Culture Media and Pure Culture Techniques

This set of vocabulary flashcards covers concepts from the culture media and pure culture techniques lecture, including physical states, chemical compositions, functional types of media, and inoculation methods.

Culture Medium

An aqueous solution of various nutrients suitable for the growth of microorganisms.

Culture

A particular strain or kind of organism growing in a laboratory medium.

Pure Culture

A culture containing a single kind of microorganism.

Liquid Media

Water-based solution without a solidifying agent, such as broths, milk, and infusions.

Semisolid Media

Media with a clotlike consistency at ordinary room temperature; contains a small amount of solidifying agent ($agar$ or $gelatin$) but does not form a firm substance.

Solid Media

Media with a firm surface using solidifying agents such as $agar$, $gelatin$, or $silica\,gel$.

Agar-agar

A solidifying agent made from seaweed extract.

Gelatin

A protein obtained by boiling skin, tendons, ligaments, and/or bones with water; usually obtained from cows or pigs.

Synthetic or Defined Media

Media whose compositions are chemically-defined, composed of organic and inorganic compounds with molecular contents specified by means of an exact formula.

Non-synthetic or Complex Media

Media with ingredients that are not chemically-defined, not simple or pure compounds, and with no exact chemical formula.

General Purpose Media

Media designed to support the growth of many microorganisms.

Selective Media

Media that suppress unwanted microbes and encourage desired microbes.

Differential Media

Media used to distinguish colonies of desired microbes from others.

Enrichment Media

Liquid media that are selective but increase the number of desired microbes to detectable levels by inhibiting unwanted commensal or contaminating bacteria.

Enriched Media

Solid media containing extra nutrients in the form of egg yolk, blood, or serum to facilitate the growth of fastidious microorganisms.

Reducing Media

Media used to grow obligate anaerobes.

Eosin Methylene Blue (EMB) Agar

A selective and differential medium used to isolate fecal coliforms where aniline dyes inhibit $G+$ organisms.

MacConkey Agar

A selective and differential medium designed to isolate and differentiate enterics; bile salts and crystal violet inhibit $G+$ organisms.

Mannitol Salt Agar

Selective for Gram + bacterium staphylococci due to a high concentration ($7.5\%-10\%$) of $NaCl$.

Blood Agar

Enriched media consisting of $5\%$ sheep blood used to identify hemolysis patterns (Beta, Alpha, and Gamma).

Chocolate Agar

Media enriched with heat-treated blood ($40-45^{\circ}C$) for growing fastidious respiratory bacteria needing growth factors $V$ ($NAD$) and $X$ ($hemin$).

Thayer-Martin (VPN) Agar

A medium containing vancomycin, polymyxin, and nystatin used to test for Neisseria gonorrhoeae.

Selenite F Broth

An enrichment medium that favors the growth of Salmonella and prevents the growth of normal competitors like E. coli.

Thioglycollate Broth

A reducing medium used to test the aerotolerance of bacteria; contains sodium thioglycollate, thioglycollic acid, or $L-cysteine$ to react with molecular oxygen.

Resazurin

A redox potential indicator used in reducing media that turns pink in an oxidized environment.

Contaminants

Unwanted microorganisms.

Streak Plate Technique

A plating technique used to obtain a pure culture by spreading a loopful of organisms over the surface of a solid medium in patterns like Quadrant, Radiant, or Continuous.

Spread Plate Technique

A technique where a bacterial dilution is spread evenly over the surface of a solid medium using a hockey stick or L-shaped rod.

Pour Plate Technique

A technique where a bacterial sample is mixed with warm agar and poured into a plate, resulting in colonies growing both in and on the medium.

Bacterial Colony Morphology

The classification of colonies based on Form (e.g., Circular, Rhizoid), Elevation (e.g., Convex, Umbonate), and Margin (e.g., Entire, Undulate).