Significant advances in agriculture, medicine, and food science have been made through the study of this area of microbiology

4. To acquire the skill of aseptic technique in the field of Microbiology.

2. To prevent contamination of cultures and media from microbes in the environment.

3. To transfer cultures from one medium by inoculating another medium. This is called subculturing
Discussion/Aseptic Techniques/Culturing Microbes

Significant advances in agriculture, medicine, and food science have been made through the study of
this area of microbiology. To study microorganisms, they must be increased in number through growth.
To grow microorganisms, we must have a method of transferring the organism to a sterile growth
medium (a liquid/broth or gel/agarisolid designed to support the growth of microorganisms) without
introducing any unwanted, outside contaminants. This method of preventing unwanted microorganisms
from gaining access is termed aseptic technique.

Aseptic technique is a fundamental and important laboratory skill in the field of microbiology.
Microbiologists use aseptic technique for a variety of procedures (such as transferring microbiology
cultures, inoculating media, isolation of pure cultures, and for performing microbiological tests). Proper
aseptic technique prevents contamination of cultures from foreign bacteria that are always present in
the environment.

To culture or grow microorganisms we must have a sterile, nutrient-containing medium in which to
grow the organisms. Anything in or on which we grow microorganisms is termed a medium.

Activity 1: Watch “Aseptic Technique” video noting the aseptic techniques used to transfer bacteria

to various growth media

~*Significance of Flaming as an Aseptic Technique***

Flaming the loop: Holding the loop in the flame of the Bunsen burner kills all contaminating organisms,
thus sterilizing the loop. The loop should glow red-not for a few seconds. After flaming, make sure to
slightly cool the loop before picking up organisms from the inoculum culture (the culture that is to be
transferred.) When transferring a culture from a plate, cool the loop by touching on the very edge of
agar. When transferring from a broth, the red-hot loop will make a sizzling noise as soon as you insert it
into the culture. The loop will automatically cool once it makes contact with the broth culture but wait a
one or two seconds before removing the loopful of inoculum from the tube. (The hot loop may create
aerosols when it touches the media containing microorganisms. It will cause some of the broth and
bacteria to boil briefly, creating a bacteria-containing aerosol. These airborne bacteria have the chances
of entering the respiratory tract or into the body parts. If you hear a hissing sound when you place the
heat sterilized loop into the broth culture indicates that the loop is not cooled sufficiently).