BAA-390), which is also a BSL-1 microbe. Students record the
condition of their peeps, as many will be showing early symptoms of “necrotizing fasciitis” that accompanies the disease.
2. Students touch the surface of their moistened peep with an
inoculating loop and streak for isolated colonies on the following agar plates that are incubated at 37°C degrees:
• NA (nutrient agar)
• PEA (phenylethyl alcohol agar)
• MAC (MaConkey agar)
• EMB (Eosin Methylene Blue agar)
• MSA (Mannitol salt agar)
3. Place inoculated peeps into plastic Ziploc plastic bags and
incubate for 1 week at 30°C. Include one Ziploc bag with a
peep incubating only with NB as a control. (An alternative
approach is incubate peeps in containers of NB with bacteria.
Peeps left incubating with B. amyloliquefaciens will eventually
hydrolyze in NB at room temperature.)
Lab Period 2
1. Record growth patterns on agar plates (see Figure 1).
2. Expected results (colony sizes and appearance) are shown in
3. Pick an isolated colony for each bacterium to restreak on separate NA plates and incubate at 37°C for 1–2 days. (satisfies
4. Each student records the morphology of their peep inoculating in container with NB. (Have students compare appearances of their peeps and note if some are beginning to dissolve
more than others.)
Lab Period 3
1. Perform gram stains and spore stains on isolated bacteria
from lab period 2.
2. Use purified bacteria (step 3 from Lab 2) to “inoculate test
animals.” This means using sterile swabs to inoculate tubes
containing 3–5 ml NB and a gummy bear submerged in the
NB. Include a tube with NB and a gummy bear but without
bacteria as a control. Incubate at 30°C until lab period 3.
(satisfies postulate 3)
3. Record which of the peeps in the original Ziploc bags (step 4
from Lab 2) show signs of “peep pox” (have visible signs of
hydrolysis compared to the control).
4. As a class share observations on peeps:
• Physical appearances of their peeps.
• Whether or not their peep contained bacteria that produce
large, mucoid colonies on PEA and large colonies without
yellow halos on MSA. (satisfies postulate 1)
Lab Period 4
1. Place gummy bear inoculations at 4°C for 15–30 min before
determining if gummy bear shows signs of “peep pox”
(hydrolysis). (satisfies postulate 3)
2. Use liquid from gummy bear tube to streak for isolated colonies on PEA or MSA plates. (satisfies postulate 4)
3. B. amyloliquefaciens should be identified as the etiological
agent of “peep pox.” Reveal to the students the identities of
the two other test bacteria used in the exercise, and have them
generate a dichotomous key for identification of all three
Figure 1. Time lapse photography of a peep showing symptoms of peep pox. Incubation times from left to right are 0, 2, 4, and
Table 1. Expected colonly size and appearance.
bacterium NA PEA MAC EMB MSA
E. coli medium small dark pink metallic green no growth
S. aureus small medium no growth no growth small, yellow hallo
B. amylo. large large, mucoid no growth no growth large, no yellow halo
Note: Images of expected results are available in the online supplementary material.