Problem:

What would make a mixed culture of 2 organisms appear pure on a streak plate? (You expect to see two colony morphologies but only see one.)

Select one or more:

a. Organisms that are different genetically can have the same colony morphology.

b. The plate was not incubated in favorable temperature conditions for both organisms.

c. The plate was not incubated for very long and the two organisms have different growth rates.

d. You did not flame the loop properly between quadrants but otherwise performed aseptic technique perfectly.

e. You autoclaved the broth prior to making the steak plate. f. A contaminant of different colony morphology got onto the plate.

Please suggest correct answer.