Micro Practical

When observing a stained slide, should the iris diaphragm be all the way open or closed?

All the way open

When observing a wet mount, should the iris diaphragm be open or closed

closed

Name 3 different ways you could describe a cultures elevation

raised, umbonate, convex

Name 3 ways you could describe a cultures shape

round, punctiform, filamentous

describe the purpose of aseptic transfer

prevent contamination of a pure culture when working with it

Does this tube have growth? If yes, what is it called?

Yes, turbidity

How would you describe Brownian movement?

vibrating type movement caused by the dynamic motion of molecules in a suspending liquid

What type of stain is this? What does it indicate?

This is a negative stain, the bigger the halo the larger the capsule produced.

What type of stain is used in a spore stain?

malachite green, counterstain is safranin

What type of bacteria will have a positive acid-fast test?

Mycobacterium

What type of oxygen requirements are A, C, and D

A: facultative anaerobe

C: Aerobic

D : Anaerobe

What is the pH indicator in Durham tubes?

phenol red dye

What results can you gather from this Durham tube?

It is positive for gas production, and positive for acidic byproducts

What results can you gather from this tube?

It is positive for deamination, indicating the production of ammonia, because the organism could not use the sugar source

What results can you gather from tube A?

It is positive for Indole production

What is the reagent in an Indole test?

Kovac’s reagent

What does a positive methyl red test indicate about the pH?

It indicates the pH is below 4.6

What does a peach color indicate in a Voges-Proskauer test?

production of neutral end products, acetylmethylcarbinol and butanediol

What is blood agar used for?

The detection of hemolysins

What results do plate C indicate?

alpha hemolysis, or incomplete hemolysis

what results do plate D indicate?

Beta hemolysis, or complete hemolysis

What is the fermentable carbohydrate in Vogel-Johnson plates?

Mannitol

What is the pH indicator in Vogel-Johnson plates?

phenol red

What indicates a positive result in a catalase test?

bubbling when bacteria and 5% H2O2 combine

What type of medium did we use to test for antibiotic resistance?

Meuller-Hinton agar

Which tube is positive for urease activity?

Test tube B

Why do urease tubes turn pink to indicate a positive result?

due to the formation of ammonia and phenol red

What results are indicated by tube D?

oxidative deamination (lactose fermentation), hydrogen sulfide production

What results are indicated by tube B?

acid production (glucose fermentation)

How is EMB selective?

It selects for eneterics by inhibiting organisms that cannot grow in the presence of bile salts

What results does this EMB plate indicate?

This organism ferments lactose to acidic end products

What does it indicate if there is growth of dark colonies on an EMB plate?

The organism ferments lactose, but not to acidic end products