Bacterial assimilatory nitrate uptake and reduction

A reusable bacterial module for reducing nitrate through nitrite to ammonium for biosynthesis. In complete whole-cell realizations that use extracellular nitrate, a nitrate-import system supplies the intracellular pool before an assimilatory molybdoenzyme reduces nitrate to nitrite and a siroheme-containing NirBD complex performs the six-electron reduction of nitrite to ammonium. Uptake is optional at the reusable module boundary so that the two core reductions can also be instantiated from intracellular nitrate. The module stops at ammonium; incorporation through GS-GOGAT is a separate module. Respiratory nitrate reduction, denitrification, and dissimilatory nitrate reduction to ammonium are outside this boundary.

CONCRETE denotes a grounded bacterial pathway realization, not a species-specific member list. Nitrate uptake is optional at this reusable boundary but is required when the realization begins with extracellular nitrate. ONE_OR_MORE is relaxed modeling: transporter systems can coexist, while coexistence or strict exclusivity of nitrate-reductase architectures is not asserted without organism-specific evidence. Molecular functions occur only on leaf annotons, and no generic localization is asserted.