Microbiology Lecture Review - Flashcards

Vocabulary flashcards generated from lecture notes on extracellular enzymes, amino acid targeting enzyme tests, coliform detection labs, fermentation, staining techniques, and other biochemical tests. These flashcards are designed to help review key concepts and prepare for the exam.

DNase Test

Tests for DNase enzyme that breaks down DNA into nucleotides, uses methyl green dye as an indicator, and a positive result is a clear halo around growth.

Starch Test

Tests for amylase enzyme that breaks down starch, uses iodine as an indicator, and a positive result is a clear halo.

Gelatin Test

Tests for gelatinase enzyme that breaks down gelatin, with a positive result indicated by liquefaction (gelatin remains liquid after refrigeration).

Urease Test

Tests for urease enzyme that breaks down urea, uses phenol red as an indicator, and a positive result is a hot pink color.

Phenylalanine Deaminase Test

Tests for deaminase enzyme that removes the amino group from phenylalanine, uses ferric chloride as a reagent, and a positive result is a green color.

Lysine Decarboxylase Test

Tests for enzyme that removes the carboxyl group from lysine under anaerobic conditions, uses bromocresol purple as an indicator, and a positive result is purple.

Lysine Iron Agar (LIA) Slant

Combines tests for lysine decarboxylase and lysine deaminase, using bromocresol purple and iron salts as indicators, with results indicated by purple butt (decarboxylation) and rusty red slant (deamination).

MacConkey Agar

Selective for Gram-negative bacteria and differential for lactose fermentation. Positive for coliforms indicated by pink/red colonies.

EMB Plate (Eosin Methylene Blue)

Selective for Gram-negative bacteria and differential for lactose/sucrose fermentation. Positive for coliforms indicated by dark colonies or a green metallic sheen (E. coli).

BGLB (Brilliant Green Lactose Bile Broth)

Contains brilliant green, lactose, and bile. A positive result (coliform present) is indicated by turbid broth with a gas bubble.

Hektoen Enteric (HE)

Selective for non-coliforms, contains bile salts, lactose, and extra sugars. Orange/yellow colonies indicate lactose fermentation (coliforms, negative test), and green colonies (with/without black centers) indicate non-lactose fermenters.

Phenol Red Broths

Uses phenol red as an indicator; turns yellow if acid is produced (positive fermentation). Hot pink indicates alkaline conditions (negative result).

Mannitol Salt Agar (MSA)

Selective for Staphylococcus spp. and differential for mannitol fermentation, which turns phenol red yellow.

OF Glucose Test

Tests for oxidation vs fermentation using bromothymol blue as an indicator. Yellow/orange color indicates acid production; both tubes yellow indicates facultative anaerobe.

Citrate Test

Tests for citrate permease enzyme on Simmon’s citrate agar. A positive result (citrate used) is indicated by a blue color.

Gram Stain

Used to identify Gram-positive (purple) vs Gram-negative (pink) bacteria.

Negative Stain

Uses negatively charged dye to stain the background rather than the cells.

Indole Test (SIM Media)

Tests for tryptophanase enzyme and indole production. A positive result is a cherry red layer on top after adding reagent.

Methyl Red (MR)

Tests for mixed acid fermentation, with a positive result indicated by a red color.

Voges-Proskauer (VP)

Tests for 2,3-butanediol fermentation (neutral products), with a positive result indicated by a red color after adding reagents.

H₂S Production

Black coloration in media due to production of Hydrogen Sulfide gas, indicating sulfur metabolism.