Food production heavily depends on ammonia-containing fertilizers to improve crop yield and profitability. However, ammonia production is challenged by huge energy demands and the release of ~2% of global CO2. To mitigate this challenge, many research efforts have been made to develop bioprocessing technologies to make biological ammonia. This review presents three different biological approaches that drive the biochemical mechanisms to convert nitrogen gas, bioresources, or waste to bio-ammonia. The use of advanced technologies-enzyme immobilization and microbial bioengineering-enhanced bio-ammonia production. This review also highlighted some challenges and research gaps that require researchers' attention for bio-ammonia to be industrially pragmatic.
Keywords: bioengineering; biological ammonia; bioprocessing; enzyme immobilization; fermentation.