB used for?
Fecal coliform
What is the application for wet mounts and hanging drop technique?
To observe cellular motility
Which microbe is motility an important characteristic?
Enterobacteriaceae
What is phenylethyl alcohol agar, PEA, used for?
To isolate staphylocci and streptococci
