Largus Theodora Angenent

University of Tuebingen | EKU Tübingen · Department of Geosciences

Industrial applications of microbial electrochemical systems will require regular maintenance shutdowns, involving inspections and component replacements to extend the lifespan of the system. Here, we examined the impact of such shutdowns on the performance of three electrode materials (i.e., platinized titanium, graphite, and nickel) as cathodes i...

Integrating hydrothermal treatment processes and anaerobic digestion (AD) is promising for maximizing resource recovery from biomass and organic waste. The process water generated during hydrothermal treatment contains high concentrations of organic matter, which can be converted into biogas using AD. However, process water also contains various co...

Here, we report the draft genome of Magnusiomyces sp. LA-1, which was isolated from a C6-C8 carboxylic acid-producing bioreactor. The draft genome of Magnusiomyces sp. LA-1 is 19,829,165 bp in length, is divided into six contigs that comprise 6,557 CDS regions, and has a GC content of 34.5%.

Medium-chain carboxylates are used in various industrial applications. These chemicals are typically extracted from palm oil, which is deemed not sustainable. Recent research has focused on microbial chain elongation using reactors to produce medium-chain carboxylates, such as n-caproate (C6) and n-caprylate (C8), from organic substrates such as wa...

Meeting a surging demand for superior micronutrient-rich protein sources and finding production practices that are less detrimental to the climate will be critical challenges of the 21 st century. New technologies are needed to decouple food production from land use. Our group previously proposed a two-stage Power-to-Protein technology to produce m...

Our societies must reconsider current industrial practices and find carbon-neutral alternatives to avoid the detrimental environmental effects that come with the release of greenhouse gases from fossil-energy carriers. Using renewable...

Lactate is among the top-ten-biobased products. It occurs naturally as D- or L-isomer and as a racemic mixture (DL-lactate). Generally, lactate with a high optical purity is more valuable. In searching for suitable renewable feedstocks for lactate production, unutilized organic waste streams are increasingly coming into focus. Here, we investigated...

Methanogenesis allows methanogenic archaea to generate cellular energy for their growth while producing methane. Thermophilic hydrogenotrophic species of the genus Methanothermobacter have been recognized as robust biocatalysts for a circular carbon economy and are already applied in power-to-gas technology with biomethanation, which is a platform...

Microbial electrosynthesis is an emerging biosynthesis technology that produces value-added chemicals and fuels and, at the same time, reduces the environmental carbon footprint. However, constraints, such as low current densities...

This study is a continuation by the Environmental Biotechnology Group of the University of Tübingen in memoriam to Reinhard Wirth, who initiated the work on Mth60 fimbriae at the University of Regensburg. Growth in biofilms or biofilm-like structures is the prevailing lifestyle for most microbes in nature. The first crucial step to initiate biofilm...

Methanothermobacter has been pivotal in elucidating the biochemistry of hydrogenotrophic methanogenesis. These microbes generate cellular energy to grow by producing methane from hydrogen and carbon dioxide. Recently, this physiological trait was adopted for biotechnology in power-to-gas processes to store renewable electric energy in form of metha...

Methanogenesis allows methanogenic archaea (methanogens) to generate cellular energy for their growth while producing methane. Hydrogenotrophic methanogens thrive on carbon dioxide and molecular hydrogen as sole carbon and energy sources. Thermophilic and hydrogenotrophic Methanothermobacter spp. have been recognized as robust biocatalysts for a ci...

Recycling waste gases from industry is vital for the transition toward a circular economy. The model microbe Clostridium ljungdahlii reduces carbon from syngas and primarily produces acetate and ethanol. Here, a gas fermentation experiment is presented in chemostats with C. ljungdahlii and pure carbon monoxide (CO) as feedstock while entirely omitt...

Methanogenic archaea of the order Methanobacteriales are widespread in anaerobic environments and play pivotal roles in microbial communities. The family of Methanobacteriaceae encompasses mesophilic and thermophilic hydrogenotrophic species. Mesophilic species are found in various natural and anthropogenic environments (e.g., are associated with t...

Microbial electrosynthesis is an emerging biosynthesis technology that produces value-added chemicals and fuels and, at the same time, reduces the environmental carbon footprint. However, constraints, such as low current densities and high inner resistance, disfavor this technology for industrial-scale purposes. The cathode performance has been str...

Current food production practices contribute significantly to climate change. To transition into a sustainable future, a combination of new food habits and a radical food production innovation must occur. Single-cell protein from microbial fermentation can profoundly impact sustainability. This review paper explores opportunities offered by gas fer...

This study was continued by the Environmental Biotechnology Group of the University of Tübingen in memoriam to Reinhard Wirth, who initiated the work on Mth60 fimbriae at the University of Regensburg. Growth in biofilms or biofilm-like structures is the prevailing lifestyle for most microbes in nature. The first step to initiate biofilms is the adh...

For Clostridium ljungdahlii, the RNF complex plays a key role for energy conversion from gaseous substrates such as hydrogen and carbon dioxide. In a previous study, a disruption of RNF-complex genes led to the loss of autotrophy, while heterotrophy was still possible via glycolysis. Furthermore, it was shown that the energy limitation during autot...

The pH is a critical parameter in chain-elongating bioreactors, affecting: (1) the concentration of inhibitory undissociated carboxylic acids, which in turn affects the efficiency of product extraction; (2) the thermodynamics; and (3) the kinetics. Here, we examined the effect of five different pH levels (5.5 to 7.0) on n-caprylate (C8) production...

The pH is a critical parameter in chain-elongating bioreactors, affecting: (1) the concentration of inhibitory undissociated carboxylic acids, which in turn affects the efficiency of product extraction; (2) the thermodynamics; and (3) the kinetics. Here, we examined the effect of five different pH levels (5.5 to 7.0) on n-caprylate (C8) production...

Oxygen is considered detrimental to anaerobic fermentation processes by many practitioners. However, deliberate oxygen sparging has been used successfully for decades to remove H2S in anaerobic digestion (AD) systems. Moreover, microaeration techniques during AD have shown that small doses of oxygen may enhance process performance and promote the i...

Throughout history, the first and foremost role of urban water management has been the protection of human health and the local aquatic environment. To this end, the practice of (waste-)water treatment has maintained a central focus on the removal of pollutants through dissipative pathways. Approaches like – in the case of wastewater treatment – th...

Wastewater composition directly impacts its anaerobic biodegradability, affecting methane production rates, the concentration of effluent products, and ultimately, the overall energy output and treatment efficiency of the anaerobic digestion system....

The world economies are facing permanently increasing energy demands. At the same time, carbon emissions from fossil sources need to be circumvented to minimize harmful effects from climate change.

Biochar can participate in biogeochemical electron transfer processes due to its electron-accepting and donating capabilities (i.e., geobattery) and electron conductivity (i.e., geoconductor). These two functions were separately demonstrated to play a role in biogeochemical iron cycling and methane formation. Yet, little is known about the coupled...

Weatherization of residential homes is a widespread procedure to retrofit older homes to improve the energy efficiency by reducing building leakage. Several studies have evaluated the effect of weatherization on indoor pollutants, such as formaldehyde, radon, and indoor particulates, but few studies have evaluated the effect of weatherization on in...

Medium-chain carboxylic acids (MCCAs), which can be generated from organic waste and agro-industrial side streams through microbial chain elongation, are valuable chemicals with numerous industrial applications. Membrane-based liquid-liquid extraction (pertraction) as a downstream separation process to extract MCCAs has been applied successfully. H...

For Clostridium ljungdahlii , the RNF complex plays a key role for energy conversion from gaseous substrates such as hydrogen and carbon dioxide. In a previous study, a disruption of RNF-complex genes led to the loss of autotrophy, while heterotrophy was still possible via glycolysis. Furthermore, it was shown that the energy limitation during auto...

n-Caproate production by reactor microbiomes is receiving more attention due to its high economic and environmental benefits. However, the ecological complexity within the bioreactor obstructs the development of functional microbiome shaping technology, which is expected to further unlock the potential of microbiomes. This study adopted the “Design...

Northern peatlands are experiencing more frequent and severe fire events as a result of changing climate conditions. Recent studies show that such a fire-regime change imposes a direct climate-warming impact by emitting large amounts of carbon into the atmosphere. However, the fires also convert parts of the burnt biomass into pyrogenic carbon. Her...

Redox-driven biogeochemical element cycles play a central role in converting organic matter in aquatic ecosystems. They also perform key functions such as removing nitrate, mitigating the formation of greenhouse gases and weakening the effects of contaminants. Recent research has revealed the presence of redox-active compounds in these ecosystems w...

Thermophilic Methanothermobacter spp. are used as model microbes to study the physiology and biochemistry of the conversion of hydrogen and carbon dioxide into methane ( i.e ., hydrogenotrophic methanogenesis), because of their short doubling times and robust growth with high growth yields. Yet, a genetic system for these model microbes was missing...

Bulk production of medium-chain carboxylates (MCCs) with 6–12 carbon atoms is of great interest to biotechnology. Open cultures (e.g., reactor microbiomes) have been utilized to generate MCCs in bioreactors. When in-line MCC extraction and prevention of product inhibition is required, the bioreactors have been operated at mildly acidic pH (5.0–5.5)...

Medium-chain carboxylic acids (MCCAs) are valuable platform chemicals and can be produced from waste biomass sources or syngas fermentation effluent through microbial chain elongation. We have previously demonstrated successful approaches to separate >90% purity oil with different MCCAs (MCCA oil) by integrating the anaerobic bioprocess with membra...

Contribution to the International Chain Elongation Conference 2020 | ICEC 2020

Microbial chain elongation enables the conversion of organic wastes and agroindustrial sidestreams into medium chain carboxylic acids (MCCAs), with application in the production of plasticizers, personal care products, functional feed additives, and fuels. This work describes the up-scaling of the production of MCCAs from thin stillage, and their s...

Many governments and institutions are advocating for higher renewable energy deployment to lower their carbon footprint and mitigate the effects of climate change. Cornell University instituted the “climate action plan” to achieve carbon neutrality, of which geothermal heat extracted from deep rocks (Earth source heat) is a critical component. This...

The natural world blends microenvironments to create a continuum of spatial niches wherein microbial consortia participate in metabolic exchanges. The capability with which nature selects a consortium to complement a given niche is often taken for granted. Not by Shahab et al. (2020), however, who created a synthetic microbial consortium to mediate...

In the U.S., several states have attempted to mitigate greenhouse-gas emissions by banning food wastes from landfills. As a result, U.S.-based companies are now providing decentralized food-waste management systems for supermarkets and restaurants, which include storage as a slurry. It is unclear, however, which storage conditions (factors) would a...

The mechanism of long-distance electron transfer via redox-active particulate natural organic matter (NOM) is still unclear, especially considering its aggregated nature and the resulting low diffusivity of its quinone- and hydroquinone-containing molecules. Here we conducted microbial iron(III)-mineral reduction experiments in which anthraquinone-...

Medium-chain carboxylic acids (MCCAs) are valuable platform chemicals with numerous industrial-scale applications. These MCCAs can be produced from waste biomass sources or syngas fermentation effluent through an anaerobic fermentation process called chain elongation. We have previously demonstrated successful approaches to separate >90%-purity oil...

Background Bulk production of medium-chain carboxylates (MCCs) with 6-12 carbon atoms is of great interest to biotechnology. Open cultures ( e . g ., reactor microbiomes) have been utilized to generate MCCs in bioreactors. When in-line MCC extraction and prevention of product inhibition is required, the bioreactors have been operated at mildly acid...

This study highlights the potential of combining energy and dairy waste management systems to maximize resource recovery and reduce dairy farming environmental impacts. A combined anaerobic digestion, hydrothermal liquefaction, and a biomethanation process system was used to generate Renewable Natural Gas (RNG). The biomethanation step is part of a...

Acetogenic bacteria are rising in popularity as chassis microbes in biotechnology due to their capability of converting inorganic one-carbon (C1) gases to organic chemicals. To fully uncover the potential of acetogenic bacteria, synthetic-biology tools are imperative to either engineer designed functions or to interrogate the physiology. Here, we r...

BACKGROUND The high rate production of n‐caproic acid (C6) through chain elongation can be achieved with the use of pertraction systems for the continuous and selective extraction of C6. However, although the biological conversion processes are enhanced at a neutral pH, high extraction efficiency depends on acidic conditions. Understanding of these...

S1: Detailed substrate flow rate and composition over the 92 d of experiment duration; S2: Fermented sugarcane juice mineral composition; S3: Membrane system, determination of the mass transfer coefficient (kext) and specific superficial extraction rates (rA,ext); S4: Overview of the experimental stoichiometric conversion; S5: Implementation of the...

The pH-value in fermentation broth is a critical factor for the metabolic flux and growth behavior of acetogens. A decreasing pH level throughout time due to undissociated acetic acid accumulation is anticipated under uncontrolled pH conditions such as in bottle experiments. As a result, the impact of changes in the metabolism (e.g., due to a genet...

Akanksha Mishra is currently a PhD student at the University of Tübingen in Germany. She is working in the field of gas fermentation under the supervision of Prof. Angenent. For her thesis, she is developing the power-to-protein system by operating a two-stage bioprocessing system. She is originally from India and moved to Germany after the complet...

In several states of the U.S., one measure to mitigate greenhouse-gas emissions has been to ban food wastes from landfills. As a result, U.S.-based companies are now providing decentralized food-waste management systems for supermarkets and restaurants, which include storage as a slurry. It is unclear, however, which storage conditions (factors) wo...

Acetogenic bacteria are rising in popularity as chassis microbes in biotechnology due to their capability of converting inorganic one-carbon (C1) gases to organic chemicals. To fully uncover the potential of acetogenic bacteria, synthetic-biology tools are imperative to either engineer designed functions or to interrogate the physiology. Here, we r...

Pure (single) cultures of microorganisms and mixed microbial communities (microbiomes) have been important for centuries in providing renewable energy, clean water and food products to human society and will continue to play a crucial role to pursue the Sustainable Development Goals. To use microorganisms effectively, microbial engineered processes...

The biochemical methane potential (BMP) assay is a standard method for characterizing biomethane potential and anaerobic biodegradability organic waste streams. Therefore, the BMP protocol must be standardized to reliably compare these parameters for various substrates. Here, the effect of inoculum selection on biomethane potential was investigated...

Weatherization of residential homes is a popular retrofit procedure to improve the energy efficiency of older homes by reducing building leakage. It is a vital tool in the fight against climate change. Several studies have evaluated the effect of weatherization on indoor pollutants such as formaldehyde and radon, but few studies have evaluated the...

Redox-active organic molecules such as anthraquinone-2,6-disulfonate (AQDS) and natural organic matter (NOM) can act as electron shuttles thus facilitating electron transfer from Fe(III)-reducing bacteria (FeRB) to terminal electron acceptors such as Fe(III) minerals. In this research, we examined the length scale over which this electron shuttling...

Northern peatlands are experiencing more frequent fire events as a result of changing climate conditions. Forest fires naturally result in a direct and negative climate impact by emitting large amounts of carbon into the atmosphere. Recent studies show that this extensive emission may shift the soil carbon regime from a sink to a source. However, t...

The human gut microbiome is made of trillions of microbial cells, most of which are Bacteria , with a subset of Archaea . The bacterial family Christensenellaceae and the archaeal family Methanobacteriaceae are widespread in human guts. They correlate with each other and with a lean body type. Whether species of these two families interact and how...

The aim of this study was to evaluate the role of acetate (C2) on n-butyric (C4) and n-caproic acid (C6) production, using fermented sugarcane molasses as a substrate. Inoculum sludge was acclimatized in a continuous upflow anaerobic sludge blanket reactor, where ethanol (EtOH) and acetate (C2) were administered at a ratio of 6:1 (g COD:g COD). Org...

The pH-value in fermentation broth has a large impact on the metabolic flux and growth behavior of acetogens. A decreasing pH level throughout time due to undissociated acetic acid accumulation is anticipated under uncontrolled pH conditions such as in bottle experiment. As a result, the impact of changes in the metabolism (e.g., due to a genetic m...

Across human populations, 16S rRNA gene-based surveys of gut microbiomes have revealed that the bacterial family Christensenellacea e and the archaeal family Methanobacteriaceae co-occur and are enriched in individuals with a lean, compared to an obese, BMI. Whether these association patterns reflect interactions between metabolic partners remains...

Microbial Fe(III) reduction plays an important role for biogeochemical carbon and iron cycling in sediments and soils. Biochar is used as a soil amendment to increase fertility and lower N2O/CO2 emissions. It is redox-active and can stimulate microbial Fe(III) mineral reduction. It is currently unknown, however, how the aggregation of cells and Fe(...

Innovative, low-cost methods for inactivating pathogens in human fecal material (HFM) are needed, particularly in expanding urban areas where conventional sewer systems and centralized wastewater treatment plants are not feasible. To address this challenge, we have developed a bioprocess that utilizes open cultures of anaerobic bacteria (i.e., micr...

Ascaris eggs are commonly used as indicators for pathogen inactivation during the treatment of fecal sludge and wastewater due to their highly resistant lipid membrane and ability to survive in the envi- ronment for long periods of time. Current guidelines suggest that thermal treatment alone cannot inactivate Ascaris eggs at temperatures below 45°...

To prevent an environmental collapse while feeding a future human population of 10 billion people, dilute nitrogen in waste streams as a nitrogen source and carbon dioxide as a carbon source should be recovered and recycled into edible protein as part of the circular economy. For this to work, however, ample renewable electric power would be necess...

Syntrophic microbial partnerships are found in many environments and play critical roles in wastewater treatment, global nutrient cycles, and gut systems. An important type of syntrophy for the anaerobic conversion of carboxylic acids is H2 syntrophy. In this type of microbial partnership, dissolved H2 is produced by a bacterium and rapidly consume...

Anaerobic digestion coupled with combined heat and power production on dairy farms is environmentally advantageous; however, high capital and operating costs have limited its adoption, especially in the United States, where renewable electricity and heat production are under-incentivized. Biogas is also at a disadvantage because it has to compete w...

Syngas fermentation to ethanol and acetate has recently been coupled to microbial chain elongation to produce medium-chain carboxylates (MCCs), including n-caproate and n-caprylate. These medium chain carboxylates are relatively hydrophobic, and thus easier to extract from solution than miscible ethanol. Here, we examined the effect of eleven diffe...

A previous study had reported that the Fenton reaction at full scale increased the digestibility of thickened sludge in a digester. The authors of the study had observed a positive effect on biogas productivity, but without a control. Here, we evaluated this result by investigating the anaerobic treatment characteristics of fresh, thickened sludge...

Pyrogenic carbon contains redox-active functional groups and polyaromatic carbon matrices that are both capable of transferring electrons. Several techniques have been explored to characterize the individual electron transfer process of either functional groups or carbon matrices individually. However, simultaneous analysis of both processes remain...

Distributed, wasted, or stranded feedstocks, when converted and upgraded into fuels, could replace about 6% of the U.S. demand for liquid fuels, which is about 25% of the net import of petroleum by the United States. We review the current state of modular approaches for conversion of these feedstocks, including the technology and economics associat...

The antibiotic monensin is fed to dairy cows to increase milk production efficiency. A fraction of this monensin is excreted into the cow manure. Previous studies have found that cow manure containing monensin can negatively impact the performance of anaerobic digesters, especially upon first introduction. Few studies have examined whether the anae...

Anaerobic digestion systems on dairy farms in New York State rely on gate-fee revenues from co-digestion to ensure economic viability. Yet, because gate fees are paid on a volumetric (or weight) basis, farmers have been compelled to accept large waste volumes. When these wastes are co-digested at rates exceeding the design capacity of the digester,...

Acid whey is a Greek-yogurt waste stream and can be a resource to produce biofuel precursors. Our objective was to convert acid whey into medium-chain carboxylic acid (MCCA) oil with the open-culture carboxylate platform. Here, we developed a temperature-phased bioprocess with different anaerobic reactor microbiomes, performing thermophilic lactic...

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about mi...

The fermentation of synthesis gas (including carbon monoxide, carbon dioxide, and hydrogen) with anaerobic acetogens is an established biotechnological process that has recently been transferred to a commercial scale. The natural product spectrum of acetogens is natively restricted to acetate, ethanol, and 2,3-butanediol but is rapidly expanding to...

The cover image, by Dominic Woolf et al., is based on the In the Field An open‐source biomass pyrolysis reactor, DOI: 10.1002/bbb.1814.

Despite its long history of technological development, much charcoal production still relies on polluting and inefficient technologies utilizing traditional kiln designs. In addition to the need for improved charcoal production systems, the growing interest globally in pyrolysis of biomass to generate biochar as a soil fertility improver and for cl...

Renewable electric energy production like wind power or photovoltaics faces temporal fluctuations and spatial separation of source and sink creating the need for suitable storage and conversion technologies. Further, a...

Anaerobic digestion (AD) is a mature biotechnology-production platform with millions of installations at homes, farms, and industrial/municipal settings. Large-scale industrial, agricultural, and municipal waste-treatment systems may observe novel integration with electrochemical, biological, physical, and thermochemical process units to make AD mo...