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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Fast growth and high-titer bioproduction from renewable formate via metal-dependent formate dehydrogenase in Escherichia coli

Microbial bioproduction using one-carbon (C1) feedstocks has the potential to decarbonize the manufacturing of materials, fuels, and chemicals. Formate is a promising C1 feedstock, and the realization of industrial, formatotrophic platform organisms is a key goal for C1-based bioproduction. So far, a major limitation for synthetic formatotrophy has been slow energy supply due to slow formate dehydrogenase activity. Here, we implement a fast, metal-dependent formate dehydrogenase complex in a synthetic formatotrophic Escherichia coli utilizing the reductive glycine pathway. After a short-term evolution, we demonstrate formatotrophic growth of E. coli with a doubling time of less than 4.5 h, comparable to the fastest natural formatotrophs. To further explore the potential of a formate-based bioeconomy, this strain is engineered to produce mevalonate, as well as the terpenoid and aviation fuel precursor isoprenol, using formate we generate directly from the electrochemical reduction of CO2. This work demonstrates an improvement in bioproduct titer from formate, achieving the production of 3.8 g/L of mevalonate. Additionally, the abundant and recalcitrant polymer lignin is chemically decomposed into a formate-rich mixture of small organic acids and subsequently bioconverted into mevalonate. Overall, the described fast-growing, formatotrophic bioproduction strain demonstrates that a sustainable formate bioeconomy is within reach.

Cowan, Aidan E↗
NASA NTRS2017

Energy in a Planetary Context

The potential present day habitability of solar system bodies beyond Earth is limited to subsurface environments, where the availability of energy in biologically useful form is a paramount consideration. Energy availability is commonly quantified in terms of molar Gibbs energy changes for metabolisms of interest, but this can provide an incomplete and even misleading picture. A second aspect of life's requirement for energy - the rate of delivery, or power - strongly influences habitability, biomass abundance, growth rates, and, ultimately, rates of evolution. We are developing an approach to quantify metabolic power, using a cell-scale reactive transport model in which physical and chemical environmental parameters are varied. Simultaneously, we evaluate cell-specific energy flux requirements and their dependence on environmental "extremes". Comparison of metabolic power supply and demand provides a constraint on how biomass abundance varies across a range of environmental parameters, and thereby a prediction of the relative habitability of different environments. We are evaluating the predictive capability of this approach through comparison to observed distributions of microbial abundance in a range of subsurface (predominantly serpentinizing) systems.

MARINE GEOMICROBIOLOGY↗
DOE OSTI2019

Symbiotic Plant Biomass Decomposition in Fungus-Growing Termites

Termites are among the most successful animal groups, accomplishing nutrient acquisition through long-term associations and enzyme provisioning from microbial symbionts. Fungus farming has evolved only once in a single termite sub-family: Macrotermitinae. This sub-family has become a dominant decomposer in the Old World; through enzymatic contributions from insects, fungi, and bacteria, managed in an intricate decomposition pathway, the termites obtain near-complete utilisation of essentially any plant substrate. Here we review recent insights into our understanding of the process of plant biomass decomposition in fungus-growing termites. To this end, we outline research avenues that we believe can help shed light on how evolution has shaped the optimisation of plant-biomass decomposition in this complex multipartite symbiosis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Drought increases microbial allocation to stress tolerance but with few tradeoffs among community-level traits

We leverage the Kellogg Biological Station Long Term Ecological Research Main Cropping System Experiment (KBS MCSE) field experiment to test trade-offs among high growth yield (Y), resource acquisition (A), and stress tolerance (S) traits using metagenomic data from plots with different land use, drought manipulation, and C addition.

Jones, Jennifer M. [WK Kellogg Biological Station,↗
DOE OSTI2024

Bridging 20 Years of Soil Organic Matter Frameworks: Empirical Support, Model Representation, and Next Steps

Abstract In the past few decades, there has been an evolution in our understanding of soil organic matter (SOM) dynamics from one of inherent biochemical recalcitrance to one deriving from plant‐microbe‐mineral interactions. This shift in understanding has been driven, in part, by influential conceptual frameworks which put forth hypotheses about SOM dynamics. Here, we summarize several focal conceptual frameworks and derive from them six controls related to SOM formation, (de)stabilization, and loss. These include: (a) physical inaccessibility; (b) organo‐mineral and ‐metal stabilization; (c) biodegradability of plant inputs; (d) abiotic environmental factors; (e) biochemical reactivity and diversity; and (f) microbial physiology and morphology. We then review the empirical evidence for these controls, their model representation, and outstanding knowledge gaps. We find relatively strong empirical support and model representation of abiotic environmental factors but disparities between data and models for biochemical reactivity and diversity, organo‐mineral and ‐metal stabilization, and biodegradability of plant inputs, particularly with respect to SOM destabilization for the latter two controls. More empirical research on physical inaccessibility and microbial physiology and morphology is needed to deepen our understanding of these critical SOM controls and improve their model representation. The SOM controls are highly interactive and also present some inconsistencies which may be reconciled by considering methodological limitations or temporal and spatial variation. Future conceptual frameworks must simultaneously refine our understanding of these six SOM controls at various spatial and temporal scales and within a hierarchical structure, while incorporating emerging insights. This will advance our ability to accurately predict SOM dynamics.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Forward Photodynamics of the Noncanonical Red/Green NpR3784 Cyanobacteriochrome from Nostoc punctiforme

Cyanobacteriochromes (CBCRs) make up a diverse family of cyanobacterial photoreceptors distantly related to the phytochrome photoreceptors of land plants. At least two lineages of CBCRs have reacquired red-absorbing dark states similar to the phytochrome Pr resting state but are coupled to green-absorbing light-adapted states rather than the canonical far-red-absorbing light-adapted state. One such lineage includes the canonical red/green (R/G) CBCRs that includes AnPixJg2 (UniProtKB Q8YXY7) and NpR6012g4 (UniProtKB B2IU14) that have been extensively characterized. Here we examine the forward Pr photodynamics of NpR3784 (UniProtKB B2J457), a representative member of the second R/G CBCR subfamily. Using broadband transient absorption pump–probe spectroscopy, we characterize both primary (100 fs to 10 ns) and secondary (10 ns to 1 ms) forward (P r → P g ) photodynamics and compare the results to temperature-jump cryokinetics measurements. Our studies show that primary isomerization dynamics occur on an ~10 ps timescale, yet remarkably, the red-shifted primary Lumi-Rf photoproduct found in all photoactive canonical R/G CBCRs examined to date is extremely short-lived in NpR3784. Furthermore, these results demonstrate that differences in reaction pathways reflect the evolutionary history of R/G CBCRs despite the convergent evolution of their photocycle end products.

*Light↗
DOE OSTI2021

Pre-Cambrian roots of novel Antarctic cryptoendolithic bacterial lineages

Cryptoendolithic communities are microbial ecosystems dwelling inside porous rocks that are able to persist at the edge of the biological potential for life in the ice-free areas of the Antarctic desert. These regions include the McMurdo Dry Valleys, often accounted as the closest terrestrial counterpart of the Martian environment and thought to be devoid of life until the discovery of these cryptic life-forms. Despite their interest as a model for the early colonization by living organisms of terrestrial ecosystems and for adaptation to extreme conditions of stress, little is known about the evolution, diversity, and genetic makeup of bacterial species that reside in these environments. Using the Illumina Novaseq platform, we generated the first metagenomes from rocks collected in Continental Antarctica over a distance of about 350 km along an altitudinal transect from 834 up to 3100 m above sea level (a.s.l.). A total of 497 draft bacterial genome sequences were assembled and clustered into 269 candidate species that lack a representative genome in public databases. Actinobacteria represent the most abundant phylum, followed by Chloroflexi and Proteobacteria. The “Candidatus Jiangella antarctica” has been recorded across all samples, suggesting a high adaptation and specialization of this species to the harshest Antarctic desert environment. The majority of these new species belong to monophyletic bacterial clades that diverged from related taxa in a range from 1.2 billion to 410 Ma and are functionally distinct from known related taxa. Our findings significantly increase the repertoire of genomic data for several taxa and, to date, represent the first example of bacterial genomes recovered from endolithic communities. Their ancient origin seems to not be related to the geological history of the continent, rather they may represent evolutionary remnants of pristine clades that evolved across the Tonian glaciation. These unique genomic resources will underpin future studies on the structure, evolution, and function of these ecosystems at the edge of life.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

High-Throughput Functional Genomics for Energy Production

Functional genomics remains a foundational field for establishing genotype-phenotype relationships that enable strain engineering. High-throughput (HTP) methods accelerate the Design-Build-Test-Learn cycle that currently drives synthetic biology towards a forward engineering future. Trackable mutagenesis techniques including transposon insertion sequencing and CRISPR-Cas-mediated genome editing allow for rapid fitness profiling of a collection, or library, of mutants to discover beneficial mutations. Due to the relative speed of these experiments compared to adaptive evolution experiments, iterative rounds of mutagenesis can be implemented for next-generation metabolic engineering efforts to design complex production and tolerance phenotypes. Further, the expansion of these mutagenesis techniques to novel bacteria are opening up industrial microbes that show promise for establishing a bio-based economy.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1999

Post-Viking microbiology: new approaches, new data, new insights

In the 20 years since the Viking experiments, major advances have been made in the areas of microbial systematics, microbial metabolism, microbial survival capacity, and the definition of environments on earth, suggesting that life is more versatile and tenacious than was previously appreciated. Almost all niches on earth which have available energy, and which are compatible with the chemistry of carbon-carbon bonds, are known to be inhabited by bacteria. The oldest known bacteria on earth apparently evolved soon after the formation of the planet, and are heat loving, hydrogen and/or sulfur metabolizing forms. Among the two microbial domains (kingdoms) is a great deal of metabolic diversity, with members of these forms being able to grow on almost any known energy source, organic or inorganic, and to utilize an impressive array of electron acceptors for anaerobic respiration. Both hydrothermal environments and the deep subsurface environments have been shown to support large populations of bacteria, growing on energy supplied by geothermal energy, thus isolating these ecosystems from the rest of the global biogeochemical cycles. This knowledge, coupled with new insights into the history of the solar system, allow one to speculate on possible evolution and survival of life forms on Mars.

Review↗
DOE OSTI2023

Giant Virus Infection Signatures Are Modulated by Euphotic Zone Depth Strata and Iron Regimes of the Subantarctic Southern Ocean

Viruses can alter the abundance, evolution, and metabolism of microorganisms in the ocean, playing a key role in water column biogeochemistry and global carbon cycles. Large efforts to measure the contribution of eukaryotic microorganisms (e.g., protists) to the marine food web have been made, yet the in situ activities of the ecologically relevant viruses that infect these organisms are not well characterized. Viruses within the phylum Nucleocytoviricota (“giant viruses”) are known to infect a diverse range of ecologically relevant marine protists, yet how these viruses are influenced by environmental conditions remains under-characterized. By employing metatranscriptomic analyses of in situ microbial communities along a temporal and depthresolved gradient, we describe the diversity of giant viruses at the Southern Ocean Time Series (SOTS), a site within the subpolar Southern Ocean. Using a phylogeny-guided taxonomic assessment of detected giant virus genomes and metagenome-assembled genomes, we observed depth-dependent structuring of divergent giant virus families mirroring dynamic physicochemical gradients in the stratified euphotic zone. Analyses of transcribed metabolic genes from giant viruses suggest viral metabolic reprogramming of hosts from the surface to a 200-m depth. Lastly, using on-deck incubations reflecting a gradient of iron availability, we show that modulating iron regimes influences the activity of giant viruses in the field. Specifically, we show enhanced infection signatures of giant viruses under both iron-replete and iron-limited conditions. Collectively, these results expand our understanding of how the water column’s vertical biogeography and chemical surroundings affect an important group of viruses within the Southern Ocean

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1998

A natural species concept for prokaryotes

Direct molecular analyses of natural microbial populations reveal patterns that should compel microbiologists to adopt a more natural species concept that has been known to biologists for decades. The species debate can be exploited to address a larger issue - microbiologists need, in general, to take a more natural view of the organisms they study.

Review↗
DOE OSTI2020

Social Evolution and Cheating in Plant Pathogens

Plant pathogens are a critical component of the microbiome that exist as populations undergoing ecological and evolutionary processes within their host. Many aspects of virulence rely on social interactions mediated through multiple forms of public goods, including quorum-sensing signals, exoenzymes, and effectors. Virulence and disease progression involve life-history decisions that have social implications with large effects on both host and microbe fitness, such as the timing of key transitions. Considering the molecular basis of sequential stages of plant–pathogen interactions highlights many opportunities for pathogens to cheat, and there is evidence for ample variation in virulence. Case studies reveal systems where cheating has been demonstrated and others where it is likely occurring. Harnessing the social interactions of pathogens, along with leveraging novel sensing and -omics technologies to understand microbial fitness in the field, will enable us to better manage plant microbiomes in the interest of plant health.

Plant Sciences↗
DOE OSTI2022

Microbial maintenance energy quantified and modeled with microcalorimetry

Refining the energetic costs of cellular maintenance is essential for predicting microbial growth and survival in the environment. In this work, we evaluate a simple batch culture method to quantify energy partitioning between growth and maintenance using microcalorimetry and thermodynamic modeling. The constants derived from the batch culture system were comparable to those that have been reported from meta-analyses of data derived from chemostat studies. The model accurately predicted temperature-dependent biomass yield and the upper temperature limit of growth for Desulfovibrio alaskensis G20, suggesting the method may have broad application. An Arrhenius temperature dependence for the specific energy consumption rate, inferred from substrate consumption and heat evolution, was observed over the entire viable temperature range. By combining this relationship for specific energy consumption rates and observed specific growth rates, the model describes an increase in nongrowth associated maintenance at higher temperatures and the corresponding decrease in energy available for growth. This analytical and thermodynamic formulation suggests that simply monitoring heat evolution in batch culture could be a useful complement to the recognized limitations of estimating maintenance using extrapolation to zero growth in chemostats.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1991

A model for diurnal patterns of carbon fixation in a Precambrian microbial mat based on a modern analog

Microbial mat communities are one of the first and most prevalent biological communities known from the Precambrian fossil record. These fossil mat communities are found as laminated sedimentary rock structures called stromatolites. Using a modern microbial mat as an analog for Precambrian stromatolites, a study of carbon fixation during a diurnal cycle under ambient conditions was undertaken. The rate of carbon fixation depends primarily on the availability of light (consistent with photosynthetic carbon fixation) and inorganic carbon, and not nitrogen or phosphorus. Atmospheric PCO2 is thought to have decreased from 10 bars at 4 Ga (10(9) years before present) to approximately 10(-4) bars today, implying a change in the availability of inorganic carbon for carbon fixation. Experimental manipulation of levels of inorganic carbon to levels that may have been available to Precambrian mat communities resulted in increased levels of carbon fixation during daylight hours. Combining these data with models of daylength during the Precambrian, models are derived for diurnal patterns of photosynthetic carbon fixation in a Precambrian microbial mat community. The models suggest that, even in the face of shorter daylengths during the Precambrian, total daily carbon fixation has been declining over geological time, with most of the decrease having occurred during the Precambrian.

Review↗
DOE OSTI2019

High-resolution lineage tracking reveals travelling wave of adaptation in laboratory yeast

In rapidly adapting asexual populations, including many microbial pathogens and viruses, numerous mutant lineages often compete for dominance within the population. These complex evolutionary dynamics determine the outcomes of adaptation, but have been difficult to observe directly. Previous studies have used whole-genome sequencing to follow molecular adaptation; however, these methods have limited resolution in microbial populations. Here we introduce a renewable barcoding system to observe evolutionary dynamics at high resolution in laboratory budding yeast. We find nested patterns of interference and hitchhiking even at low frequencies. These events are driven by the continuous appearance of new mutations that modify the fates of existing lineages before they reach substantial frequencies. We observe how the distribution of fitness within the population changes over time, and find a travelling wave of adaptation that has been predicted by theory. We show that clonal competition creates a dynamical ‘rich-get-richer’ effect: fitness advantages that are acquired early in evolution drive clonal expansions, which increase the chances of acquiring future mutations. However, less-fit lineages also routinely leapfrog over strains of higher fitness. Finally, our results demonstrate that this combination of factors, which is not accounted for in existing models of evolutionary dynamics, is critical in determining the rate, predictability and molecular basis of adaptation.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1982

Microbial ecology of extreme environments: Antarctic dry valley yeasts and growth in substrate-limited habitats

The success of the Antarctic Dry Valley yeasts presumeably results from adaptations to multiple stresses, to low temperatures and substrate-limitation as well as prolonged resting periods enforced by low water availability. Previous investigations have suggested that the crucial stress is substrate limitation. Specific adaptations may be pinpointed by comparing the physiology of the Cryptococcus vishniacii complex, the yeasts of the Tyrol Valley, with their congeners from other habitats. Progress was made in methods of isolation and definition of ecological niches, in the design of experiments in competition for limited substrate, and in establishing the relationships of the Cryptococcus vishniacii complex with other yeasts. In the course of investigating relationships, a new method for 25SrRNA homology was developed. For the first time it appears that 25SrRNA homology may reflect parallel or convergent evolution.

Vishniac, H. S.↗
NASA NTRS2019

Evolved Gas Analyses of Sedimentary Rocks and Eolian Sediment in Gale Crater, Mars: Results of the Curiosity Rover's Sample Analysis at Mars Instrument.

The Sample Analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, SO2, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. The SAM-EGA heats samples to 870°C and measures evolved gas releases as function of temperature. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. CO2 and CO evolved at similar temperatures suggesting that as much as 2373 ± 820 μgC/g may occur as organic carbon in the Gale Crater rock record while relatively higher temperature CO2 detections are consistent with carbonate (<0.70 ± 0.1 wt % CO3). Evolved NO amounts up to 0.06 ± 0.03 wt % NO3 have been detected while O2 detections suggests chlorates and/or perchlorates (0.05 to 1.05 wt % ClO4) are present. Evolution of SO2 indicated the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 - 2.5 wt% H2O) was consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2S detections suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.

Sutter, Brad↗
NASA NTRS2017

Evolved Gas Analyses of Sedimentary Rocks and Eolian Sediment in Gale Crater, Mars: Results of the Curiosity Rover's Sample Analysis at Mars Instrument from Yellowknife Bay to the Namib Dune

The sample analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2 (160 +/- 248-2373 +/- 820 μgC(CO2)/g) and CO (11 +/- 3-320 +/- 130 μgC(CO)/g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO2 at temperatures consistent with carbonate (0.32 +/- 0.05-0.70 +/- 0.1 wt % CO3). Evolved NO amounts to 0.002 +/- 0.007-0.06 +/- 0.03 wt % NO3. Evolution of O2 suggests that oxychlorine phases (chlorate/perchlorate) (0.05 +/- 0.025-1.05 +/- 0.44 wt % ClO4) are present, while SO2 evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 +/- 0.3-2.5 +/- 1.6 wt % H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2 and H2S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.

Sutter, B.↗