In which biochemical category does Actinobacillus spp. fall?

Actinobacillus spp. falls into several biochemical categories. They are considered fermenters, meaning they can metabolize carbohydrates anaerobically and produce various end products through fermentation processes. This metabolic capability is crucial for their survival and growth in different environments, particularly in the host.

Additionally, Actinobacillus spp. are urease negative, indicating they do not produce the enzyme urease which breaks down urea into ammonia and carbon dioxide. This characteristic helps differentiate them from other bacterial species that may produce urease.

Furthermore, they are also indole negative. This means that they do not have the enzymatic ability to convert tryptophan to indole, a property used in various biochemical tests to help identify bacterial species.

Since Actinobacillus spp. exhibit all these biochemical characteristics—fermenting capabilities, urease negativity, and indole negativity—they are categorized correctly under all the listed categories. Thus, the inclusion of "all of the above" as the answer accurately captures the biochemical profile of Actinobacillus spp.