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At least 883 records · Page 49

All sources NASA NTRS DOE OSTI

NASA NTRS1999

Characterization of Human Bone Alkaline Phosphatase in Pichia Pastoris

A soluble form of human bone alkaline phosphatase has been expressed in a recombinant strain of the methylotrophic yeast Pichia pastoris. We constructed a plasmid containing cDNA encoding for human bone alkaline phosphatase, with the hydrophobic carboxyl terminal portion deleted. Alkaline phosphatase was secreted into the medium to a level of 32mg/L when cultured in shake flasks, and enzyme activity was 12U/mg, as measured by a spectrophotometric assay. By conversion to a fermentation system, a yield of 880mg/L has been achieved with an enzyme activity of 968U/mg. By gel electrophoresis analysis, it appears that greater than 50% of the total protein in the fermentation media is alkaline phosphatase. Although purification procedures are not yet completely optimized, they are expected to include filtration, ion exchange and affinity chromatography. Our presentation will focus on the purification and crystallization results up to the time of the conference. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

Malone, Christine C.↗

NASA NTRS1996

Redox Disproportionation of Glucose as a Major Biosynthetic Energy Source

Previous studies have concluded that very little if any energy is required for the microbial biosynthesis of amino acids and lipids from glucose -- processes that yield almost as much ATP (adenosine triphosphate) as they consume. However, these studies did not establish the strength nor the nature of the energy source driving these biological transformations. To identify and estimate the strength of the energy source behind these processes, we calculated the free energy change due to the redox disproportionation of substrate carbon of (a) 26 redox-balanced fermentation reactions, and (b) the biosynthesis of amino acids, lipids, and nucleotides of E. coli from glucose. A plot of the negative free energy of these reactions per mmole of carbon as a function of the number of disproportionative electron transfers per mmol of carbon showed that the energy yields of these fermentations and biosyntheses were directly proportional to the degree of redox disproportionation of carbon. Since this linear relationship showed that redox disproportionation was the dominant energy source of these reactions, we were able to establish that amino acid and lipid biosynthesis obtained most of their energy from redox disproportionation (greater than 94%). In contrast nucleotide biosynthesis was not driven by redox disproportionation of carbon, and consequently depended completely on ATP for energy. This crucial and previously unrecognized role of sugars as an energy source of biosynthesis suggests that sugars were involved at the earliest stage in the origin of anabolic metabolism.

Weber, Arthur L.↗

NASA NTRS2001

Development of a Supported Emulsion Liquid Membrane System for Propionic Acid Separation in a Microgravity Environment

Perstractive fermentation is a good way to increase the productivity of bioreactors. Using Propionibacteria as the model system, the feasibility of using supported emulsion liquid membrane (SELM) for perstractive fermentation is assessed in this study. Five industrial solvents were considered as the solvent for preparing the SELM. The more polar a solvent is, the higher the partition coefficient. However, toxicity of a solvent also increases with its polarity. CO-1055 (industrial decanol/octanol blend) has the highest partition coefficient toward propionic acid among the solvents that has no molecular toxicity toward Propionibacteria. A preliminary extraction study was conducted using tetradecane as solvent in a hydrophobic hollow fiber contactor. The result confirmed that SELM eliminates the equilibrium limitation of conventional liquid-liquid extraction, and allows the use of a non-toxic solvent with low partition coefficient.

Li, Jin↗

NASA NTRS2001

Evidence of root zone hypoxia in Brassica rapa L. grown in microgravity

A series of experiments was conducted aboard the U.S. space shuttle and the Mir space station to evaluate microgravity-induced root zone hypoxia in rapid-cycling Brassica (Brassica rapa L.), using both root and foliar indicators of low-oxygen stress to the root zone. Root systems from two groups of plants 15 and 30 d after planting, grown in a phenolic foam nutrient delivery system on the shuttle (STS-87), were harvested and fixed for microscopy or frozen for enzyme assays immediately postflight or following a ground-based control. Activities of fermentative enzymes were measured as indicators of root zone hypoxia and metabolism. Following 16 d of microgravity, ADH (alcohol dehydrogenase) activity was increased in the spaceflight roots 47% and 475% in the 15-d-old and 30-d-old plants, respectively, relative to the ground control. Cytochemical localization showed ADH activity in only the root tips of the space-grown plants. Shoots from plants that were grown from seed in flight in a particulate medium on the Mir station were harvested at 13 d after planting and quick-frozen and stored in flight in a gaseous nitrogen freezer or chemically fixed in flight for subsequent microscopy. When compared to material from a high-fidelity ground control, concentrations of shoot sucrose and total soluble carbohydrate were significantly greater in the spaceflight treatment according to enzymatic carbohydrate analysis. Stereological analysis of micrographs of sections from leaf and cotyledon tissue fixed in flight and compared with ground controls indicated no changes in the volume of protoplast, cell wall, and intercellular space in parenchyma cells. Within the protoplasm, the volume occupied by starch was threefold higher in the spaceflight than in the ground control, with a concomitant decrease in vacuolar volume in the spaceflight treatment. Both induction of fermentative enzyme activity in roots and accumulation of carbohydrates in foliage have been repeatedly shown to occur in response to root zone oxygen deprivation. These results indicate that root zone hypoxia is a persistent challenge in spaceflight plant growth experiments and may be caused by microgravity-induced changes in fluid and gas distribution.

long duration↗

NASA NTRS1996

Enzyme conversion of lignocellulosic plant materials for resource recovery in a Controlled Ecological Life Support System

A large amount of inedible plant material composed primarily of the carbohydrate materials cellulose, hemicellulose, and lignin is generated as a result of plant growth in a Controlled Ecological Life-Support System (CELSS). Cellulose is a linear homopolymer of glucose, which when properly processed will yield glucose, a valuable sugar because it can be added directly to human diets. Hemicellulose is a heteropolymer of hexoses and pentoses that can be treated to give a sugar mixture that is potentially a valuable fermentable carbon source. Such fermentations yield desirable supplements to the edible products from hydroponically-grown plants such as rapeseed, soybean, cowpea, or rice. Lignin is a three-dimensionally branched aromatic polymer, composed of phenyl propane units, which is susceptible to bioconversion through the growth of the white rot fungus, Pluerotus ostreatus. Processing conditions, that include both a hot water pretreatment and fungal growth and that lead to the facile conversion of plant polysaccharides to glucose, are presented.

NASA Discipline Number 93-10↗

DOE OSTI2012

Conversion of residual organics in corn stover-derived biorefinery stream to bioenergy via microbial fuel cell

A biorefinery process typically uses about 4-10 times as much water as the amount of biofuel generated. The wastewater produced in a biorefinery process contains residual sugars, 5-furfural, phenolics, and other pretreatment and fermentation byproducts. Treatment of the wastewater can reduce the need for fresh water and potentially add to the environmental benefits of the process. Use of microbial fuel cells (MFCs) for conversion of the various organics present in a post-fermentation biorefinery stream is reported here. The organic loading was varied over a wide range to assess removal efficiency, coulombic efficiency and power production. A coulombic efficiency of 40% was observed for a low loading of 1% (0.66 g/L) and decreased to 1.8% for the undiluted process stream (66.4 g/L organic loading). A maximum power density of 1180 mW/m2 was observed at a loading of 8%. Excessive loading was found to result in poor electrogenic performance. The results indicate that operation of an MFC at an intermediate loading using dilution and recirculation of the process stream can enable effective treatment with bioenergy recovery.

Borole, Abhijeet P↗

DOE OSTI2012

Synergistic Hydrogen Production in a Biorefinery via Bioelectrochemical Systems

Microbial electrolysis cells are devices that use biocatalysis and electrolysis for production of hydrogen from organic matter. Biorefinery process streams contain fermentation by products and inhibitors which accumulate in the process stream if the water is recycled. These molecules also affect biomass to biofuel yields if not removed from the recycle water. The presence of sugar- and lignin- degradation products such as furfural, vanillic acid and 4-hydroxybenzaldehyde has been shown to reduce fermentation yields. In this work, we calculate the potential for hydrogen production using microbial electrolysis cells from these molecules as substrates. Conversion of these substrates to electricity is demonstrated in microbial fuel cells and will also be presented.

08 HYDROGEN↗

DOE OSTI2013

Twenty-Seventh Fungal Genetics Conference, Asilomar, CA, March 12-17, 2013

This meeting brings together ~900 international scientists to discuss the latest research on fungal genetics. Sessions of particular relevance to DOE include lignocellulose degradation, cellulose conversion to fermentable sugars, fermentation of sugars to fuel molecules. Other sessions cover fungal diseases of biomass crops (miscanthus, corn, switchgrass, etc.).

09 BIOMASS FUELS↗

DOE OSTI2014

Recombinant host cells and media for ethanol production

Disclosed are recombinant host cells suitable for degrading an oligosaccharide that have been optimized for growth and production of high yields of ethanol, and methods of making and using these cells. The invention further provides minimal media comprising urea-like compounds for economical production of ethanol by recombinant microorganisms. Recombinant host cells in accordance with the invention are modified by gene mutation to eliminate genes responsible for the production of unwanted products other than ethanol, thereby increasing the yield of ethanol produced from the oligosaccharides, relative to unmutated parent strains. The new and improved strains of recombinant bacteria are capable of superior ethanol productivity and yield when grown under conditions suitable for fermentation in minimal growth media containing inexpensive reagents. Systems optimized for ethanol production combine a selected optimized minimal medium with a recombinant host cell optimized for use in the selected medium. Preferred systems are suitable for efficient ethanol production by simultaneous saccharification and fermentation (SSF) using lignocellulose as an oligosaccharide source. The invention also provides novel isolated polynucleotide sequences, polypeptide sequences, vectors and antibodies.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2014

Overproduction of ligninolytic enzymes

Methods, compositions, and systems for overproducing ligninolytic enzymes from the basidiomycetous fungus are described herein. As described, the method can include incubating a fungal strain of Cerrena unicolor IBB 303 in a fermentation system having growth medium which includes lignocellulosic material and then cultivating the fungal strain in the fermentation system under conditions wherein the fungus expresses the ligninolytic enzymes. In some cases, the lignocellulosic material is mandarin peel, ethanol production residue, walnut pericarp, wheat bran, wheat straw, or banana peel.

09 BIOMASS FUELS↗

DOE OSTI2014

Flow-through biological conversion of lignocellulosic biomass

The present invention is directed to a process for biologically converting carbohydrates from lignocellulosic biomass comprising the steps of: suspending lignocellulosic biomass in a flow-through reactor, passing a reaction solution into the reactor, wherein the solution is absorbed into the biomass substrate and at least a portion of the solution migrates through said biomass substrate to a liquid reservoir, recirculating the reaction solution in the liquid reservoir at least once to be absorbed into and migrate through the biomass substrate again. The biological converting of the may involve hydrolyzing cellulose, hemicellulose, or a combination thereof to form oligosaccharides, monomelic sugars, or a combination thereof; fermenting oligosaccharides, monomelic sugars, or a combination thereof to produce ethanol, or a combination thereof. The process can further comprise removing the reaction solution and processing the solution to separate the ethanol produced from non-fermented solids.

09 BIOMASS FUELS↗

DOE OSTI2014

Flow-through biological conversion of lignocellulosic biomass

09 BIOMASS FUELS↗

DOE OSTI2015

Method and apparatus for treating a cellulosic feedstock

Methods and apparatus for treating, pre-treating, preparing and conveying a cellulosic feedstock, such as for ethanol production, are disclosed. More specifically, the invention relates to methods and apparatus for treating a cellulosic feedstock by mixing and heating the cellulosic feedstock and/or by moistening and heating the cellulosic feedstock. The invention also relates to a holding tank, and a method of utilizing the holding tank whereby bridging may be reduced or eliminated and may result in a product stream from autohydrolysis or hydrolysis having an improved yield. The invention further relates to methods and apparatus for obtaining and conveying a cellulosic feedstock, which may be used for the subsequent production of a fermentable sugar stream from the cellulose and hemicellulose in the cellulosic feedstock wherein the fermentable sugar stream may be used for subsequent ethanol production. The invention also relates to a method and apparatus for withdrawing one or more feedstock stream from a holding tank.

09 BIOMASS FUELS↗

DOE OSTI2015

Development and Optimization of a Flocculation Procedure for Improved Solid-Liquid Separation of Digested Biomass

One viable treatment method for conversion of lignocellulosic biomass to biofuels begins with saccharification (thermochemical pretreatment and enzymatic hydrolysis), followed by fermentation or catalytic upgrading to fuels such as ethanol, butanol, or other hydrocarbons. The post-hydrolysis slurry is typically 4-8 percent insoluble solids, predominantly consisting of lignin. Suspended solids are known to inhibit fermentation as well as poison catalysts and obstruct flow in catalyst beds. Thus a solid-liquid separation following enzymatic hydrolysis would be highly favorable for process economics, however the material is not easily separated by filtration or gravimetric methods. Use of a polyacrylamide flocculant to bind the suspended particles in a corn stover hydrolyzate slurry into larger flocs (1-2mm diameter) has been found to be extremely helpful in improving separation. Recent and ongoing research on novel pretreatment methods yields hydrolyzate material with diverse characteristics. Therefore, we need a thorough understanding of rapid and successful flocculation design in order to quickly achieve process design goals. In this study potential indicators of flocculation performance were investigated in order to develop a rapid analysis method for flocculation procedure in the context of a novel hydrolyzate material. Flocculation conditions were optimized on flocculant type and loading, pH, and mixing time. Filtration flux of the hydrolyzate slurry was improved 170-fold using a cationic polyacrylamide flocculant with a dosing of approximately 22 mg flocculant/g insoluble solids at an approximate pH of 3. With cake washing, sugar recovery exceeded 90 percent with asymptotic yield at 15 L wash water/kg insoluble solids.

09 BIOMASS FUELS↗

DOE OSTI2015

Biocatalysts with enhanced inhibitor tolerance

Disclosed herein are biocatalysts for the production of biofuels, including microorganisms that contain genetic modifications conferring tolerance to growth and fermentation inhibitors found in many cellulosic feedstocks. Methods of converting cellulose-containing materials to fuels and chemicals, as well as methods of fermenting sugars to fuels and chemicals, using these biocatalysts are also disclosed.

09 BIOMASS FUELS↗

DOE OSTI2016

High Titer and Yields Achieved with Novel, Low-Severity Pretreatment Strategy

NREL researchers obtained high concentration sugar syrups in enzymatic hydrolysis that are fermentable to ethanol and other advanced biofuels and intermediate products at high yields. The novel DMR process is simpler and bypasses all severe pretreatment methods, thus reducing the environmental impact. The results are unprecedented. Researchers achieved a high concentration of sugars (230g/L of monomeric sugar and 270 g/L total sugar) and this low toxicity, highly fermentable syrup yielded 86 g/L ethanol (> 90 percent conversion). In addition, the lignin streams from this process can readily be converted to jet or renewable diesel blendstocks through a hydrodeoxygenation step. The NREL-developed, low severity DMR process may potentially replace higher severity chemical pretreatments and associated expensive reactors constructed of exotic alloys with a simpler process, using commercial-scale equipment commonly associated with the pulp and paper industry, to produce high concentration, low toxicity sugar streams and highly reactive lignin streams from non-food renewable biomass for biological and catalytic upgrading to advanced biofuels and chemicals. The simpler DMR process with black liquor recycling could reduce environmental and life-cycle impacts, and repurpose shuttered pulp and paper mills to help revitalize rural economies.

09 BIOMASS FUELS↗

DOE OSTI2016

Life-Cycle Analysis of Energy Use, Greenhouse Gas Emissions, and Water Consumption in the 2016 MYPP Algal Biofuel Scenarios

The Department of Energy (DOE) Bioenergy Technologies Office (BETO) Multi-year Program Plan (MYPP) describes the bioenergy objectives pursued by BETO, the strategies for achieving those objectives, the current state of technology (SOT), and a number of design cases that explore cost and operational performance required to advance the SOT towards middle and long term goals (MYPP, 2016). Two options for converting algae to biofuel intermediates were considered in the MYPP, namely algal biofuel production via lipid extraction and algal biofuel production by thermal processing. The first option, lipid extraction, is represented by the Combined Algae Processing (CAP) pathway in which algae are hydrolyzed in a weak acid pretreatment step. The treated slurry is fermented for ethanol production from sugars. The fermentation stillage contains most of the lipids from the original biomass, which are recovered through wet solvent extraction. The process residuals after lipid extraction, which contain much of the original mass of amino acids and proteins, are directed to anaerobic digestion (AD) for biogas production and recycle of N and P nutrients. The second option, thermal processing, comprises direct hydrothermal liquefaction (HTL) of the wet biomass, separation of aqueous, gas, and oil phases, and treatment of the aqueous phase with catalytic hydrothermal gasification (CHG) to produce biogas and to recover N and P nutrients.

09 BIOMASS FUELS↗

DOE OSTI2017

Expression of enzymes in yeast for lignocellulose derived oligomer CBP

The present invention provides a multi-component enzyme system that hydrolyzes hemicellulose oligomers from hardwood which can be expressed, for example, in yeast such as Saccharomyces cerevisiae. In some embodiments, this invention provides for the engineering of a series of biocatalysts combining the expression and secretion of components of this enzymatic system with robust, rapid xylose utilization, and ethanol fermentation under industrially relevant process conditions for consolidated bioprocessing. In some embodiments, the invention utilizes co-cultures of strains that can achieve significantly improved performance due to the incorporation of additional enzymes in the fermentation system.

09 BIOMASS FUELS↗