Lab 2

Question 1

Describe the following colony margins from left to right

Answer 1

circular, irregular, filamentous, rhizoid

Question 2

Describe the following colony margins from left to right

Answer 2

entire, undulated, lobate, curled, filiform

Question 3

describe the following elevation patterns from left to right

Answer 3

flat, raised, umbonated

Question 4

Describe the following elevation patterns from left to right

Answer 4

crateriform, convex, pulvinate

Question 5

what type of stain is this? What are the blue cells what are the pink/purple cells

Answer 5

Acid fast stain
Blue- non-acid fast
Pink/purple- acid fast

Question 6

what stain is this and what are the steps

Answer 6

Capsule stain
1. Use India ink, Congo red, nitrgrosin or eosin stain- stain capsules
2. Air dry
3. Flood with crystal violet or methylene blue- will stain cells but not capsules

Question 7

what stain is this and what are teh steps

Answer 7

Endospore stain
1. air dry and heat fix organism nd cover with blotting paper or towel
2. Saturate blotting paper with malachite green and steam over burner for 5 minutes while keeping paper moist by adding more dye
3. Wash slide in tap water
4. Counter gain with safari in , wash with water and then blot dry

Question 8

describe the potassium hydroxide test, how to do it, what is happening, what bacteria is most likely if positive

Answer 8

1. Add drop of KOH to loop full of bacteria on slide
2. KOH interact and degrade peptidoglycan layer producing viscous solution
3. If viscous solution occurs most likely gram negative bacteria (thin peptidoglycan layer)

Likely not gram positive due to thick peptidoglycan layer

Question 9

how does the catalase reaction work, how do you do it, what does it tell you

Answer 9

1. Add a drop of 3% hydrogen peroxide and a loop full of bacteria
2. If the bacteria has the catalase enzyme bubbling will occur—> positive test

Question 10

How does the coagulase test work, what do you do, how to interpret results

Answer 10

1. transfer 1 colony into a tube with 0.5mL of serum and incubate
2. positive result will have coagulated plasma that is unable to be resuspended with shaking
3. Negative result will be in liquid state

Question 11

how does the oxidase test work, what does it tell you

Answer 11

1. Place a loop full of bacteria onto oxidase paper
2. If it turns purple it contains enzyme- cytochrome C oxidase which is found in many aerobic and facultative bacteria

Question 12

What test is this

Answer 12

Potassium hydroxide test- positive shows vicious solution- typical of gram negative bacteria

Question 13

what test is this

Answer 13

Catalase test- bubbling is positive

Question 14

What test is this

Answer 14

Oxidase test- purple= positive