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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Unveiling the hidden world of microorganisms and their impact on the Earth's ecosystems

Microorganisms are the unseen drivers of the Earth, impacting everything from the air we breathe to the soil beneath our feet. The roles they play in maintaining ecosystem functioning, particularly in the biogeochemical cycling of carbon, nitrogen, phosphorus, sulfur, and metals, are profound. Microbial communities are critical in mediating organic carbon mineralization, methane cycling, denitrification, and sulfate reduction, all of which regulate carbon storage and greenhouse gas emissions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Metabolic engineering of non-pathogenic microorganisms for 2,3-butanediol production

2,3-Butanediol (2,3-BDO) is a promising commodity chemical with various industrial applications. While petroleum-based chemical processes currently dominate the industrial production of 2,3-BDO, fermentation-based production of 2,3-BDO pro- vides an attractive alternative to chemical-based processes with regards to economic and environmental sustainability. The achievement of high 2,3-BDO titer, yield, and productivity in microbial fermentation is a prerequisite for the production of 2,3-BDO at large scales. Also, enantiopure production of 2,3-BDO production is desirable because 2,3-BDO stereoisomers have unique physicochemical properties. Pursuant to these goals, many metabolic engineering strategies to improve 2,3-BDO pro- duction from inexpensive sugars by Klebsiella oxytoca, Bacillus species, and Saccharomyces cerevisiae have been developed. Furthermore, this review summarizes the recent advances in metabolic engineering of non-pathogenic microorganisms to enable efficient and enantiopure production of 2,3-BDO.

2,3-BDO stereoisomers↗
DOE OSTI2026

Impact of europium and samarium on growth and metabolism of two anaerobic wastewater microorganisms: Sporacetigenium mesophilum and Clostridium sporogenes

Increases in environmental fluxes of rare earth elements (REEs) stemming from increased demand for these technology critical elements may affect microbial ecosystem functions important for pollutant degradation and nutrient cycling. Here, this study investigates the responses of Sporacetigenium mesophilum and Clostridium sporogenes, two anaerobic fermenters, to varying concentrations of two REE, namely europium and samarium. Eu and Sm are adjacent lanthanides but differ significantly in their redox behavior. We tested Eu and Sm concentrations ranging from < 1 to 600 µM. Despite the close phylogenetic relatedness of the two bacteria, we observed species-specific as well as REE-specific and incubation time-dependent sensitivities. S. mesophilum exhibited pronounced inhibition of hydrogen production and growth with exposure to ≥ 60 µM of Eu, but with 6 µM Eu, a hormetic effect was observed—hydrogen production was enhanced relative to the control. With Sm, the only impact observed on S. mesophilum was inhibition at the highest concentration (600 µM) tested. For C. sporogenes, growth inhibition was observed only at 600 µM Eu or Sm, and no hormesis was observed with either REE. This study offers both significant benefits and novelty by addressing the emerging environmental concern of REE pollution, particularly the effects of Eu and Sm on anaerobic microorganisms relevant to wastewater treatment. It provides valuable insights into REE impacts under anaerobic conditions, which are essential for understanding potential disruptions to organic matter degradation and nutrient cycling processes.

60 - APPLIED LIFE SCIENCES↗
DOE OSTI2019

High variations of methanogenic microorganisms drive full-scale anaerobic digestion process

Anaerobic digestion is one of the most successful waste management strategies worldwide, wherein microorganisms play an essential role in reducing organic pollutants and producing renewable energy. However, variations of microbial community in full-scale anaerobic digesters, particularly functional groups relevant to biogas production, remain elusive. Here, we examined microbial community in a year-long monthly time series of 3 full-scale anaerobic digesters. We observed substantial diversification in community composition, with only a few abundant OTUs (e.g. Clostridiales, Anaerolineaceae and Methanosaeta) persistently present across different samples. Similarly, there were high variations in relative abundance of methanogenic archaea and methanogenic genes, which were positively correlated (r 2 = 0.530, P < 0.00 1). Variations of methanogens explained 55.7% of biogas producing rates, much higher than the explanatory percentage of environmental parameters (16.4%). Hydrogenotrophic methanogens, especially abundant Methanomicrobiales taxa, were correlated with biogas production performance (r = 0.665, P < 0.001) and nearly all methanogenic genes (0.430 < r < 0.735, P < 0.012). Given that methanogenic archaea or genes are well established for methanogenesis, we conclude that high variations in methanogenic traits (e.g. taxa or genes) are responsible for biogas production variations in full-scale anaerobic digesters.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

Cytotoxicity of TiO{sub 2} nanoparticles towards freshwater sediment microorganisms at low exposure concentrations

There is a persistent need to assess the effects of TiO{sub 2} nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO{sub 2} nanoparticle-induced acute toxicity at sub-ppm level (≤1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. - Highlights: • Toxicity of NPs towards freshwater sediment bacteria at sub-ppm concentrations. • Decreased toxicity of the nanoparticles in the consortium of microorganisms. • Enhanced bacterial resistance through EPS and biofilm formation in the presence of NPs. • Considerable surface damage of cells and internalization of NPs. • Gene expression analyses related to biofilm formation in the presence of NPs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Research on the influence of anaerobic stabilization of various dairy sewage sludge on biodegradation of polycyclic aromatic hydrocarbons PAHs with the use of effective microorganisms

Sewage sludge was taken from a dairy WWTP belonging to Mlekovita Cooperative in Wysokie Mazowieckie. There were excess sludge, flotation sludge and a mixture of excess and flotation sludge from pre-treatment of dairy sewage. The initial content of 16 PAHs in excess sludge before fermentation was approximately 689 µg·kg{sup −1} in dry mass, whereas in post-flotation sludge (which constituted around 30% of raw sludge) it was approximately 95 µg·kg{sup −1} in dry mass. A mixture of excess and flotation sludge had the content of 497,7 µg·kg{sup −1} in dry mass. Through comparison of particular hydrocarbons content in raw sewage sludge to the total PAHs content, it was shown that tricyclic compounds, which constituted 46,3% of the PAHs sum (excess sludge), and tetracyclic compounds, which constituted 60,0% of the PAHs sum (flotation sludge), were the dominating fractions. In the sludge subjected to fermentation in reactors with mixed sludge and surplus activated sludge, the general trend of the course of changes in concentrations of PAHs was similar. Both in the sludge inoculated with EM and in that not inoculated with EM, a significant increase in the total PAHs contents was observed in the first fermentation phase (acidic fermentation) after 7 days of the process. Addition of EM into the sludge did not prevent the PAHs release, and therefore higher concentrations of PAHs sum were recorded during the hydrolysis stage than in sludge before fermentation. A decrease in the sum of PAHs was observed after 2 weeks of fermentation in relation to the quantity observed after 1 week of fermentation (except from post-flotation sludge). In the following weeks, there was further decrease in the concentration of the 16 PAHs sum in all sludge types. However, in sludge without EM inoculation, it was lower than in sludge with EM inoculation. The loss of the majority of tested hydrocarbons was reported in the final phase of fermentation. - Highlights: • The influence of applying Effective Microorganisms on PAHs degradation in dairy sewage sludge during fermentation has been examined. • To study the relationship between quantitative parameters and to describe the correlation strength, Spearman's rank correlation coefficient was used. • In order to verify whether there was a statistically significant change, the Wilcoxon test was applied for individual observation pairs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Fuel property evaluation of unique fatty acid methyl esters containing β-hydroxy esters from engineered microorganisms

Unique fatty acid methyl esters (FAME) containing ..beta..-hydroxy esters were produced using an engineered microorganism by glucose fermentation. This study investigated the properties of the unique FAME mixture both neat and in blends with conventional diesel, as well as properties of ..beta..-hydroxy esters. The unique FAME blend contained relatively shorter-chain FAME (average fatty acid chain carbon number 14.6) with 58 % monounsaturated fatty acids and 9 % saturated and monounsaturated ..beta..-hydroxy acid chains. The unique FAME had significantly lower distillation T90 (321 °C versus 352 °C) and higher cetane number (56.7 versus 52) compared to soy biodiesel. Cloud points were within method repeatability. Unexpectedly (because of the lack of methylene-interrupted double bonds), the unique FAME had low oxidation stability (1.5 h) as determined by Rancimat induction period. Stability could be improved through addition of commonly used antioxidants. We speculate that monounsaturated ..beta..-hydroxy FAME may be the source of this instability. Blends with conventional diesel up to 50 vol% showed similar kinematic viscosity (within method repeatability) as blends of conventional FAME. The unique FAME had no effect on distillation T90 even at the 80% blend level. A 30 vol% blend into conventional diesel had a Rancimat induction period of only 2 h, very nearly the same as the neat unique FAME sample. The addition of antioxidants produced blends of acceptable stability. Based on an assessment of the properties of individual ..beta..-hydroxy FAME molecules, they have higher boiling point, higher cloud point, lower cetane number, and potentially lower storage stability than analogous FAME not having the ..beta..-hydroxy group. Removing them from the fuel product in the production process may result in a biodiesel product with superior properties to what is on the market today.

09 BIOMASS FUELS↗
DOE OSTI2021

Distribution and speciation of Sb and toxic metal(loid)s near an antimony refinery and their effects on indigenous microorganisms

Although several studies have investigated the effects of Sb contamination on surrounding environments and indigenous microorganisms, little is known about the effect of co-contamination of Sb and toxic metal(loid)s. In this study, the occurrence of Sb and other toxic metal(loid)s near an operating Sb refinery and near-field landfill site were investigated. Topsoil samples near the refinery had high Sb levels (~3250 mg kg -1 ) but relatively low concentrations of other toxic metal(loid)s. However, several soil samples taken at greater depth from the near-field landfill site contained high concentrations of As and Pb, as well as extremely high Sb contents (~21,400 mg kg -1 ). X-ray absorption fine structure analysis showed that Sb in the soils from both sites was present as Sb(V) in the form of tripuhyite (FeSbO 4 ), a stable mineral. Three-dimensional principal coordinate analysis showed that microbial community compositions in samples with high toxic metal(loid)s concentrations were significantly different from other samples and had lower microbial populations (~10 4 MPN g -1 ). Sequential extraction results revealed that Sb is present primarily in the stable residual fraction (~99 %), suggesting low Sb bioavailability. Finally, however, microbial redundancy analysis suggested that the more easily extractable Pb might be the major factor controlling microbial community compositions at the site.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2025

Red-Light-Driven Biophotochemical Diode Based on a Microorganism–Silicon Nanowire Interface for Stable and Efficient Bias-Free CO 2 Reduction

Artificial photosynthesis offers a promising route for sustainable liquid fuel and feedstock production, yet integrating efficient CO 2 reduction catalysts with light-harvesting systems remains challenging. Here, in this study, we present a biophotochemical diode that couples microorganism-driven CO 2 reduction with glycerol oxidation, enabled by silicon nanowire photoelectrodes under varying red-light intensities. Tuning the biotic-abiotic interface─by increasing biocatalyst loading and adjusting the catholyte pH to mitigate local alkalization─significantly improves performance and stability. The enhanced-loading biocathode maintains a high faradaic efficiency across a wide potential range, even under elevated light intensities. At 60 mW/cm 2 , the system achieves a bias-free current density of 3.5 mA/cm 2 . Long-term stability testing at 40 mW/cm 2 demonstrates stable operation for over 100 h. The photoanode generates valuable C 3 products, primarily glycerate and lactate, enhancing the economic viability. This work showcases the importance of microenvironmental control at the biotic-abiotic interface and establishes a scalable platform for light-driven CO 2 reduction using earth-abundant silicon.

Artificial Photosynthesis↗
DOE OSTI2013

Mercury methylation by novel microorganisms from new environments

Microbial mercury (Hg) methylation transforms a toxic trace metal into the highly bioaccumulated neurotoxin methylmercury (MeHg). The lack of a genetic marker for microbial MeHg production has prevented a clear understanding of Hg-methylating organism distribution in nature. Recently, a specific gene cluster (hgcAB) was linked to Hg methylation in two bacteria.1 Here we test if the presence of hgcAB orthologues is a reliable predictor of Hg methylation capability in microorganisms, a necessary confirmation for the development of molecular probes for Hg-methylation in nature. Although hgcAB orthologues are rare among all available microbial genomes, organisms are much more phylogenetically and environmentally diverse than previously thought. By directly measuring MeHg production in several bacterial and archaeal strains encoding hgcAB, we confirmed that possessing hgcAB predicts Hg methylation capability. For the first time, we demonstrated Hg methylation in a number of species other than sulfate- (SRB) and iron- (FeRB) reducing bacteria, including methanogens, and syntrophic, acetogenic, and fermentative Firmicutes. Several of these species occupy novel environmental niches for Hg methylation, including methanogenic habitats such as rice paddies, the animal gut, and extremes of pH and salinity. Identification of these organisms as Hg methylators now links methylation to discrete gene markers in microbial communities.

Hg↗