With formic acid towards CO2 neutrality
Researchers develop a new method for the sustainable use of carbon
dioxide

Date:
May 15, 2023
Source:
Max-Planck-Gesellschaft
Summary:
Researchers develop a new method for the sustainable use of
carbon dioxide.


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FULL STORY ==========================================================================
New synthetic metabolic pathways for fixation of carbon dioxide could
not only help to reduce the carbon dioxide content of the atmosphere,
but also replace conventional chemical manufacturing processes for pharmaceuticals and active ingredients with carbon-neutral, biological processes. A new study demonstrates a process that can turn carbon dioxide
into a valuable material for the biochemical industry via formic acid.

In view of rising greenhouse gas emissions, carbon capture, the
sequestration of carbon dioxide from large emission sources, is an urgent issue. In nature, carbon dioxide assimilation has been taking place for millions of years, but its capacity is far from sufficient to compensate human-made emissions.

Researchers led by Tobias Erb at the Max Planck Institute for Terrestrial Microbiology are using nature's toolbox to develop new ways of carbon
dioxide fixation. They have now succeeded in developing an artificial
metabolic pathway that produces the highly reactive formaldehyde
from formic acid, a possible intermediate product of artificial
photosynthesis. Formaldehyde could be fed directly into several metabolic pathways to form other valuable substances without any toxic effects. As
in the natural process, two primary components are required: Energy and
carbon. The former can be provided not only by direct sunlight but also
by electricity -- for example from solar modules.

Formic acid is a C1 building block Within the added-value chain, the
carbon source is variable. carbon dioxide is not the only option here,
all monocarbons (C1 building blocks) come into question: carbon monoxide, formic acid, formaldehyde, methanol and methane.

However, almost all of these substances are highly toxic -- either
to living organisms (carbon monoxide, formaldehyde, methanol) or
to the planet (methane as a greenhouse gas). Only formic acid, when
neutralised to its base formate, is tolerated by many microorganisms in
high concentrations.

"Formic acid is a very promising carbon source," emphasizes Maren
Nattermann, first author of the study. "But converting it to
formaldehyde in the test tube is quite energy-intensive." This is
because the salt of formic acid, formate, cannot be converted easily
into formaldehyde. "There's a serious chemical barrier between the
two molecules that we have to bridge with biochemical energy -- ATP --
before we can perform the actual reaction." The researcher's goal was
to find a more economical way. After all, the less energy it takes to
feed carbon into metabolism, the more energy remains to drive growth or production. But such a path does not exist in nature. "It takes some
creativity to discover so-called promiscuous enzymes with multiple
functions," says Tobias Erb. "However, the discovery of candidate
enzymes is only the beginning. We're talking about reactions that you can
count along with since they're so slow -- in some cases, less than one
reaction per second per enzyme. Natural reactions can happen a thousand
times faster." This is where synthetic biochemistry comes in, says Maren Nattermann: "If you know an enzyme's structure and mechanism, you know
where to intervene. Here, we benefit significantly from the preliminary
work of our colleagues in basic research." High-throughput technology
speeds up enzyme optimization The optimization of the enzymes comprised
of several approaches: building blocks were specifically exchanged, and
random mutations were generated and selected for capability. "Formate
and formaldehyde are both wonderfully suited because they penetrate cell
walls. We can put formate into the culture medium of cells that produce
our enzymes, and after a few hours convert the formaldehyde produced
into a non-toxic yellow dye," explains Maren Nattermann.

The result would not have been possible in such a short time without
the use of high-throughput methods. To achieve this, the researchers
cooperated with their industrial partner Festo, based in Esslingen,
Germany. "After about 4000 variants, we achieved a fourfold improvement
in production," says Maren Nattermann. "We have thus created the basis
for the model mikrobe Escherichia coli, the microbial workhorse of biotechnology, to grow on formic acid. For now, however, our cells can
only produce formaldehyde, not convert it further." With collaboration
partner Sebastian Wenk at the Max Planck Institute of Molecular Plant Physiology, the researchers are currently developing a strain that
can take up the intermediates and introduce them into the central
metabolism. In parallel, the team is conducting research with a working
group at the Max Planck Institute for Chemical Energy Conversion headed
by Walter Leitner on the electrochemical conversion of carbon dioxide
to formic acid. The long-term goal is an "all-in-one platform" -- from
carbon dioxide via an electrobiochemical process to products like insulin
or biodiesel.

* RELATED_TOPICS
o Matter_&_Energy
# Organic_Chemistry # Biochemistry # Graphene #
Electronics
o Earth_&_Climate
# Air_Quality # Global_Warming # Forest # Air_Pollution
* RELATED_TERMS
o Carbon_dioxide o Forest o Carbon_dioxide_sink
o Carbon_monoxide o Fullerene o Fossil_fuel o
Sustainable_agriculture o Carbon-14

========================================================================== Story Source: Materials provided by Max-Planck-Gesellschaft. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Maren Nattermann, Sebastian Wenk, Pascal Pfister, Hai He, Seung
Hwan Lee,
Witold Szymanski, Nils Guntermann, Fayin Zhu, Lennart Nickel,
Charlotte Wallner, Jan Zarzycki, Nicole Paczia, Nina Gaissert,
Giancarlo Francio`, Walter Leitner, Ramon Gonzalez, Tobias
J. Erb. Engineering a new-to- nature cascade for phosphate-dependent
formate to formaldehyde conversion in vitro and in vivo. Nature
Communications, 2023; 14 (1) DOI: 10.1038/ s41467-023-38072-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230515131949.htm

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