Information for High School Student Microbiology Projects:
Growing bacteria..
Following is some limited information about how to
culture and grow bacteria on agar media This
is far from complete and is intended to provide only very basic information.
Many microbiology laboratory manuals go into detail. Ask your science
teacher, check with your library or surf the Internet for detailed
information.
Strict
safety precautions should be followed when growing bacteria, whether a known strain
or unidentified species from environmental sources. Pure cultures of otherwise
" harmless bacteria" can become contaminated with potential
pathogens (disease causing!). Likewise, bacteria cultured from the skin,
mouth, sinks or dirt can be potentially dangerous if they get into cuts or
contact with mucous membranes, including the eyes, mouth, nose or ears..
Always wear latex gloves and protective clothing such as a lab coat and safety
goggles when handling your cultures and be certain to properly dispose of your
experiments when finished.
We encourage you to discuss projects involving the growth of
bacteria with your science teacher to make certain appropriate facilities for
the growth and handling of microorganisms are made available to you.
To grow bacteria you need to
supply them with nutrients (a food source). In the particular case of blood
agar the bacteria are getting the majority of their nutrients from the blood
(could be sheep' blood), other nutrients which are necessary for growth may be
added to the agar. The
bacteria do not use the agar for growth, in fact the agar merely provides a
semi-solid surface to grow the bacteria on.
As for temperature, if you are
growing bacteria on blood agar plates it usually implies that you are trying
to culture bacteria which live in an animal. Therefore you would want to
incubate the plates at the same body temperature of
the animal. For
example, take a sterile cotton swab and swab the inside of your cheek and then
use this swab to streak a blood agar plate. Since our body temperature is
usually 98.6’F (37 C) you would
want to incubate the blood agar plate at 37 Celsius as the bacteria are
accustomed to this temperature.
