Scientists reveal the potential of a tiny soil bacterium to beat the Haber-Bosch process

A new review finds that biological ammonia production offers strong potential as a cleaner, greener alternative to the costly Haber-Bosch process.

Microbes such as Azotobacter can produce ammonia under ambient conditions and atmospheric pressure, unlike the traditional method that requires temperatures in the hundreds and high pressure, according to Dr. Nuttavut Kosem of Mitsui Chemicals, Inc. Carbon Neutral Research Center (MCI-CNRC), Kyushu University, who led the review.

The review, ‘Exploring Azotobacter: A Nitrogen-Fixing Microorganism as a Powerhouse for Sustainable and Green Ammonia Synthesis’ has recently appeared in the Journal of Applied Microbiology, an Applied Microbiology International publication.

Solar-to-chemical energy conversion

Dr Kosem’s research focuses on solar-to-chemical energy conversion through the integration of photocatalysts and biocatalytic enzymes to develop sustainable biofuel production systems.

“The global production of ammonia, a key component for fertilizers and emerging energy systems, currently relies on the Haber–Bosch process, which consumes large amounts of energy and contributes significantly to carbon emissions. This creates an urgent need for more sustainable and environmentally friendly alternatives,” he explained.

“In our work, we aimed to explore how biological systems can produce ammonia under mild, ambient conditions by using natural enzymatic processes. Specifically, we sought to understand how to improve the efficiency, stability, and scalability of these biological pathways to support future carbon-neutral ammonia production technologies.”

Nitrogenase enzymes

The study reviewed and analyzed how biological systems can produce ammonia using nitrogenase enzymes under ambient conditions. 

The team focused on understanding the fundamental mechanisms of biological nitrogen fixation, including how nitrogenase converts atmospheric nitrogen into ammonia and what factors influence its efficiency. They also examined how different biological and environmental conditions affect this process.

“We then explored recent advances in biotechnology aimed at improving ammonia production in these systems. This included strategies such as genetic engineering to enhance enzyme expression, metabolic engineering to improve energy and electron supply, and the development of hybrid systems that combine biological catalysts with external energy sources. Emerging approaches such as photobiocatalysis and bioelectrochemical systems were also considered as ways to further boost performance,” Dr Kosem said.

“Overall, we found that biological ammonia production has strong potential as a sustainable alternative to conventional industrial methods. With ongoing improvements in enzyme efficiency, cellular stability, and system design, these bio-based approaches could be developed into scalable technologies for carbon-neutral ammonia production in the future.”

Contrasting processes

Dr Kosem admitted he was surprised by the remarkable contrast between the Haber–Bosch process and biological ammonia production. 

“While the Haber–Bosch process requires harsh conditions, including high temperature (400–500 °C) and high pressure (150–300 atm), biological systems can produce ammonia under ambient conditions (~20–30 °C and atmospheric pressure),” he said.

“Although nitrogenase is highly sensitive to oxygen, which limits its practical application, certain microorganisms such as Azotobacter have evolved effective protection mechanisms.

“These include the formation of an extracellular polysaccharide capsule, respiratory protection through elevated oxygen consumption, reactive oxygen species detoxification, and regulation by the NifL–NifA system.

”These unique characteristics enable Azotobacter to maintain nitrogenase activity under aerobic conditions, making it a promising candidate for future development toward commercial-scale, sustainable ammonia production.”

Harnessing bacteria

Understanding the biological mechanisms and key factors that influence microbial ammonia production will allow scientists to better harness these systems for sustainable applications. 

“Unlike conventional methods, biological processes operate under mild conditions, reducing energy consumption and environmental impact. In particular, Azotobacter vinelandii offers a unique advantage due to its ability to protect oxygen-sensitive nitrogenase, enabling efficient ammonia production under aerobic conditions,” Dr Kosem said.

“This oxygen tolerance improves system stability and practicality, bringing biological ammonia production closer to real-world and industrial-scale implementation.

Next steps

“Looking ahead, advancing biological ammonia production will depend on improving nitrogenase performance through genetic engineering, enabling higher activity and efficiency. 

“At the same time, developing biofilm-based or immobilization strategies will be important to enhance the stability and lifespan of microorganisms, allowing for more robust and continuous production. Together, these approaches will help bridge the gap between laboratory research and large-scale industrial applications.”

This study was led by Dr. Nuttavut Kosem at the Mitsui Chemicals, Inc. Carbon Neutral Research Center (MCI-CNRC), Kyushu University. The work was financially supported by MCI-CNRC and the World Premier International Research Center Initiative (WPI) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, through the Japan Society for the Promotion of Science (JSPS), under a Grant-in-Aid for Specially Promoted Research.

‘Exploring Azotobacter: A Nitrogen-Fixing Microorganism as a Powerhouse for Sustainable and Green Ammonia Synthesis’ is published in the Journal of Applied Microbiology.