Advancing towards a sustainable and cleaner environment
Oeiras, 04 December 2023
We are living a global environmental crisis. As carbon dioxide (CO2) levels rise in the atmosphere, pollutants accumulate in the environment and the demand for more energy increases, the search for solutions is getting ever more urgent. The Bacterial Energy Metabolism lab, led by Inês Cardoso Pereira, at ITQB NOVA, focuses on using biological systems (bacteria or their machinery) for the development of sustainable technological applications to address these problems. Recently, the lab published three new studies characterizing important biological systems that can be exploited to produce energy, remove environmental contaminants and convert CO2 for a greener circular economy.
Geobacter sulfurreducens are bacteria capable of discharging electrons (negatively charged particles) to the outside of the cell as part of their respiration. This microbe is a model system for technologies using microorganisms to produce bioelectricity and added-value compounds, or to get rid of pollutants. In a project led by Américo G. Duarte, a senior researcher in the lab, scientists explored the role of one of the proteins important for electron transfer to the bacteria’s exterior, demonstrating its relevance for the process involved in bioelectricity generation. The work, published in Protein Science and first-authored by Andreia Pimenta, involved collaboration between researchers from ITQB NOVA, the NOVA School of Science and Technology, the University of East Anglia and the University of Essex.
The second study, published in Nature Communications, is the outcome of a fruitful collaboration with the Environmental Biotechnology Laboratory from the École Polytechnique Fédérale de Lausanne, in Switzerland. In a paper with Américo G. Duarte as first co-author, researchers used cryoelectron microscopy (cryo-EM) to define the structure of a complex involved in a type of bacterial respiration that uses halogenated compounds. These compounds are often found in pesticides, plasticizers, ink and refrigerants. Besides determining the first structure of such a protein, researchers revealed important details about its interactions. “These bacteria can grow while detoxifying their surroundings. They can be used to clean water and soil environments polluted with compounds that are hard to degrade and which often are toxic to animals and plants”, says Duarte.
The third publication deals with a bacterial enzyme capable of converting CO2, but which can be inactivated by oxygen, hindering its use. The study published in Nature Chemical Biology was first authored by Ana Rita Oliveira and Cristiano Mota, continuing a collaboration with Maria João Romão’s group at the NOVA School of Sciences and Technology and researchers from the Aix Marseille University. Previously, the teams had described how this enzyme, from Desulfovibrio vulgaris Hildenborough, can be handled in the presence of oxygen, but the basis for this tolerance was not known. Now, they unveiled how this happens, showing that the enzyme presents an oxygen-tolerant resting state where it can be handled in air, and which is converted to the active state under optimal conditions. This property is associated with a fitness advantage that makes this enzyme an excellent model system that has been explored in different setups for biotechnological conversion of CO2.
“These three studies reveal how we can explore microorganisms to protect the environment”, says Inês Cardoso Pereira. “These are all biological systems that already exist in nature. We just need to learn how they work to make the most of them.”
ITQB NOVA researchers Nuno Machado, Américo G. Duarte, Inês Cardoso Pereira, Raquel Bernardino, Gonçalo Manteigas, Andreia Pimenta, Teresa Catarino, Guilherme Martins and Rita Manuel
The authors thank the technical support of João Carita from ITQB NOVA Microbial Cell Production facility and funding from Fundação para a Ciência e Tecnologia, MOSTMICRO-ITQB NOVA research unit (UIDB/04612/2020 and UIDP/04612/2020) and Associated Laboratory LS4FUTURE (LA/P/0087/2020).
Original papers:
Characterization of the Inner Membrane Cytochrome ImcH from Geobacter Reveals Its Importance for Extracellular Electron Transfer and Energy Conservation
Andreia I. Pimenta., Catarina M. Paquete, Leonor Morgado, Marcus J. Edwards, Thomas A. Clarke, Carlos A. Salgueiro, Inês A. C. Pereira, and Américo G. Duarte. 2023
Structure of a Membrane-Bound Menaquinol: Organohalide Oxidoreductase
Lorenzo Cimmino, Américo G. Duarte, Dongchun Ni, Babatunde E. Ekundayo, Inês A. C. Pereira, Henning Stahlberg, Christof Holliger, Julien Maillard. 2023.
An allosteric redox switch involved in oxygen protection in a CO2 reductase
Ana Rita Oliveira, Cristiano Mota, Guilherme Vilela-Alves, Rita Rebelo Manuel, Neide Pedrosa, Vincent Fourmond, Kateryna Klymanska, Christophe Léger, Bruno Guigliarelli, Maria João Romão & Inês A. C. Pereira
