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Amino acids produced from waste could provide sustainable plant feed

farming land

24 October 2019

A way to produce a greener fertiliser could be a step closer as a new process transforms waste into citrulline.

Researchers from The Australian National University, in collaboration other organisations including  CSIRO, have developed a method whereby ammonia from a variety of sources can be transformed into citrulline which is rich in nitrogen and essential for plant growth. 

The process takes ammonia from waterways and combines it with atmospheric carbon dioxide to produce citrulline found in fruit such as watermelons. The research team explains that combining ammonia with atmospheric CO2 produces a compound called carbamate which can then combined with genetically engineered E.coli bacteria. Enzymes convert the carbamate into carbamoyl phosphate. The carbon and nitrogen in the carbamoyl molecule are then fixed onto the amino acid ornithine to produce citrulline.

Compared with the traditional Haber-Bosch route for producing fertiliser, the researchers say that this route is far less energy intensive. The research team have found the enzyme system to be ‘remarkably stable and versatile,’ converting ammonia at a wide range of concentrations without any issues.
Researchers said that ammonia at concentrations similar to those found in municipal waste, all the way up to heavily contaminated industrial waste can be used.

For further details visit this month’s Chemistry & Industry

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