Using cultures to study and identify bacteria has been monumental, as it has given scientists a way to study bacteria independent of their environment. Using methods like the Quadrant Streak Method for Isolation on agar plates allows students and scientists to isolate bacteria and study their physiology and morphology. Another reason using cultures to identify bacteria is important is because it has created a large database of material, which can be used to study newly discovered organisms. Because cultures allow scientists to store isolated bacterium and study them chronically, much is known about the small amount of bacteria that is able to be grown in the lab. .
This study will use a mixture of two of these well-studied bacterial species to provide an opportunity to learn how to isolate them from one another and how to use differential testing to find their identity. Unknown 9 was used for this experiment. The hypothesis for this experiment is that the bacteria will be from different families or genera, which will make isolating them fairly straightforward. Further, there will be specific differential tests that will be able to be used once the genus of the bacteria is identified. .
Methods.
The first step in identifying Unknown 9, comprised of two unknown bacteria, was to do a quadrant streak plate for isolation. To prepare the streak plate warm ENA and NA were poured into pre-labeled empty plates. These plates were allowed to cool and solidify before their use. An inoculation loop was sterilized using a Bunsen burner, heating the loop until it was red-hot. The loop was then allowed to cool to room temperature and was then dipped into Unknown 9 to retrieve a loop-full of broth. On a cool and solidified plate (either ENA or NA), one sector of the plate was heavily streaked with Unknown 9, making sure to stay close to the edge of the plate. The inoculation loop was then re-sterilized and allowed to cool to room temperature.
