Question: Aseptic Technique

Answer: Insures that no contaminating organisms are introduced into culture materials when the latter are inoculated or handled in some manner,

Insures that organisms that are being handled do not contaminate the handler or others.

No contamination remains after you have worked with cultures.

Question: Work Area Disinfection

Answer: Treated with a disinfectant to kill any microorganisms that may be present

Destroys vegetative cells and viruses, but may not destroy endospores

Question: Loops & Needles

Answer: Transfer of cultures is done by using inoculating loops & needles.

Implements must be sterilized before transferring any culture.

Sterilized by by putting it into a bunsen burner until it is red hot. But allow loop to cool before picking up inoculum. Ensures viable cells are transferred.

Question: Culture Tube Flaming and Inoculation

Answer: Prior to inserting a cooled loop or needle into a culture tube, the cap is removed and the mouth of the tube may be flamed.

Question: Petri Plate Inoculations

Answer: Loops are used to inoculate or streak petri plates.

Plate cover is raised and held diagonally over the plate to protect the surface from any contamination in the air.

The loop containing the inoculum is then streaked gently over the surface of the agar.

Cover replaced and loop is flamed

Question: Final Flaming of the Loop or Needle

Answer: After inoculation is complete, loop or needle is flamed to destroy any organisms. Should never be placed on the desk surface.

Question: 2 examples of how heat is used during inoculation of a tube culture

Answer: The flame from a Bunsen burner is used to sterilize transfer instruments (e.g. inoculating loop) and is used to flame the opening of the tube after the cap is removed and before the cap is replaced.

Question: How is air contamination prevented when an inoculating loop is used to introduce or take a bacterial sample to/from an agar plate?

Answer: Since the opening of a plate is not readily flamed, one should hold the lid over the top of the open plate when inoculating so that air contamination is limited. Working near a flame is also useful.

Question: How should agar plates be incubated? Why?

Answer: Agar plates should be incubated in an inverted position to prevent condensation on the agar surface that could spread the inoculated organisms.

Question: Against which organisms are disinfectants effective? Against which type of organism may they not be effective? What disinfectant is used in our lab?

Answer: Disinfectants, such as bleach and alcohol, are generally useful against vegetative cells and viruses but may not completely eradicate bacterial endospores.