How many tubes of OF media are inoculated, and what are the atmospheric conditions?

The correct approach to using OF (Oxidation-Fermentation) media involves inoculating two tubes: one tube is left uncovered to allow for aerobic conditions, while another is covered with mineral oil to create anaerobic conditions. This dual set-up is essential for determining the metabolic pathway utilized by the organism being tested.

The aerobic tube allows for the assessment of whether the organism can oxidize carbohydrates in the presence of oxygen, while the anaerobic tube reveals whether the organism can ferment carbohydrates when oxygen is not available. By analyzing the color change in both tubes, it's possible to identify the metabolic capabilities of the microorganism, differentiating between oxidative and fermentative processes. The presence or absence of color change provides crucial information about the organism’s energy metabolism and can assist in its identification.

This procedure is standard practice in microbiology for testing the metabolic behaviors of bacteria, especially when distinguishing between species that utilize oxygen versus those that do not. The correct answer reflects an accurate understanding of the inoculation process and the atmospheric conditions required for the experiment.