Lab Quiz 3 Vocabulary Review

Vocabulary flashcards covering key laboratory topics including endospore staining, capsule staining, fluid thioglycollate broth, TSI agar, and SIM medium.

Endospore Stain Purpose

A differential staining technique used to differentiate bacteria that form endospores from non-spore-forming bacteria.

Endospore-producing Genera

The two best-known genera of endospore-producing bacteria: the anaerobic genus Clostridium and the aerobic genus Bacillus.

Malachite Green

The water-soluble primary stain used in endospore staining, which is applied after heat fixing $20\times$ and rinsed off after $20\text{ minutes}$.

Safranin (Endospore Stain)

The counterstain used in endospore staining to colorize vegetative cells, rinsed off after $1\text{ minute}$ before blotting dry.

Keratin

A protein component of the tough outer covering of endospores that provides resistance to adverse environmental conditions and standard staining procedures.

Sporulation

The process of forming a dormant, resting endospore from an active vegetative cell ($\text{Vegetative Cell} \rightarrow \text{Endospore}$).

Germination

The process where a resting endospore returns to an active vegetative cell ($\text{Endospore} \rightarrow \text{Vegetative Cell}$).

Endospore Locations

The three position classifications of an endospore within a mother cell: central (middle), terminal (end), and subterminal (between middle and end).

Capsule

A sticky, gel-like layer made of polysaccharides and/or polypeptides surrounding a cell that aids in adherence to surfaces and helps bacteria avoid phagocytosis as a virulence factor.

Capsule Stain Purpose

A differential staining procedure used to identify and distinguish capsule-producing organisms from non-capsule producers.

Fluid Thioglycollate Broth

A reducing growth medium containing sodium thioglycollate and cysteine used to test and determine the oxygen requirements of bacteria.

Resazurin

An indicator in Fluid Thioglycollate Broth that changes color based on oxygen presence, appearing pink where $O_2$ is present and white where $O_2$ is absent.

Obligate Aerobe

An organism that requires oxygen for growth and cannot survive or grow without $O_2$.

Obligate Anaerobe

An organism that cannot grow in the presence of oxygen and thrives in oxygen-free environments.

Facultative Anaerobe

An organism capable of growing with or without oxygen, but grows best when $O_2$ is present.

Aerotolerant Anaerobe

An organism that does not utilize oxygen for its metabolic processes but can tolerate and grow in the presence of $O_2$.

Microaerophile

An organism requiring a reduced, specific small amount of oxygen to grow.

Triple Sugar Iron (TSI) Agar

A differential medium used to identify Gram-negative rods based on glucose, lactose, and sucrose fermentation, sulfur reduction, gas production, and peptone catabolism.

Phenol Red (TSI)

A pH indicator in TSI agar that appears red under alkaline conditions (K) and yellow under acidic conditions (A).

SIM Medium

A combination differential medium used to test three bacterial characteristics: Sulfur reduction (S), Indole production (I), and Motility (M).

Cysteine Desulfurase

An endoenzyme that catalyzes the cleavage of cysteine into pyruvate, ammonia ($NH_3$), and hydrogen sulfide ($H_2S$) gas.

Thiosulfate Reductase

An endoenzyme that reduces sodium thiosulfate to produce hydrogen sulfide ($H_2S$) gas during anaerobic respiration.

Tryptophanase

An endoenzyme that hydrolyzes the amino acid tryptophan into indole, pyruvate, and ammonia ($NH_3$).

Kovacs Reagent

A chemical reagent added to SIM medium to test for indole production; a red top layer indicates a positive result.