Microbiology lab practical

50 terms by lmb6871 

Create a new folder

Advertisement Upgrade to remove ads

microbial culture

One of the diagnostic methods of microbiology and it is used to determine the cause of an infectous disease by allowing the microorganism to multiply in certain specific media under controlled lab conditions.

medium

contains nutrients for growth of microbes.

Colony

visible mass of microorganisms growing on a solid medium; in general it is formed from reproduction of a single cell so that all the members of a colony are desendant from that original cell

mixed culture

two or more kinds of microbial species are found

pure culture

one kind of microbial species is found

stock culture

a culture of a microorganism maintained solely for the purpose of keeping the organism in a viable condition by subculture into fresh medium

selective medium

allows the growth of certain kinds of bacteria while inhibiting the growth of others

differential medium

allows you to differentiate microbes based on thier metabolic activity

Types of differential Mediums

Blood Agar, gelatin, SIM Tubes, Simmons Citrate

Types of Selective Medium

Sabouraud Dextrose

Both Selective & Differential Medium

Kligler Iron Agar, Mac Conkey Agar, Mannitol Salt Agar

Neither Selective nor Differential

Mueller-Hinton Agar, Nutrient Agar

total Magnification

determined by multiplying the eye piece power (usually 10x) by the objective lens in place. EX. a 10x eyepiece and a 4x objective yields a total magnification of 40x

working distance

distance between the objective lens and the specimen. At low mag the working distance is longer

par-focal/par-centered

specimens that appear in focus or centered in the field of view at one magnification level will also appear centered when mag level is changed

turbidity

cloudiness of broth

flocculent

cottony or wooly masses floating in broth

pellicle

"skin" that forms on the surface of a broth culture

primary stain

Stains what you want to see;crystal violet

mordant

sets dye; fixes crystal violet to cell wall;iodine

counterstain

makes cells or structures more visible;safranin

Why is a dilution series often done before making colony counts?

By diluting it becomes easier to identify viabile colonies when using streak plate method.
Determining # of organisms in original culture
# if colonies x plating dilution factor x tube dilution factor

What is meant by "Zone of Inhibition"?

The area on an agar plate where growth of a control organism is prevented by an antibitic, usually placed on the agar surface. If the organism is suseptible to the abntibiotic there will not be growth where the anitibiotic is.

For what reasons might a chemical that is usually thought to be a good antimicrobial show no zone of inhibition?

• They have acquired antibiotic resistance
• The antibiotic disk isn't carefully pressed down enough into agar plate before being inverted and incubated

Why is it important for many of the media used this semester to set up a negative control tube?

For the comparison to see exactly what and how much growth.

How would you test for the ability of a microbe to produce catalase?

Use loop to transfer some growth from bacteria to a clean microscope slide. Use sterile dropper to apply several drops of hydrogen peroxide to bacteria. Bubbling indicates the release of oxygen gas and a positive reaction for the enzyme catalase

What medium is used to test for hemolysis?

Blood Agar
Hemolysis destroys red blood cells

What chemical is added to starch plates to test for reaction?

Iodine

What is enzyme that breaks down starch?

Amylase

Gram positive

Purple

Gram Negative

Red

Basic Shape of bacteria

coocus, rod(bacillus), and spiral

Basic Shape of Endospore

spherical

Basic Shape of Algea on wet mount

chains

Basic Shape of Aspergillus

dandellion

Basic Shape of Penicillium

skeleton fingers

Basic Shape of Rhizopus

Tootsie Pop

Basic Shape of Plasmosium

circle, crescent, sausage shaped

Basic Shape of Trypanosoma

C-shaped

Basic Shape of Balantidium

Oval (kind of flask shaped)

Process used to grow lytic phages

Pour mixture of bacterial stock, viral dilution, and soft agar over agar plate. These mixtures solidify and are then incubated.

Voges-Proskauer Test

Mixes with reagants A & B after 4 days. After adding the reagants look closely for color change which indicates acetoin production.

Heat fix

Pass slide through flame 3 times.

obligate aerobes

Must have oxygen in order to breakdown organic molecules for energy

Fermentation

Microbes that can produce energy through both anaerobic and aerobic . Organisms remove electrons from organic fuels and pass these electrons to other organic compounds. Final product often includes some type of acid and gas.

Faculative anaerobes

Can survive with or without oxygen

Obligate anaerobes

Can only produce energy anaerobically and oxygen is toxic

What do you use to test for motility?

SIM tube (Sulfide, Indole, Motility)

Fimbriae

hair like structures that allow bacterial cells to attach to each other.

What are Durham tubes used for?

To test for the ability of microbes to ferment a variety of different carbohydrates.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set