Formic acid in focus
An artificial key enzyme opens up the conversion of CO2 via formic acid to raw materials
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Formate, the salt of formic acid, is seen as an important future pivot for sustainable biotechnologies. A team at the Max Planck Institute for Terrestrial microbiology has developed an enzyme that efficiently converts formate to formaldehyde. This is crucial for the sustainable conversion of CO2 into valuable raw materials. The new enzyme, FAR, tolerates high formate concentrations: an important prerequisite for industrial processes.
Multipipettes in the high-throughput robot
Franka Eiche / Copyright: MPI für terrestrische Mikrobiologie
A carbon-neutral bioeconomy requires processes that bind CO2 efficiently and convert it into valuable products. Formic acid, or rather its salt formate, is considered a promising candidate: it can be produced from CO2 using renewable electricity, is easy to transport, non-toxic and versatile. Among other things, research is focusing on microorganisms that are "fed" with formic acid produced from CO2 and use it to produce basic chemicals or fuels.
A team led by Dr. Maren Nattermann at the Max Planck Institute for Terrestrial Microbiology has developed a tailor-made enzyme that carries out the central conversion step precisely and stably in a single enzymatic process. Incorporation of a synthetic metabolic bypass
The enzymatic solution builds on previous research in which the team established a completely synthetic formyl phosphate pathway in bacteria. Previously, only certain bacteria were able to utilize formic acid. Natural metabolic pathways bypass the intermediate formaldehyde, which serves as an important starting point for the integration of CO2 into the cell metabolism. The researchers constructed an artificial bridge: a synthetic formyl phosphate metabolic pathway, which they incorporated into living E. coli bacteria. Cooperation partner Dr. Sebastian Wenk (University of Groningen) explains: "Our work showed that a synthetic metabolic pathway for processing formate works in living organisms - an important step towards the development of biotechnologically usable microorganisms that can use formate obtained from CO2 to produce food, fuels and materials." The formaldehyde is immediately processed by the cell and does not accumulate.
However, the connection to the cell metabolism must be robust - after all, it competes with the well-established natural metabolism that has evolved over millions of years. Until now, only complex and susceptible multi-stage enzymatic cascades have existed, which release sensitive intermediate products such as formyl phosphate or formyl-CoA - molecules that break down easily or enter into undesirable side reactions. From a biotechnological point of view, the goal is a "full formate diet" in which bacteria grow exclusively with formic acid, without costly additives. A single enzyme takes the decisive step
The group recently achieved a decisive breakthrough: a tailor-made formate reductase enzyme that converts formic acid to formaldehyde precisely and robustly. The enzyme, called FAR (formate reductase), is based on a carboxylic acid reductase (CAR) from the bacterium Mycobacteroides abscessus. The CAR enzyme was modified through targeted mutagenesis and high-throughput screening so that it preferentially selects small molecules such as formate. "With FAR, we have for the first time a single, robust enzyme that reliably reduces formate to formaldehyde - exactly where many biotechnological pathways begin," explains Max Planck research group leader Dr. Maren Nattermann. "We are thus creating a missing building block for future bioconversions that are based directly on CO₂-based raw materials."
"The most important thing is that our enzyme tolerates even high formate concentrations - because previous systems failed almost completely under these conditions," adds Philipp Wichmann, first author of the study. It is precisely this stability that makes FAR attractive for industrial processes in which formate is produced electrochemically in very high concentrations.
Without the use of high-throughput methods, this result would not have been achievable in a short space of time. "After screening around 4,000 variants, we achieved a five-fold increase in formaldehyde production," explains Maren Nattermann.
With FAR, an enzyme is now available that can be used in living cells as well as in cell-free systems or electrobiochemical production lines. In future, basic chemicals, bioplastics or fuels could be produced from CO2-based formate. The researchers are already planning to combine FAR with other synthetic metabolic pathways, for example to produce energy-rich molecules.
Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.
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