Apr 01, 2021

Advisory Board and Contents

Scientific Life

Engineering Biocatalytic Solar Fuel Production: The PHOTOFUEL Consortium
• Julian Wichmann,
• Kyle J. Lauersen,
• Natascia Biondi,
• Magnus Christensen,
• Tiago Guerra,
• Klaus Hellgardt,
• Simon Kühner,
• Markku Kuronen,
• Pia Lindberg,
• Christine Rösch,
• Ian S. Yunus,
• Patrik Jones,
• Peter Lindblad,
• Olaf Kruse
The EU Horizon2020 consortium PHOTOFUEL joined academic and industrial partners from biology, chemistry, engineering, engine design, and lifecycle assessment, making tremendous progress towards engine-ready fuels from CO₂ via engineered photosynthetic microbes. Technical, environmental, economic, and societal opportunities and challenges were explored to frame future technology realization at scale.

Spotlights

Reductive Glycine Pathway: A Versatile Route for One-Carbon Biotech
• Nico J. Claassens
Hong et al. heterologously expressed the metabolic core of the reductive glycine pathway (rGlyP) as a sink for the anaerobic conversion of glycerol. This recent study concludes several reports in 2020 on the ATP-efficient, one-carbon-assimilating rGlyP. Its engineering in diverse hosts could help the transformation toward renewable, one-carbon-based bioproduction.

Directed Evolution of Propionyl-CoA Carboxylase for Succinate Biosynthesis
• Yuwan Liu,
• Huifeng Jiang
Due to low carboxylase activity, CO₂ biotransformation is challenging to achieve using natural CO₂ fixation pathways. Liu et al. have improved the activity of propionyl-CoA carboxylase (PCC) 94-fold, enabling the efficient synthesis of succinate from acetyl-CoA and paving the way for CO₂ assimilation via the 3-hydroxypropionate (3-HP) bicycle or 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) cycle.

Forum

Promoting Lignin Valorization by Coping with Toxic C1 Byproducts
• Zhihui Zhang,
• Yu Wang,
• Ping Zheng,
• Jibin Sun
The toxic C1 compounds methanol and formaldehyde are generated during bioconversion of lignin into value-added chemicals. These toxins can be detoxified and assimilated by methylotrophs to synthesize useful metabolites and cell biomass. We discuss the promising future of constructing integrated biosystems to use toxic C1 byproducts and promote lignin valorization.

Opinions

In situ Biogas Upgrading by CO₂-to-CH₄ Bioconversion
• Shanfei Fu,
• Irini Angelidaki,
• Yifeng Zhang
Biogas produced by anaerobic digestion is an important renewable energy carrier. Nevertheless, the high CO₂ content in biogas limits its utilization to mainly heat and electricity generation. Upgrading biogas into biomethane broadens its potential as a vehicle fuel or substitute for natural gas. CO₂-to-CH₄ bioconversion represents one cutting-edge solution for biogas upgrading. In situ bioconversion can capture endogenous CO₂ directly from the biogas reactor, is easy to operate, and provides an infrastructure for renewable electricity storage.

Synthetic Methylotrophy in Yeasts: Towards a Circular Bioeconomy
• Jonathan Thomas Fabarius,
• Vanessa Wegat,
• Arne Roth,
• Volker Sieber
Mitigating climate change is a key driver for the development of sustainable and CO₂-neutral production processes. In this regard, connecting carbon capture and utilization processes to derive microbial C₁ fermentation substrates from CO₂ is highly promising. This strategy uses methylotrophic microbes to unlock next-generation processes, converting CO₂-derived methanol. Synthetic biology approaches in particular can empower synthetic methylotrophs to produce a variety of commodity chemicals. We believe that yeasts have outstanding potential for this purpose, because they are able to separate toxic intermediates and metabolic reactions in organelles.

Microbial Electrosynthesis: Where Do We Go from Here?
• Ludovic Jourdin,
• Thomas Burdyny
Open Access
The valorization of CO₂ to valuable products via microbial electrosynthesis (MES) is a technology transcending the disciplines of microbiology, (electro)chemistry, and engineering, bringing opportunities and challenges. As the field looks to the future, further emphasis is expected to be placed on engineering efficient reactors for biocatalysts, to thrive and overcome factors which may be limiting performance. Meanwhile, ample opportunities exist to take the lessons learned in traditional and adjacent electrochemical fields to shortcut learning curves.

Production of Bio-alkanes from Biomass and CO₂
• Richen Lin,
• Chen Deng,
• Wuyuan Zhang,
• Frank Hollmann,
• Jerry D. Murphy
Bioelectrochemical technologies such as electro-fermentation and microbial CO₂ electrosynthesis are emerging interdisciplinary technologies that can produce renewable fuels and chemicals (such as carboxylic acids). The benefits of electrically driven bioprocesses include improved production rate, selectivity, and carbon conversion efficiency. However, the accumulation of products can lead to inhibition of biocatalysts, necessitating further effort in separating products. The recent discovery of a new photoenzyme, capable of converting carboxylic acids to bio-alkanes, has offered an opportunity for system integration, providing a promising approach for simultaneous product separation and valorisation.

Reviews

Engineered Methanotrophy: A Sustainable Solution for Methane-Based Industrial Biomanufacturing
• Anh Duc Nguyen,
• Eun Yeol Lee
Methane is a promising feedstock with high abundance and low cost for the sustainable production of biochemicals and biofuels. Methanotrophic bacteria are particularly interesting platforms for methane bioconversion as they can utilize methane as a carbon substrate. Recently, breakthroughs in the understanding of methane metabolism in methanotrophs as well as critical advances in systems metabolic engineering of methanotrophic bacteria have been reported. Here, we discuss the important gaps in the understanding of methanotrophic metabolism that have been uncovered recently and the current trends in systems metabolic engineering in both methanotrophic bacteria and non-native hosts to advance the potential of methane-based biomanufacturing.

From Acetate to Bio-Based Products: Underexploited Potential for Industrial Biotechnology
• Dirk Kiefer,
• Manuel Merkel,
• Lars Lilge,
• Marius Henkel,
• Rudolf Hausmann
Currently, most biotechnological products are based on microbial conversion of carbohydrate substrates that are predominantly generated from sugar- or starch-containing plants. However, direct competitive uses of these feedstocks in the food and feed industry represent a dilemma, so using alternative carbon sources has become increasingly important in industrial biotechnology. A promising alternative carbon source that may be generated in substantial amounts from lignocellulosic biomass and C1 gases is acetate.

Metabolic Engineering of Cupriavidus necator H16 for Sustainable Biofuels from CO₂
• Justin Panich,
• Bonnie Fong,
• Steven W. Singer
Open Access
Decelerating global warming is one of the predominant challenges of our time and will require conversion of CO₂ to usable products and commodity chemicals. Of particular interest is the production of fuels, because the transportation sector is a major source of CO₂ emissions. Here, we review recent technological advances in metabolic engineering of the hydrogen-oxidizing bacterium Cupriavidus necator H16, a chemolithotroph that naturally consumes CO₂ to generate biomass. We discuss recent successes in biofuel production using this organism, and the implementation of electrolysis/artificial photosynthesis approaches that enable growth of C.

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