Microbiology Lecture Review

Vocabulary flashcards covering key concepts from microbiology lecture notes.

Oxygen tests

Uses oxygen as energy source; tested in unsealed tubes. Testing for aerobic respiration

Fermentation

Occurs in sealed tubes with mineral oil to remove oxygen.

Alpha Hemolysis

Bacterial cells damage RBCs, hemoglobin turns into methemoglobin; plate appears brownish.

Beta Hemolysis

Bacterial cells damage RBCs; clearing around growth.

Mannitol Salt Agar (Selective)

Selective due to 5% NaCl content.

Mannitol Salt Agar (Differential)

Differential because mannitol fermentation releases acid end products, turning the plate yellow (acidic pH).

DNase Test Positive Result

Clearing around growth; DNA is degraded, methyl green cannot bind.

Bile Esculin Slant Positive Result

Appears all black due to esculin hydrolysis into esculetin, which releases sulfide that binds to iron.

Durham Tube Bubbles

Indicates presence of non-soluble molecules such as O2, H2, or N2.

Nitrate Reduction Test Positive Result (After Reagents)

Red color after adding reagents indicates nitrate was reduced. POS

Nitrate Reduction Test Positive Result (After Zinc Dust)

Turns red signifies nitrate was reduced by zinc dust, not bacteria. NEG

Citrate Slant Positive Result

Media turns blue due to increased pH (more basic) from citric acid removal.

Methyl Red Test

Tests for mixed acid fermentation. Positive turns red

Voges-Proskauer Test

Tests for 2,3-butanediol fermentation. Positive turns brown to red (Acetoin is present)

Amylase

Breaks down starch into glucose.

Starch Agar Test

Tests for the presence of amylase.

Caseinase

Degrades casein (milk protein) into individual amino acids.

Casein Hydrolysis Test

Tests for the presence of caseinase.

Lipase

Degrades fats (triglycerides) into glycerol and fatty acids.

Lipid Hydrolysis Test

Tests for exoenzyme lipase, using spirit blue agar (dark blue line if positive).

Urease

Breaks down urea into 2 ammonia molecules and CO2.

Urea Broth Test

Tests for the presence of urease (fuschia color at alkaline pH).

Triple Sugar Iron (TSI) Agar

Tests for sugar fermentation and sulfide production from thiosulfate reduction.

Sulfide Indole Motility (SIM) Test

Tests for sulfide production, indole production from tryptophan, and motility.

Tryptophanase

Enzyme tested for in the SIM test that breaks down tryptophan into indole.

Phenylalanine Deaminase

Enzyme tested in Phenylalanine slant test.

Eosin Methylene Blue Agar (EMB)

Tests for lactose and sucrose fermentation. Selective agents: Eosin Y and Methylene blue.

MacConkey Agar (MAC)

Tests for lactose fermentation. Selective reagents: Bile salts and Crystal violet.

Salmonella-Shigella Agar (SS)

Tests for lactose fermentation, Black colonies indicate that sulfareses are present in the media