aob

AOB is an acronym with multiple meanings, depending on context. In organizational and business settings, AOB stands for All Other Business, referring to items not on the formal agenda that are raised during a meeting's concluding segment. Practices vary by organization; some places require advance notice or limit discussion time to prevent disruption of the main agenda.

In microbiology, AOB refers to ammonia-oxidizing bacteria, a group of chemolithoautotrophic microorganisms that perform the first step of nitrification by oxidizing ammonia (NH3) to nitrite (NO2-). They are strictly aerobic and require oxygen. They fix carbon dioxide to support growth, using energy derived from ammonia oxidation. Key enzymes include ammonia monooxygenase (AMO) and hydroxylamine oxidoreductase (HAO). They inhabit soils, freshwater and marine environments, wastewater treatment systems, and biofilms. Genera commonly studied include Nitrosomonas, Nitrosospira, Nitrosococcus, and others. AOB are distinct from ammonia-oxidizing archaea (AOA) and from nitrite-oxidizing bacteria (NOB), which complete the nitrification process by oxidizing nitrite to nitrate. In environmental engineering, controlling AOB activity is important for nitrification processes; in ecology, their activity affects nitrogen cycling and ecosystem nutrient dynamics. They can be inhibited by heavy metals, chlorine, and high concentrations of ammonia.