You've Just Isolated a New Bacterium in Pure Culture, and You

Multiple Choice

You've just isolated a new bacterium in pure culture, and you culture it on a general purpose medium where its cells have a coccobacillus morphology. When you examine the cells after culturing on a variety of differential media, you ?nd that in some cases, the cells appear a coccobacillus, but in others, they can be ?lamentous, cocci, or club-shaped. The best explanation for this observation is that _______.

A) the media were incubated at an incorrect temperature
B) the microscope is out of adjustment
C) the differential media are contaminated
D) the bacterium is pleomorphic
E) your culture has become contaminated