Micro Lab Final

What stains are used in a Gram stain?

Crystal violet, safranin

What is a Gram stain used to detect?

Whether bacteria are Gram-positive (+) or Gram-negative (-)

What is a positive Gram stain result?

Purple cells

What is a negative Gram stain result?

Pink cells

What stains are used in an Endospore stain?

Malachite green and safranin

What does an Endospore stain detect?

Presence of endospores

What is a positive Endospore stain result?

Green endospores inside reddish/pink vegetative cells

What is a negative Endospore stain result?

Solid reddish/pink cells with no green endospores

What stains are used in a Capsule stain?

Congo red and Maneval's stain

What does a Capsule stain detect?

Ability to produce an extracellular capsule

What is a positive Capsule stain result?

Dark-stained cell with a clear/white halo (capsule) around it on a light background

What is a negative Capsule stain result?

No white halo around the cell

What stains are used in an Acid-Fast stain?

Carbolfuchsin, methylene blue, and acid-alcohol decolorizer

What does an Acid-Fast stain detect?

Presence of mycolic acid in the bacterial cell wall

What is a positive Acid-Fast stain result?

Reddish-purple cells

What is a negative Acid-Fast stain result?

Blue cells

What stains are used in a Simple stain?

Crystal violet, safranin, or methylene blue

What is a Simple stain used to detect?

Bacterial morphology, size, and arrangement

What is a positive result for a Simple stain?

Cells are clearly stained (not colorless)

What is the appearance of cells in a negative Simple stain result?

Cells are unstained/colorless

What stain is used in a Hanging Drop preparation?

No stain

What is a Hanging Drop preparation used to detect?

Bacterial motility

What is a positive Hanging Drop result?

Movement of bacteria

What is a negative Hanging Drop result?

No movement of bacteri

What test is carbol fuchion used for?

Acid-fast stain

What test is malachite green used for?

spore stain

What test is the reagent Covac’s Solution used for?

indole production

What is the name of the media that tests for hydrogen sulfide prodcution?

kligler’s iron agar

What is the name of the media used to test anaerobic fermentation?

O-F media

What reagent was added to the starch plate to see if it was hydrolyzed?

iodine

Every sample was heat fixed

false - not capsule stain

What media was used for mixed acid fermentation?

MR-VP broth

What was the counterstain used in the capsule stain?

maneval’s

what is the decolorizing agent used in the gram stain?

95% ethanol

What is the counterstain used in the spore stain?

safranin

What is the counterstain used in the acid-fast stain?

methylene blue

Catalase test reagent

hydrogen perioxide

mixed acid fermentation reagent

methyl red

indole test reagent

kovac’s reagent

oxidase test reagent

oxidase reagent

starch hydrolysis reagent

iodine

What is ELISA and what is it used for?

ELISA is a laboratory test that detects and measures specific proteins, antigens, antibodies, and hormones in biological fluids. It is used to determine pregnancy, diagnose disease, and measure immune responses.

What media is used for the Oxidation-Fermentation (O-F) test?

Hugh and Leifson's O-F medium

What does the Oxidation-Fermentation (O-F) test detect?

Differentiates bacteria based on their ability to oxidize or ferment specific sugars

What reagent is added in the Oxidation-Fermentation (O-F) test?

Mineral oil is added to one tube

What is a positive Oxidation-Fermentation (O-F) test result?

Yellow medium

What is a negative Oxidation-Fermentation (O-F) test result?

Green medium

What media is used for the Phenol Red Fermentation test?

Phenol red glucose broth

What does the Phenol Red Fermentation test detect?

Differentiates Enterobacteriaceae based on their ability to ferment specific carbohydrates

What reagent is added in the Phenol Red Fermentation test?

Durham tube

What is a positive Phenol Red Fermentation test result?

Yellow broth; gas production may produce bubbles in the Durham tube

What is a negative Phenol Red Fermentation test result?

Red or pink broth

What media is used for the Methyl Red (MR) test?

MR-VP broth

What does the Methyl Red (MR) test detect?

Production of mixed acids from glucose fermentation

What reagent is added in the Methyl Red (MR) test?

Methyl red indicator

What is a positive Methyl Red (MR) test result?

Red

What is a negative Methyl Red (MR) test result?

Yellow (no color change)

What media is used for the Voges-Proskauer (VP) test?

MR-VP broth

What does the Voges-Proskauer (VP) test detect?

Production of acetoin (2,3-butanediol fermentation)

What reagents are added in the Voges-Proskauer (VP) test?

α-Naphthol, potassium hydroxide (KOH), and distilled water

What is a positive Voges-Proskauer (VP) test result?

Red

What is a negative Voges-Proskauer (VP) test result?

Yellow (no color change)

What media is used for the Catalase test?

A bacterial colony on a microscope slide

What does the Catalase test detect?

Presence of the enzyme catalase

What reagent is added in the Catalase test?

3% hydrogen peroxide (H₂O₂)

What is a positive Catalase test result?

Bubbles form immediately

What is a negative Catalase test result?

No bubble

Oxidase – Media

oxidase disk or oxidase paper

Oxidase – Testing For

detects if the organism produces the enzyme oxidase

Oxidase – Reagent

oxidase reagent

Oxidase – Positive Result

dark blue/purple within 20 seconds

Oxidase – Negative Result

no color change

Nitrate – Media

nitrate broth

Nitrate – Testing For

ability to reduce nitrate to nitrite

Nitrate – Reagents

sulfanilic acid, α‑naphthylamine, zinc dust

Nitrate – Positive Result

gas production or red color after reagents

Nitrate – Negative Result

red color after zinc dust

Citrate – Media

Simmons citrate agar

Citrate – Testing For

ability to use citrate as sole carbon source

-Citrate – Reagent

none

-Citrate – Positive Result

blue color change or growth

Citrate – Negative Result

no change

Starch – Media

starch agar plate

Starch – Testing For

amylase production

Starch – Reagent

Gram iodine

Starch – Positive Result

clearing around growth

Starch – Negative Result

no clearing

Casein – Media

milk agar plate

Casein – Testing For

casease production

Casein – Reagent

none

Casein – Positive Result

clearing in agar around organism

Casein – Negative Result

no clearing

Gelatin – Media

nutrient gelatin

Gelatin – Testing For

gelatinase production

Gelatin – Reagent

none

Gelatin – Positive Result

gelatin becomes liquid

Gelatin – Negative Result

gelatin remains solid

Urea – Media

urea broth

Urea – Testing For

urease production

Urea – Reagent

none