Isolation of Bacteria

Different types of bacteria in various forms are found all around us, and it is a microbiologist’s job to be able to identify these bacteria. Using various staining techniques and physiological tests, an isolated bacterium can be identified. In this experiment, a single bacterial colony was isolated form Mycorrhizal spores, and further tests done on that colony.

Sub culturing was done after each week to ensure that the bacterium has sufficient nutrients required for optimum growth that will last the duration of the entire experiment. A flow chart was created based on the results of the physiological tests in order to identify the isolated bacterium. After 4 weeks, the isolated bacterium was identified as XXXXX for reasons stated in the results and discussion.

The main goal of this experiment was to identify the isolated bacterium that was obtained from Mycorrhizal spores. In order to identify the bacterium, the experiment was conducted in 4 parts: (a) isolation of an unknown bacterium from soil; (b) identification of the bacterium using various staining techniques; (c) determining the motility of the bacterium; and (d) determining the physiological characteristics of the bacterium. Part (a) of the experiment involves isolating a single bacterial colony from the culture.

The remaining 3 parts will be conducted on that colony. In part (b), it is shown that various staining techniques test for different characteristics. As the name suggests, a gram stain is conducted to identify the bacteria as gram negative or gram positive. Two other stains were carried out. To determine the motility of the bacterium, wet mounts of the bacterium were observed and the motility was confirmed by using soft agar plates and soft agar deeps for part (c).

The physiological characteristics were identified in part (d). Some of these tests include growth temperatures and salt tolerance, degradation of polysaccharides, proteins and lipids, oxygen requirements etc. Based on the results for the above, the unknown bacterium can be identified by comparing it to cultures in the Bergey’s manual. A flow chart can be drawn up to correctly identify the bacterium by using the physiological test results.