1. Aseptically inoculate one
Trypticase Soy Broth tube, one Trypticase Soy Agar slant tube, one
Trypticase Soy Agar stab tube, and one Trypticase Soy Agar plate with B.
subtilis. (See
Fig. 11
)
Remember to label all tubes
with a wax marker. When streaking the agar plates, use either of the
patterns shown in Figure 4
or Figure 5. This procedure
is termed streaking for isolation and has a diluting effect. The
friction of the loop against the agar causes organisms to fall off the loop.
Near the end of the streaking pattern, individual organisms become separated
far enough apart on the agar surface to give rise to isolated single
colonies after incubation.
2. Aseptically inoculate one
Trypticase Soy Broth tube, one Trypticase Soy Agar slant tube, one
Trypticase Soy Agar stab tube, and one Trypticase Soy Agar plate with E.
coli. (See
Fig. 11)
3. Aseptically inoculate one
Trypticase Soy Broth tube, one Trypticase Soy Agar slant tube, one
Trypticase Soy Agar stab tube, and one Trypticase Soy Agar plate with M.
luteus. (See
Fig. 11)
4. Aseptically inoculate one
Trypticase Soy Broth tube, one Trypticase Soy Agar slant tube, one
Trypticase Soy Agar stab tube, and one Trypticase Soy Agar plate with M.
phlei. (See Fig.
11)
5. Incubate all the tubes and
plates inoculated with B. subtilis, E. coli, M. luteus,
and M. phlei at 37°C. Place the tubes in a plastic
beaker to keep them upright. Incubate the plates upside down (lid
on the bottom) to prevent condensing water from falling down on the growing
colonies and causing them to run together.
6. In order to illustrate that
microorganisms are all around us and to demonstrate the necessity for proper
aseptic technique, contaminate three Trypticase Soy Agar plates as
follows:
a. Remove the lid from the
first agar plate and place the exposed agar portion in or out of the
building for the duration of today's lab. Replace the lid, label the plate
"air",
and incubate it at room temperature. Do this plate first.
b. Using a wax marker, divide
a second petri plate in half. You and your partner both moisten a sterile
cotton swab in sterile water.
Rub
your swab over some surface in the building or on yourself. Use
this swab to inoculate your half of the second agar plate. Label the plate
and incubate at room temperature.
c. With a wax marker, divide
a third petri plate in half. Rub your fingers over the surface of your
half of the third agar plate. Label and incubate at 37°C.
Do this plate last
bravenet.com
