Microbiology Lab Quiz #2

Front 1

Streak Plate Technique

Back 1

Spreads a bacterial culture over the surface of a plate

Label
Divide into 4 quadrants
Spread innoculum throughout first quadrant
Flame loop, start in old quadrant, pass from old to new 3 times
Spread culture only in new quadrant
Repeat for Q3 & 4
Incubate

Front 2

Streak Plate Purpose

Back 2

Purify mixed culture
Check culture to determine if it is contaminated

Front 3

Viable count

Back 3

Only considers number of LIVE, colony-forming cells

Front 4

Viable count procedure

Back 4

Perform a serial dilution
Add 0.1 - 1 ml to media plate by pour or spread plating
Incubate plates
Count number of colonies/plate
Calculate

Front 5

Serial dilution--why?

Back 5

To make the necessary calculations, you need isolated colonies. The number of cells in the original sample is often very large, so need to dilute in order to get a smaller amount

Front 6

Colony

Back 6

Pile of (ideally) genetically identical cells (=clones) that (ideally) originated from one cell. Cells are microscopic, colonies are macroscopic.

Front 7

Bioluminescent bacteria

Back 7

Vibrio and photobacterium

Photobacterium species live in Flashlight Fish; receive nutrients from fish and in return provide a unique device for frightening would-be predators

Front 8

Enzyme the produces visible light

Back 8

Lucierase

Front 9

Bioluminescent organism used in lab; grows within what organism?

Back 9

Vibrio Fisheri

Colonizes and grows in light organ (head region) of Hawaiian bobtail squid

Front 10

Thioglycollate Media

Back 10

Ingredients:
Yeast extract, dextrose (provide nutrients)
Low amount agar
Thioglycollate (reduces O2 to H2O)
Resazurin (O2 indicator + O2 -> pink; -O2 colorless)

Purpose: Determine O2 requirement of bacterium, grow anaerobic organisms

Differential Media

Results
Bacteria on top: obligate aerobe
All over: Facultative aerobe
Midway: microaerophile
On bottom: strict aerobe

Front 11

Blood agar plate

Back 11

Ingredients:
TSA + 5% sheep's blood

Differential Media

Purpose: ID bacteria that produce hemolysin (toxin that lyses many cell types including RBC)
Help ID streptococcus pyrogenes (strep throat)
BAP is a rich media that facilitates growth of fastidious (hard to grow) bacteria

Results:
Alpha hemolysins - green halo around growth (enterobacter aerogenes)
Beta hemolysins - lyse RBC's which CLEARS RBCs on plate (streptococcus aureus)
No hemolysis - No change

Front 12

Snyder Media

Back 12

Ingredients: Low pH
Glucose
pH indicator (bromcresol green)
Agar

Purpose: Determine if person has bacteria in mouth that can cause tooth decay (dental carries) and if so, to what degree.

Differential (glucose fermentation, low pH) and Selective (media has ingredients that inhibit growth of some organisms and enhances growth of others)

Results:
+ = yellow
- = green

Front 13

Anaerobic jar

Back 13

Purpose: growth of obligate anaerobes in petri

How? Chamber with sealed lid
Gas generator pack releases H2 and CO2, H2 reacts with O2 --> H2O
Pallidium catalyst
O2 indicator strip, Methylene blue

Results:
+O2 --> blue
-O2 --> colorless

Front 14

Beta hemolysis

Back 14

staphylococcus aureus

Front 15

Majority of flora in throat is which type?

Back 15

Alpha

Front 16

hemolysin

Back 16

toxin secreted from cell, destroys RBC

Front 17

Hemolysis

Back 17

destruction of RBCs

Front 18

Differential media

Back 18

distinguishes one microorganism type from another growing on the same media

Front 19

Selective media

Back 19

Used for growth of only select organisms

Front 20

Bacteria responsible for dental carries

Back 20

lactobacilli, oral streptococci