Lab Practicum: Tests

Lactose fermentation broth

pH indicator: Phenol Red

Tests for: Lactose fermentation

Positive result: Yellow broth, maybe gas

Negative Result: Red broth

Glucose fermentation

pH indicator: Phenol Red

Tests for: Glucose fermentation

Positive result: Yellow broth, maybe gas

Negative Result: Red broth

Sucrose fermentation

pH indicator: Phenol Red

Tests for: Sucrose fermentation

Positive result: Yellow broth, maybe gas

Negative Result: Red broth

MR

Methyl Red reagent

Tests for: Mixed-acid fermentation

Positive result: Red after reagent

Negative result: Yellow

VP

Barritt's A & B

Tests for: Acetoin production

Positive result: Red after reagent

Negative result: Brown

Citrate

pH indicator: Bromothymol Blue

Tests for: Citrate utilization

Positive result: Growth and blue medium

Negative result: No growth; green medium

Urea Agar Slant

pH indicator: Phenol Red

Tests for: Urease production

Positive result: Bright Pink

Negative result: Orange

Tryptone broth (Indole)

Kovac's Reagent

Tests for: Metabolize tryptophan and generate Indole as a byproductc

Positive result: Red ring on top after Kovac's

Negative result: Yellow/no red ring

Hydrogen Sulfide (H₂S)

Tests for: Ability to reduce sulfur-containing compounds to hydrogen sulfide gas (H₂S)

Positive result: Black precipitate

Negative result: No blackening

PAD Slant

Ferric Chloride Reagent

Tests for: Phenylalanine deaminase

Positive result: Green

Negative result: No green

Catalase

Hydrogen Peroxide reagent

Tests for: Catalase enzyme

Positive result: Bubbles

Negative result: No bubbles

Oxidase

TMPD Oxidase reagent

Tests for: Oxidase

Positive result: Purple/blue

Negative result: No color

KIA Slant

pH indicator: Phenol Red

Tests for: Glucose/lactose fermentation, gas, H₂S

Positive result: Yellow butt/slant depending on fermentation

Negative result: Red slant and/or butt

SIM Deep

Kovac's Reagent

Tests for: Sulfur reduction, indole, motility

Positive result: Red ring (indole), black precipitate (H₂S), diffuse growth (motility)

Negative result: No red ring, no blackening, growth on stab line

Coagulase

Rabbit plasma reagent

Tests for: Coagulase enzyme

Positive result: Clumping or clot formation

Negative result: No clumping/clot

Blood agar

Hemolysis

Type	Appearance
Alpha	Green partial clearing
Beta	Complete clearing
Gamma	No clearing