Article
Ecology
Jimyung Moon, Anja Schubert, Lara M. Waschinger, Volker Mueller
Summary: Methyl groups in anoxic environments can be used as carbon and energy sources by microorganisms through oxidation to CO2 and electron transfer to an acceptor. This study describes the generation of a mutant acetogen that stops methyl group oxidation at the formate level and reoxidizes reduced electron carriers by CO2 reduction to acetate. The mutant can grow on glycine betaine as a methyl group donor and produce formate alongside acetate. This genetic reprogramming of an acetogen into a formatogen has implications for both biotechnology and the mechanism of electron transfer in anoxic environments.
Article
Biotechnology & Applied Microbiology
Sandra Weitz, Maria Hermann, Sonja Linder, Frank R. Bengelsdorf, Ralf Takors, Peter Duerre
Summary: Two different isobutanol synthesis pathways were expressed in two model acetogenic bacteria, showing significant influence of pathway selection and reaction conditions on isobutanol production in different bacteria.
FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY
(2021)
Article
Microbiology
Dragan Trifunovic, Jimyung Moon, Anja Poehlein, Rolf Daniel, Volker Mueller
Summary: The study demonstrates that Acetobacterium woodii DSM1030 can utilize glycerol and dihydroxyacetone as growth substrates, converting them to acetate through related metabolic pathways, while stably maintaining growth.
ENVIRONMENTAL MICROBIOLOGY
(2021)
Article
Microbiology
Jimyung Moon, Judith Donig, Sina Kramer, Anja Poehlein, Rolf Daniel, Volker Muller
Summary: This study provides detailed insights into formate metabolism and growth characteristics of Acetobacterium woodii, revealing key genes and enzymes involved in formate metabolism.
ENVIRONMENTAL MICROBIOLOGY
(2021)
Article
Biochemical Research Methods
Maximilian Flaiz, Tina Baur, Jana Gaibler, Christian Kroely, Peter Duerre
Summary: Anaerobic bacteria are potential biocatalysts for producing industrial products from nonfood feedstocks. However, the use of fluorescent reporters is limited in anaerobic conditions. This study established green and red fluorescent reporter proteins for different solventogenic and acetogenic bacteria, enabling multicolor approaches to investigate cell dynamics, gene expression, and protein localization in anaerobic conditions.
ACS SYNTHETIC BIOLOGY
(2022)
Article
Biotechnology & Applied Microbiology
Christian Oeppinger, Florian Kremp, Volker Mueller
Summary: This study focuses on the structure and electron donor of methylene-tetrahydrofolate reductase, providing evidence that reduced ferredoxin cannot be the physiological electron donor under in vivo conditions. The study also discusses the possible reasons for the discrepancy between in vitro and in vivo functions, and presents a model for the incorporation of the MetVF-type MTHFR into metabolism to achieve a positive ATP yield.
INTERNATIONAL MICROBIOLOGY
(2022)
Article
Biochemistry & Molecular Biology
Amaravadhi Harikishore, Wuan-Geok Saw, Priya Ragunathan, Dennis Litty, Thomas Dick, Volker Mueller, Gerhard Gruber
Summary: This study elucidated the differences in the amino acid composition and structural features of the mycobacterial F-ATP synthase compared to other counterparts, paving the way for discovering molecules that can interfere with the regulative mechanisms of this essential energy converter. The essentiality of the mycobacterial peripheral stalk subunit delta for effective catalysis was demonstrated, leading to the identification of a potent subunit delta inhibitor. Targeting the delta subunit shows potential for developing F-ATP synthase inhibitors.
ACS CHEMICAL BIOLOGY
(2022)
Article
Biotechnology & Applied Microbiology
Nilanjan Pal Chowdhury, Dennis Litty, Volker Mueller
Summary: Acetobacterium woodii is an acetogen that can utilize methanol to produce acetate, making it a potential candidate for the production of bio-commodities. In this study, researchers introduced a butyrate production operon from a related acetogen into A. woodii, enabling stable production of butyrate from methanol. The addition of electrons in the form of carbon monoxide further enhanced butyrate production by recombinant A. woodii strains, expanding its product spectrum.
INTERNATIONAL MICROBIOLOGY
(2022)
Article
Microbiology
Dennis Litty, Florian Kremp, Volker Mueller
Summary: Acetogenic bacteria such as Acetobacterium woodii utilize the Wood-Ljungdahl pathway for CO2 fixation and energy conservation, converting methyl group containing substrates to acetate. Different pathways for the conversion of methyl-group containing substrates enable acetogens to adapt to various ecological niches and syntrophic communities.
ENVIRONMENTAL MICROBIOLOGY
(2022)
Article
Microbiology
Florian P. Rosenbaum, Anja Poehlein, Rolf Daniel, Volker Mueller
Summary: M. thermoacetica is capable of using dimethyl sulfoxide (DMSO) as an electron acceptor, which promotes its growth on glucose or H-2 + CO2. DMSO reductase activity was observed in the membranes of M. thermoacetica, with the enzyme exhibiting high activity at pH 5 and 60 degrees C. The study also identified potential DMSO reductase subunits and discussed their function and the proposed electron transport chain involving DMSO as the final electron acceptor.
ENVIRONMENTAL MICROBIOLOGY
(2022)
Article
Microbiology
Josephine Joy Hubloher, Lisa van der Sande, Volker Mueller
Summary: This study focused on the importance of Na+ homeostasis in Acinetobacter baumannii. Inactivation of the Mrp antiporter resulted in increased sensitivity to pH, Na+, and Li+, as well as energetic defects and impaired motility and survival under anoxic and dry conditions.
ENVIRONMENTAL MICROBIOLOGY
(2022)
Article
Microbiology
Raphael Trischler, Jennifer Roth, Matthew T. Sorbara, Xenia Schlegel, Volker Mueller
Summary: Species of the genus Blautia are beneficial gut microbes but their role in the gut microbiome and metabolic features are poorly understood. This study found that two relatives, Blautia luti and Blautia wexlerae, cannot grow on H-2 + CO2, but can perform acetogenesis through HCOOH + CO2 + CO. The lack of formate dehydrogenase and hydrogenase genes suggests that formate may be a more common interspecies carrier in the gut microbiome.
ENVIRONMENTAL MICROBIOLOGY
(2022)
Article
Multidisciplinary Sciences
Heng-Keat Tam, Patricia Konig, Stephanie Himpich, Ngoc Dinh Ngu, Rupert Abele, Volker Muller, Klaas M. Pos
Summary: This study reports the structural characteristics of AbMtlD and its role and mechanism in mannitol production. Salt-induced dimerization of AbMtlD increases its catalytic efficiency, resulting in unidirectional catalysis of mannitol production. These findings are important for understanding the survival mechanism of A. baumannii in low water activity environments.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Biochemistry & Molecular Biology
Alexander Katsyv, Volker Mueller
Summary: In this study, it was demonstrated that the energy-converting hydrogenase can reduce protons to produce molecular H-2 by translocating protons across the cell membrane. The purified enzyme showed full retention of its subunits and physiological activities.
JOURNAL OF BIOLOGICAL CHEMISTRY
(2022)
Article
Multidisciplinary Sciences
Helge M. Dietrich, Ricardo D. Righetto, Anuj Kumar, Wojciech Wietrzynski, Raphael Trischler, Sandra K. Schuller, Jonathan Wagner, Fabian M. Schwarz, Benjamin D. Engel, Volker Mueller, Jan M. Schuller
Summary: The structure of a filamentous enzyme, which has the potential to efficiently convert hydrogen and carbon dioxide into formic acid, has been revealed. This enzyme has gained interest in hydrogen storage and capturing atmospheric CO2 for combating climate change. The study shows that filamentation and rapid electron transfer enhance the activity of the enzyme. Additionally, cryo-electron tomography reveals the supramolecular organization of the enzyme in cells, which may further enhance its stability and connectivity. These findings provide insights into the function and applications of filamentous enzymes.
Article
Biology
Kanwal Kayastha, Alexander Katsyv, Christina Himmrich, Sonja Welsch, Jan M. Schuller, Ulrich Ermler, Volker Mueller
Summary: Lactate oxidation is an energetically demanding process, but some anaerobic bacteria use flavin-based electron bifurcation/confurcation (FBEB/FBEC) to overcome this energetic hurdle. The (Ldh-EtfAB)2 complex of Acetobacterium woodii, characterized by cryo-microscopy, reveals a mobile EtfAB shuttle domain between the rigid Ldh and peripheral EtfAB base units. The FADs of Ldh and the EtfAB shuttle domain interact to form the D state, while a plausible B state allows electron transfer between the EtfAB base and shuttle FADs. NAD(+) binding site correlates with the D-to-B-state transition, and kinetic analysis suggests a rotation of the EtfAB shuttle domain. Truncation of the ferredoxin domain of EtfA results in FBEC inactivity, supporting its role as a redox relay. A comprehensive catalytic mechanism of the FBEC process is proposed based on the catalytic base His423 and a metal center in Ldh.
Article
Biochemistry & Molecular Biology
Alexander Katsyv, Melanie Essig, Giada Bedendi, Selmihan Sahin, Ross D. Milton, Volker Mueller
Summary: A study found that ferredoxin plays a major role in energy and carbon metabolism in the acetogenic model organism Thermoanaerobacter kivui. The researchers cloned and purified four putative ferredoxin-like proteins, and confirmed TKV_c09620 and TKV_c16450 as ferredoxins involved in autotrophic and heterotrophic metabolism of T. kivui.
Article
Ecology
Jimyung Moon, Anja Schubert, Lara M. Waschinger, Volker Mueller
Summary: Methyl groups in anoxic environments can be used as carbon and energy sources by microorganisms through oxidation to CO2 and electron transfer to an acceptor. This study describes the generation of a mutant acetogen that stops methyl group oxidation at the formate level and reoxidizes reduced electron carriers by CO2 reduction to acetate. The mutant can grow on glycine betaine as a methyl group donor and produce formate alongside acetate. This genetic reprogramming of an acetogen into a formatogen has implications for both biotechnology and the mechanism of electron transfer in anoxic environments.
Article
Chemistry, Multidisciplinary
Alexander. Katsyv, Anuj Kumar, Patricia Saura, Maximilian C. Poverlein, Sven A. Freibert, Sven T. Stripp, Surbhi Jain, Ana P. Gamiz-Hernandez, Ville R. I. Kaila, Volker Mueller, Jan M. Schuller
Summary: Electron bifurcation is a fundamental energy coupling mechanism used by microorganisms in anoxic conditions to reduce CO2 using hydrogen. The enzyme responsible for these reactions, HydABC, uses a single flavin mononucleotide (FMN) cofactor to transfer electrons to NAD(P)+ and low-potential ferredoxins (Fd), and switches between NAD(P)+ reduction and Fd reduction modes. Understanding the mechanistic principles of electron-bifurcating hydrogenases can provide insight into energy conversion processes in microorganisms.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Biotechnology & Applied Microbiology
Josephine Joy Hubloher, Lisa Van der Sande, Christoph Schaudinn, Volker Mueller, Beate Averhoff
Summary: Acinetobacter baumannii is a multidrug-resistant opportunistic pathogen that poses a significant threat to healthcare institutions. The Tol-Pal system plays a crucial role in cell morphology, antibiotic resistance, and virulence of A. baumannii.
INTERNATIONAL MICROBIOLOGY
(2023)