EXCERCISE 1 STUDYGUIDE

How should you label a petri dish?

-Always label the bottom of the plate (where medium is)

-Label around the edge of the plate for easier observation

-include on label:
◦ Your seat number
◦ Date
◦ Organism with which you are inoculating

How do we store petri dishes?

Inverted, bottom on top, because we don’t want condensation to ruin our plate/inoculation.

What temperature do we store out petri dishes?

37°C

What are the three types of media we will see?

◦ General purpose
◦ Selective
◦ Differential

What are the most common preparations of these broths will we see?

-Broth

◦ Agar slant 

◦ Agar deep tube
◦ Agar plate 

How do we handle test tubes?

-NEVER carry or pick up test tubes by the cap

-Test tubes should always be transported in a
test tube rack

-Test tubes are usually held in your non-
dominant hand

-Never put caps down on the benchtop

-Caps are removed using your dominant hand
and held throughout the transfer

Where and how do we label test tubes?

Label on clear portion with china marker. NOT ON CAP IT CAN BE REMOVED.

What is an inoculating loop used for?

Used to transfer culture and Must be sterilized before and after each transfer/incoluation

What is a micro incinerator used for?

Used for sterilization of inoculating
loops and test tube openings.

Plug in at the beginning of each lab and only touch the base of the incinerator as the barrel will be
very hot

How to use loop and micro incinerator together?

-Insert loop up to handle
-Do not rest against the inside of the
incinerator
-Allow ¾ of loop to glow red hot
-Remove and allow to cool

We use “aseptic technique” what does asepsis mean?

“without infection”

Using proper aseptic technique is essential for:

◦ Limiting the presence and spread of potentially harmful organisms
◦ Preventing exposure of yourself and others to potentially harmful bacteria
◦ Reducing the possibility of contaminating your samples

◦ A contaminated experiment is a

failed experiment, and a waste of your time and laboratory resources!

Ways to have aseptic techniques:

-Work in a clean environment: (Disinfecting our bench and washing our hands)

◦ Uncap samples only as long as it takes to perform the transfer or inoculation and Never lay down caps or tubes on benches

◦ Do not perform transfers, inoculations, smear preps, etc. over books or papers

◦ DO NOT TALK WHILE SAMPLES ARE OPEN!

-Be organized and have everything in arms reach to you when performing an experiment.

What is a two tube transfer?

Method in which aseptic technique is used to transfer a sample from a bacterial culture to another
uninoculated medium.

What should you do to your broth culture before transfer? And how?

Resuspend!

Hold tube loosely between two fingers and tap lightly with other hand to mix tube.

What are the Seven Steps of a two tube transfer?

1: Sterilize loop
2: Uncap Tubes
3: Sterilize Tubes
4: Transfer from culture to fresh medium
5. Sterilize tubes
6. Recap Tubes
7: Sterilize Loop

Broth cultures tend to what?

Sediment at bottom of tube.

Where do you grab caps when performing a two tube transfer?

Grab caps high to avoid touching opening with glove