The American Society for Microbiology (ASM) announced earlier this year that researchers from Washington State University (WSU) successfully engineered strains of the nitrogen (N)-fixing soil bacterium Azotobacter vinelandii, which enabled these microorganisms to produce ammonia (NH3) in pretty high concentrations, and in essence giving us a way to possibly replace the use of fertilizers in the future entirely.
Part of the goal of the research team was to understand the intricacies surrounding nitrogen fixation, or the process in which organic compounds collect nitrogen as part of what’s known as the nitrogen cycle in nature.
“Our work helps provide a more complete, fundamental understanding of the factors that underpin gene expression in a model [nitrogen-fixing] microorganism and defines the biochemistry that brings about ammonia excretion in A. vinelandii,” added WSU Institute of Biological Chemistry assistant research professor Dr. Florence Mus, who led the work now published in the journal Applied and Environmental Microbiology.
To do so, Dr. Mus and the research team made use of gene editing techniques to impart ammonia production to A. vinelandii at constant levels “regardless of environmental conditions surrounding the bacteria,” according to the aforementioned ASM press release. A. vinelandii was already known to be capable of converting nitrogen into ammonia, which made them the ideal testbed for what could be the future of crop fertilizers.
Testing the results of the experiment involved adding the bioengineered bacteria to soils where rice plants were grown. Further analyses of the surrounding plants revealed that they were indeed taking up the ammonia produced by the A. vinelandii surrounding them—a remarkable feat that illuminates tantalizing opportunities for the future of agriculture.
All in all, the result was a batch of bioengineered bacteria that were capable of excreting ammonia at a high enough concentration to fertilize rice plants. “We presented conclusive evidence that ammonia released is transferred to the rice plants,” added Mus. “Our unique approach aims to provide new solutions to the challenge of replacing industrial fertilizers with custom-made bacteria.”
Dr. Mus and the team hope that their research can reduce water pollution levels in the ocean, which are in part due to excess nitrogen-based fertilizers getting washed off plants and into waterways. Part of their efforts working towards this quest is designing future iterations of bacteria with varying rates of ammonia production, which they hope can help limit excess ammonia production for agriculture.
“Successful widespread adoption of these biofertilizers for farming would reduce pollution, provide sustainable ways of managing the nitrogen cycle in soil, lower production costs and increase profit margins for farmers and enhance sustainable food production by improving soil fertility,” said Dr. Mus.
References
- ASM Communications. (2022, February 15). Engineered Bacterial Strains Could Fertilize Crops, Reduce Waterways Pollution. American Society of Microbiology. https://asm.org/Press-Releases/2022/Feb-2022/Engineered-Bacterial-Strains-Could-Fertilize-Crops
- Coxworth, B. (2022, February 18). Engineered ammonia-producing bacteria could replace crop fertilizers. New Atlas. https://newatlas.com/science/engineered-ammonia-producing-bacteria-crop-fertilizers/
- Mus, F., Khokhani, D., MacIntyre, A. M., Rugoli, E., Dixon, R., Ané, J.-M., & Peters, J. W. (2022). Genetic determinants of ammonium excretion in nifL mutants of Azotobacter vinelandii. Applied and Environmental Microbiology, AEM.01876-21. https://doi.org/10.1128/AEM.01876-21
