Which of the following genera is NOT typically oxidase-positive?

Proteus is the correct answer because it is typically oxidase-negative. The oxidase test is used in microbiology to determine if an organism produces cytochrome c oxidase, an enzyme involved in the electron transport chain.

In contrast, Moraxella and Neisseria are both genera known for their oxidase-positive reaction. They are part of the family Neisseriaceae and are often found in clinical specimens. Aeromonas, which can be isolated from various aquatic environments, is also oxidase-positive.

Understanding which organisms are oxidase-positive helps in differential identification of bacteria, particularly when working with Gram-negative rods. The oxidase test can aid in distinguishing closely related genera or species in the laboratory setting, particularly during pathogen identification. Thus, recognizing that Proteus does not produce this specific enzyme can help narrow down tests and identifications in clinical microbiology.