Could soil microbes offer a solution for the climate crisis?

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Research from Arpita Bose’s lab combines nature with the laboratory to innovate solutions to our global climate crisis

Climate change mitigation is largely focused on reducing anthropogenic carbon greenhouse gas emissions (e.g.., carbon dioxide, CO₂; methane.₄), which continue to Increase. An additional consideration is the interaction and exchange of atmospheric carbon with Earth’s surfaces such as oceans, lakes, and wetlands, otherwise known as the global carbon cycle. These environments are not only important in the global Carbon Cycle, but also play an important role. They are vulnerableClimate change is causing an increase in carbon concentrations and temperatures. To address the climate crisis we are currently facing, we must fill in the carbon cycle gaps and develop new strategies to remove carbon from the atmosphere. Could one of the solutions to the climate crisis be right in front of us?

Solving the climate crisis might be possible with soil microbes, and their diverse metabolisms

There are many microbial communities within soils and sediments with diverse metabolisms. Extracellular electron uptake is one example of such a metabolism. (EEU)Certain microbes are able to obtain electrons from oxidizing minerals in the surrounding environment. Some EEU-capable microbes also have the ability to become photoautotrophs, which can convert carbon dioxide in the environment to organic carbon needed for photosynthesis. These bacteria can remove CO.₂The carbon cycle is affected by the metabolism of the microbes. However, this effect is not well understood. These microbes have carbon storage systems that allow them to store carbon in their bodies as a survival mechanism in case of limiting growth conditions. These carbon storage systems such as the synthesis or polyhydroxybutyrate (PHBs) are natural pathways to the synthesis or bioplastics. They may also be vital for the mitigation of climate crisis.

Scanning electron micrographs of pEEU-capable Rhodovulum sulfidophilum bacteria isolated from Trunk River Estuary in Woods Hole, Massachusetts. Credit: Arpita Bose and Rajesh Singh — Scanning electron microscopes of Rhodovulum sulfidophilum bacteria, pEEU-capable, isolated from Trunk River Estuary at Woods Hole in Massachusetts. Credit: Rajesh Singh and Arpita Bose

pEEU for carbon capture, sustainable biofuel synthesis and sustainable biofuel production

It is not a new idea to use photoautotrophs in the solution of climate and energy crises. For CO reduction, tree planting and forest conservation have been long-promised.₂The atmosphere. For sustainable generation of biofuels, it has been suggested that large-scale cultivation of photosynthetic alga and cyanobacteria be done. n-butanol and other naturally synthesized products These photoautotrophs are oxygen-evolving which reduces the efficiency natural product biosynthesis.

The Bose lab studies anoxygenic (non-oxygen-evolving), purple non-sulfur, pEEU-capable bacteria from marine and freshwater environments to improve our knowledge of pEEU molecular mechanisms, determine pEEU’s prevalence in natural environments, and bend this metabolism to our will as a climate solution. To measure the ability of microbes, such as pEEU, to obtain electrons at different potentials mimicking natural sources in a habitat, they are placed in a bioelectrochemical (BES). Recent work at the Bose laboratory connected pEEU to CO under illumination.₂Fixation, and showed synthesis PHBs n-butanolCO could be used.₂As carbon input. These microbes could theoretically perform carbon-neutral or negative synthesis of biofuels, bioplastics, and other products within a BES powered with solar radiation. This would be a truly sustainable solution. To improve the genetic engineering of these systems, it is necessary to identify additional species that are able to produce pEEUs and to characterize their uptake pathways.

Carbon sequestration in freshwater ecosystems and marine wetland ecosystems

The Bose group also works outside of the laboratory to understand carbon capture in an important, but undervalued ecosystem. freshwater wetlands. At less than 10% of Earth’s land surface, wetlands can hold up to 30% of carbon sequestered in soil. The isolation of pEEU-capable bacteria by a Missouri freshwater wetlandThese photoautotrophs may play a role in carbon storage success, according to our research. We have also studied pEEU capable microbes. marine wetlandsWoods Hole (Massachusetts). Further research is needed Understanding the carbon cycleThese dynamic environments are known to have high microbial populations, microbial carbon fixation and microbial growth rates. This will help to conserve these ecologically significant ecosystems as well as provide nature-based solutions to the climate crises.

Trunk River Estuary in Woods Hole, Massachusetts, a marine wetland ecosystem. Credit - Sandra Brosnahan, Woods Hole Coastal and Marine Science Center — Trunk River Estuary is a marine ecosystem in Woods Hole (Massachusetts). Credit – Sandra Brosnahan, Woods Hole Coastal and Marine Science Center

Wetlands are Threatened ecosystemsTheir role in Carbon sequestrationIt is often overlooked. These observations shed light on the need to preserve and expand these ecosystems to maximize carbon sequestration (including pEEU driven carbon dioxide fixation). Other than carbon sequestration, wetlands serve many other purposes such as denitrification(where excess nitrogen can be converted microbially into dinitrogen gas), streambank stabilization, and phosphorus retention. There are many unique microbes in the wetlands that could be treasure troves waiting to be discovered. These microbes could be used as models for sustainable biosynthesis in future.