microorganisms was practiced in the third part of the lab. Practicing isolating an unknown microorganism on a culture media exposes the student to the first step in identifying an unknown microorganism from a certain environment. The results were not what the students expected. There was little growth on both the MacConkey and sodium azide plates. The sodium azide
plates only seemed to grow colonies of the Staphylococcus aureus and a small amount of the Enterococcus faecalis. E. coli and P. aeruginosa did not grow on the sodium azide plate because they are both gram negative bacteria and the sodium azide plate prevents growth of gram negative bacteria. The little growth of E. faecalis on the sodium azide plate could have resulted from poor inoculation of bacteria on the media. The MacConkey plate grew colonies of the Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa. Staphylococcus aureus did not grow on the MacConkey plate because this plate prevents growth of gram-positive bacteria. Errors that could have occurred in this lab were poor aseptic techniques that led to an unsterile environment. Poorly executed inoculation of the microorganisms could have lead to little or zero growth on the bacteria. Another possible error in inoculation and growth of microorganisms could have been not allowing the inoculating loop to cool after sterilization killing the bacteria before incubation.
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