Microbio Lab Quiz #1

Lab 1 Content

Microbe

Living organisms that require a microscope in order to be seen

• Can be single-celled or multicellular

• Ex: bacteria, fungi, yeast, archaea

Noncellular microbes

Non-living microbes that cannot reproduce without a host (ex: viruses)

Tryptic soy agar (TSA)

Artificial general growth medium that provides adequate nutrient and growth conditions for microbes

General growth medium

Permits the growth of a wide variety of culturable microbes

Culturable microbes

Any microorgranism, like bacteria, yeasts, and fungi, that are able to grow on artificial growth media

Tryptic soy agar (TSA) vs. tryptic soy broth (TSB)

Contains same nutritional make-up

Carbon source = tryptone energy source = glucose

• TSA: contains agar (solidifying agent) → solid at room temperature

• TSB: contains NO agar → liquid at room temperature

Microbes are…

ubiquitous (in every imaginable environment, microbes can be found)

Aseptic technique

An umbrella term used to describe ALL techniques and procedures that aid in preventing contamination of materials and microbial culture

• Ex: wiping table with lysol, washing hands/wearing gloves, working under bunsen burner flame, etc.

Sterilization vs. disinfection

• Sterilization: process that kills, removes, or deactivates ALL microorganisms

  • Ex: autoclaving, flame sterilization

• Disinfection: the removal and killing of some microbes from a surface/material, but does not necessarily remove everything

  • Ex: lysol, washing hands

Subculture

The act of purposefully transferring bacteria from one growth medium to another

Inoculate

To purposefully introduce or “give” bacteria to a previously sterile environment or medium

Pure colony/culture

A single strain of a species of bacteria; genetically identical twins

• Cells that are on its own, not touching any other microbial colonies

Dilution

When streaking on a solid medium, and you want to obtain well-separated colonies

Chromogenic vs. nonchromogenic

• Chromogenic: some organisms that produce pigments that color the colony/medium upon which it grows

• Nonchromogenic: MOST organisms appear a shade of white, gray, or tan

Mannitol salt agar (MSA)

Selective and differential growth medium → high salt concentration (7.5% NaCl)

• Allows us to know more specific information about the organism plated

  • Has ingredients that provides further characterization in comparison with a general growth medium

Selective function

Only certain organisms can grow on the agar

• Facilitates growth of those organisms and inhibits others

Differential function

Selective organisms that do grow on this plate will be selected into different classification groups

• Separated into groups based on visible color change

Halophiles

Salt-loving organism that can grow at a higher salt concentration

• Can grow on MSA mediums

Carbohydrate mannitol

A sugar that organisms can use during fermentation

Phenol red

Used to produce a visual color change when the pH changes

When fermentation occurs…

the pH changes and results in an acidic product

• pH of 7.5-8: red color (slightly basic but close to neutral)

• pH below 6.6: yellow color (more acidic)

  • Means organism ferments mannitol → color change