Engineering topics

Isern, Nancy G.

Publications and source records attributed to Isern, Nancy G..

17 records

DOE OSTI2021

MetFish: a Metabolomics Pipeline for Studying Microbial Communities in Chemically Extreme Environments

Metabolites have essential roles in microbial communities, including as mediators of nutrient and energy exchange, cell-to-cell communication, and antibiosis. However, detecting and quantifying metabolites and other chemicals in samples having extremes in salt or mineral content using liquid chromatography-mass spectrometry (LC-MS)-based methods remains a significant challenge. Here, we report a facile method based on in situ chemical derivatization followed by extraction for analysis of metabolites and other chemicals in hypersaline samples, enabling for the first time direct LC-MS-based exometabolomics analysis in sample matrices containing up to 2 M total dissolved salts. The method, MetFish, is applicable to molecules containing amine, carboxylic acid, carbonyl, or hydroxyl functional groups, and it can be integrated into either targeted or untargeted analysis pipelines. In targeted analyses, MetFish provided limits of quantification as low as 1 nM, broad linear dynamic ranges (up to 5 to 6 orders of magnitude) with excellent linearity, and low median interday reproducibility (e.g., 2.6%). MetFish was successfully applied in targeted and untargeted exometabolomics analyses of microbial consortia, quantifying amino acid dynamics in the exometabolome during community succession; in situ in a native prairie soil, whose exometabolome was isolated using a hypersaline extraction; and in input and produced fluids from a hydraulically fractured well, identifying dramatic changes in the exometabolome over time in the well.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2021

Proteome specialization of anaerobic fungi during ruminal degradation of recalcitrant plant fiber

The rumen harbors a complex microbial mixture of archaea, bacteria, protozoa, and fungi that efficiently breakdown plant biomass and its complex dietary carbohydrates into soluble sugars that can be fermented and subsequently converted into metabolites and nutrients utilized by the host animal. While rumen bacterial populations have been well documented, only a fraction of the rumen eukarya are taxonomically and functionally characterized, despite the recognition that they contribute to the cellulolytic phenotype of the rumen microbiota. To investigate how anaerobic fungi actively engage in digestion of recalcitrant fiber that is resistant to degradation, we resolved genome-centric metaproteome and metatranscriptome datasets generated from switchgrass samples incubated for 48 h in nylon bags within the rumen of cannulated dairy cows. Across a gene catalog covering anaerobic rumen bacteria, fungi and viruses, a significant portion of the detected proteins originated from fungal populations. Intriguingly, the carbohydrate-active enzyme (CAZyme) profile suggested a domain-specific functional specialization, with bacterial populations primarily engaged in the degradation of hemicelluloses, whereas fungi were inferred to target recalcitrant cellulose structures via the detection of a number of endo- and exo-acting enzymes belonging to the glycoside hydrolase (GH) family 5, 6, 8, and 48. Notably, members of the GH48 family were amongst the highest abundant CAZymes and detected representatives from this family also included dockerin domains that are associated with fungal cellulosomes. A eukaryote-selected metatranscriptome further reinforced the contribution of uncultured fungi in the ruminal degradation of recalcitrant fibers. These findings elucidate the intricate networks of in situ recalcitrant fiber deconstruction, and importantly, suggest that the anaerobic rumen fungi contribute a specific set of CAZymes that complement the enzyme repertoire provided by the specialized plant cell wall degrading rumen bacteria.

Hagen, Live↗

DOE OSTI2020

Temporospatial shifts in the human gut microbiome and metabolome after gastric bypass surgery

Although the etiology of obesity is not well-understood, genetic, environmental, and microbiome elements are recognized as contributors to this rising pandemic. For morbid obesity, Roux-en-Y gastric bypass (RYGB) surgery alters the fecal microbiome, but data are sparse on temporal and spatial changes in the microbiome and metabolome. We characterized the structure and metabolism of the microbial communities in the gut lumen and on mucosal surfaces in morbidly obese individuals before and after RYGB surgery, and we compared our longitudinal cohort to a previously studied cross-sectional one. RYGB concurrently changed the gut microbiome and led to improvements of obesity comorbidities. Changes in the gut microbiome were reflected in the metabolome, including fermentation products and bile acids. The effects persisted 12 months post-surgery, and the microbiomes and metabolomes were similar to those found for the cross-sectional RYGB cohort. Thus, RYGB surgery had profound and persistent impacts on the intestinal microbiome and metabolome.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2019

Metabolic Response to Stress by the Immature Right Ventricle Exposed to Chronic Pressure Overload

Background: The right ventricle (RV) exposed to chronic pressure overload exhibits hypertrophy and decompensates when exposed to stress. We hypothesize that impaired ability to increase myocardial oxidative flux through pyruvate dehydrogenase (PDH) leads to hypertrophied RV dysfunction when exposed to hemodynamic stress, and PDH stimulation can improve RV function. Methods and Results: Infant male Yorkshire piglets (13.5 ± 0.6 kg weight, n = 19) were used to assess substrate fractional contribution to the citric acid cycle after sustained pulmonary artery banding (PAB). Carbon 13-labeled glucose, lactate, and leucine, oxidative substrate tracers for the citric acid cycle, were infused into right coronary artery on 7-10 days after PAB. RV systolic pressure, RV free wall thickness and individual cardiomyocyte cell size after PAB were significantly elevated compared to Sham. Both fractional glucose and lactate oxidations in PAB group were > 2-fold higher than in Sham. Pigs with overdrive atrial pacing (~80% increase in heart rate) stress after PAB showed only 22% increase in rate-pressure product (RPP) from the baseline before atrial pacing and the limited carbohydrate oxidation rate in RV. Intracoronary infusion of dichloroacetate, a PDH agonist produced higher RPP (59% increase) in response to increased work-load by atrial pacing in association with a marked increase in lactate oxidation. Conclusions: The immature hypertrophied RV shows limited ability to increase carbohydrate oxidation in response to tachycardic stress leading to energy supply/utilization imbalance and decreased systolic function. Enhanced PDH activation by dichloroacetate increases energy supply and preserves hypertrophied RV contractile function during hemodynamic stress.

myocardial metabolism, congenital heart disease, r↗

DOE OSTI2019

Human Gut Microbiota from Autism Spectrum Disorder Promote Behavioral Symptoms in Mice

Large-scale phosphoproteomics with coverage of over 10,000 sites of phosphorylation have now been routinely achieved with advanced mass spectrometry (MS)-based workflows. However, accurate targeted MS-based quantification of phosphorylation dynamics, an important direction for gaining quantitative understanding of signaling pathways or networks, has been much less investigated. Herein, we report an assessment of the targeted workflow in the context of signal transduction pathways, using the epidermal growth factor receptor (EGFR)–mitogen-activated protein kinase (MAPK) pathway as our model. 43 phosphopeptides from the EGFR–MAPK pathway were selected for the study. The recovery and sensitivity of a workflow consisted of two commonly used enrichment methods, immobilized metal affinity chromatography (IMAC) and titanium oxide (TiO2), combined with selected reaction monitoring (SRM)-MS, were evaluated. The recovery of phosphopeptides by IMAC and TiO2 enrichment was quantified to be 38 ± 5% and 58 ± 20%, respectively, based on internal standards. Moreover, both enrichment methods provided comparable sensitivity from 1-100 g starting peptides. Robust quantification was consistently achieved for most targeted phosphopeptides when starting with 25-100 g peptides. However, the numbers of quantified targets significantly dropped when peptide samples were in the 1-25g range. Finally, IMAC-SRM was applied to quantify signaling dynamics of EGFR-MAPK pathway in Hs578T cells following 3 ng/mL EGF treatment. The kinetics of phosphorylation clearly revealed early and late phases of phosphorylation, even for very low abundance proteins. These results demonstrate the feasibility of robust targeted quantification of phosphorylation dynamics for specific pathways, even starting with relatively small amounts of protein.

Sharon, Gil↗

DOE OSTI2018

Characterization of coffee (Coffea arabica) husk lignin and degradation products obtained after oxygen and alkali addition

The full use of biomass in future biorefineries has stimulated studies on utilization of lignin from agricultural crops, such as coffee husk, a major residue from coffee processing. This study focuses on characterizing the lignin obtained from coffee husk and its further wet oxidation products as a function of alkali loading, temperature and residence time. The lignin fraction after diluted acid and alkali pretreatments is composed primarily of p-hydroxylphenyl units (≥ 49%), with fewer guaiacyl and syringyl units. Linkages appear to be mainly β-O-4 ether linkages. Thermal degradation of pretreated lignin occurred in two stages. Carboxylic acids were the main degradation product. Due to the condensed structure of this lignin, relatively low yields of aromatic aldehydes were achieved, except from conditions with temperatures over 210 °C, 5 min residence time and 11.7wt% NaOH. Optimization of the pretreatment and oxidation parameters are important to maximizing yield of higher-value bioproducts from lignin.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2018

Metabolic Response of the Immature Right Ventricle to Acute Pressure Overloading

Background Surgical palliation or repair of complex congenital heart disease in early infancy can produce right ventricular (RV) pressure overload, often leading to acute hemodynamic decompensation. The mechanisms causing this acute RV dysfunction remain unclear. We tested the hypothesis that the immature right ventricle lacks the ability to modify substrate metabolism in order to meet increased energy demands induced by acute pressure overloading. Methods and Results Twenty-two infant male mixed breed Yorkshire piglets were randomized to a sham operation (Control) or pulmonary artery banding yielding >2-fold elevation over baseline RV systolic pressure. We used carbon 13 ( 13 C)-labeled substrates and proton nuclear magnetic resonance to assess RV energy metabolism. [Phosphocreatine]/[ATP] was significantly lower after pulmonary artery banding. [Phosphocreatine]/[ATP] inversely correlated with energy demand indexed by maximal sustained RV systolic pressure/left ventricular systolic pressure. Fractional contributions of fatty acids to citric acid cycle were significantly lower in the pulmonary artery banding group than in the Control group (medium-chain fatty acids; 14.5±1.6 versus 8.2±1.0%, long-chain fatty acids; 9.3±1.5 versus 5.1±1.1%). 13 C-flux analysis showed that flux via pyruvate decarboxylation did not increase during RV pressure overloading. Conclusions Acute RV pressure overload yielded a decrease in [phosphocreatine]/[ATP] ratio, implying that ATP production did not balance the increasing ATP requirement. Relative fatty acids oxidation decreased without a reciprocal increase in pyruvate decarboxylation. The data imply that RV inability to adjust substrate oxidation contributes to energy imbalance, and potentially to contractile failure. The data suggest that interventions directed at increasing RV pyruvate decarboxylation flux could ameliorate contractile dysfunction associated with acute pressure overloading.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Differences in fecal microbial metabolites and microbiota of children with autism spectrum disorders

Evidence supporting that gut problems are linked to ASD symptoms has been accumulating both in humans and animal models of ASD. Gut microbes and their metabolites may be linked not only to GI problems but also to ASD behavior symptoms. Despite this high interest, most previous studies have looked mainly at microbial structure, and studies on fecal metabolites are rare in the context of ASD. Thus, we aimed to detect fecal metabolites that may be present at significantly different concentrations between 21 children with ASD and 23 neurotypical children and to investigate its possible link to human gut microbiome. Using NMR spectroscopy and 16S rRNA gene amplicon sequencing, we examined metabolite profiles and microbial compositions in fecal samples, respectively. Of the 59 metabolites detected, isopropanol concentrations were significantly higher in feces of children with ASD after multiple testing corrections. We also observed similar trends of fecal metabolites to previous studies; children with ASD have higher fecal p-cresol and possibly lower GABA concentrations. In addition, Fisher Discriminant Analysis (FDA) with leave-out-validation suggested that a group of metabolites- caprate, nicotinate, glutamine, thymine, and aspartate- may potentially function as a biomarker to separate ASD participants from the neurotypical group (78% sensitivity and 81% specificity). Consistent with our previous Arizona cohort study, we also confirmed lower gut microbial diversity and reduced relative abundances of Prevotella copri in children with ASD. After multiple testing corrections, we also learned that relative abundances of Feacalibacterium prausnitzii and Haemophilus parainfluenzae were lower in feces of children with ASD. Despite a relatively short list of fecal metabolites, the data in this study support that children with ASD have altered metabolite profiles in feces when compared with neurotypical children and warrant further investigation of metabolites in larger cohorts.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2018

Solubilization and Upgrading of High Polyethylene Terephthalate Loadings in a Low-Costing Bifunctional Ionic Liquid

Polyethylene terephthalate (PET) is of significant commercial importance, but is difficult to recycle. Chemical inertness and resistance to biodegradation make the recycling of PET challenging and most solvents for PET are highly toxic. In this work, we demonstrate for the first time that a low cost (~$1.2/kg) and biocompatible ionic liquid (IL), cholinium phosphate ([Ch]3[PO4]) can play bifunctional roles in PET solubilization and glycolytic degradation. High loading of PET (10 wt%) is readily dissolved in [Ch]3[PO4] at relatively low temperatures (120 °C, 1h) and even in water-rich conditions. Tandem in situ confocal microscopy and Fourier Transform Infrared (FTIR) spectroscopy studies give detailed information on the solubilization mechanism in terms of morphological and chemical changes that occur. In depth analysis of PET-IL solution reveals that the high PET solubilization in [Ch]3[PO4] can be ascribed to significant PET depolymerization. Acid precipitation yields terephthalic acid as the dominant depolymerized monomer with a theoretical yield of ~95%. Further exploration shows that in the presence of ethylene glycol, [Ch]3[PO4] catalyzed glycolysis of PET can efficiently occur with ~100% PET conversion and ~60.6% bis(2-hydroxyethyl)terephthalate (BHET) yield under metal free conditions. The IL can be reused at least three times without an apparent decrease in activity. NMR analysis reveals that strong hydrogen bond interactions between EG and the IL play an important role for EG activation and promotion of the glycolysis reaction. This study opens up avenues for exploring environmentally benign and efficient technology of ILs for solubilizing and recycling postconsumer polyester plastics.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2018

Characterization of Lignin Streams during Bionic Liquid-Based Pretreatment from Grass, Hardwood, and Softwood

Delignification as a function of ionic liquid (IL) pretreatment has potential in terms of recovering and converting the fractionated lignin streams to renewable products. Renewable biogenic ionic liquids, or bionic liquids (eg. cholinium lysinate, ([Ch][Lys])), provide opportunities in terms of effective, economic and sustainable lignocellulosic biomass pretreatment. We have evaluated [Ch][Lys] pretreatment in terms of sugar and lignin yields for three different feedstocks: switchgrass, eucalyptus, and pine. Four lignin streams isolated during [Ch][Lys] pretreatment and enzymatic hydrolysis were comprehensively analyzed, tracking their changes in physical-chemical structures. We observed changes in major lignin linkages and lignin aromatics units (p-hydroxyphenyl (H), guaiacyl (G), and syringil (S)) that occurred during pretreatment. A compositional analysis of the different process streams and a comprehensive mass balance in conjunction with multiple analytical techniques (Nuclear Magnetic Resonance (NMR), Mass Spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC)) is presented. Qualitative and quantitative analyses indicates that there are significantly more lignin-carbohydrate interactions for G-rich lignin in pine. The lignin removal and extent of lignin depolymerization for switchgrass and eucalyptus were higher than pine, and follows the order of switchgrass > eucalyptus > pine. The recovered lignin from pretreated liquid contained a lower relative amount of carbohydrate signals than raw biomass, indicating a high degree of dissociation of lignin carbohydrate complex (LCC) linkages for all samples analyzed. The insights gained from this work contribute to better understanding of physiochemical properties of lignin streams generated during [Ch][Lys] pretreatment, offering a starting point for lignin valorization strategies.

lignin, ionic liquids, NMR↗

DOE OSTI2017

Survey of Lignin-Structure Changes and Depolymerization during Ionic Liquid Pretreatment

A detailed study of chemical changes in lignin structure during the ionic liquid (IL) pretreatment process is not only pivotal for understanding and overcoming biomass recalcitrance during IL pretreatment, but also is necessary for designing new routes for lignin valorization. Chemical changes in lignin were systematically studied as a function of pretreatment temperature, time and type of IL used. Kraft lignin was used as the lignin source and common pretreatment conditions were employed using three different ILs of varying chemical structure in terms of acidic or basic character. The chemical changes in the lignin structure due to IL pretreatment processes were monitored using 1H-13C HSQC NMR, 31P NMR, elemental analysis, GPC, FT-IR, and the depolymerized products were analyzed using GC-MS. Although pretreatment in acidic IL, triethylammonium hydrogensulfate ([TEA][HSO4]) results in maximum decrease in β-aryl ether bond, maximum dehydration and recondensation pathways were also evident, with the net process showing a minimum decrease in the molecular weight of regenerated lignin. However, 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) pretreatment yields a smaller decrease in the β-aryl ether content along with minimum evidence of recondensation, resulting in the maximum decrease in the molecular weight. Cholinium lysinate ([Ch][Lys]) pretreatment shows an intermediate result, with moderate depolymerization, dehydration and recondensation observed. The depolymerization products after IL pretreatment are found to be a function of the pretreatment temperature and the specific chemical nature of the IL used. At higher pretreatment temperature, [Ch][Lys] pretreatment yields guaiacol, [TEA][HSO4] yields guaiacylacetone, and [C2C1Im][OAc] yields both guaiacol and guaiacylacetone as major products. These results clearly indicate that the changes in lignin structure as well as the depolymerized product profile depend on the pretreatment conditions and the nature of the ILs. The insight gained on lignin structure changes and possible depolymerized products during IL pretreatment process would help future lignin valorization efforts in a potential IL-based lignocellulosic biorefinery.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

Distinctive microbiomes and metabolites linked with weight loss after gastric bypass, but not gastric banding

Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB) are anatomically different bariatric operations. RYGB achieves greater weight loss compared with LAGB. Changes in the gut microbiome have been documented after RYGB, but not LAGB, and the microbial contribution to sustainable surgical weight loss warrants further evaluation. We hypothesized that RYGB imposes greater changes on the microbiota and its metabolism than LAGB, and that the altered microbiota may contribute to greater weight loss. Using multi-omic approaches, we analyzed fecal microbial community structure and metabolites of pre-bariatric surgery morbidly obese (PreB-Ob), normal weight (NW), post-RYGB, and post-LAGB participants. RYGB microbiomes were significantly different from those from NW, LAGB and PreB-Ob. Microbiome differences between RYGB and PreB- Ob populations were mirrored in their metabolomes. Diversity was higher in RYGB compared with LAGB, possibly because of an increase in the abundance of facultative anaerobic, bile-tolerant and acid-sensible microorganisms in the former. Possibly because of lower gastric acid exposure, phylotypes from the oral cavity, such as Escherichia, Veillonella and Streptococcus, were in greater abundance in the RYGB group, and their abundances positively correlated with percent excess weight loss. Many of these post-RYGB microorganisms are capable of amino-acid fermentation. Amino-acid and carbohydrate fermentation products—isovalerate, isobutyrate, butyrate and propionate—were prevalent in RYGB participants, but not in LAGB participants. RYGB resulted in greater alteration of the gut microbiome and metabolome than LAGB, and RYGB group exhibited unique microbiome composed of many amino-acid fermenters, compared with nonsurgical controls.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2017

Chemoselective Methylation of Phenolic Hydroxyl Group Prevents Quinone Methide Formation and Repolymerization During Lignin Depolymerization

Chemoselective blocking of the phenolic hydroxyl (Ar-OH) group by methylation was found to suppress secondary repolymerization and charring during lignin depolymerization. Methylation of Ar-OH prevents formation of reactive quinone methide intermediates, which are partly responsible for undesirable secondary repolymerization reactions. Instead, this structurally modified lignin produces more relatively low molecular weight products from lignin depolymerization compared to unmodified lignin. This result demonstrates that structural modification of lignin is desirable for production of low molecular weight phenolic products. This approach could be directed toward alteration of natural lignification processes to produce biomass more amenable to chemical depolymerization.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2017

Modeling framework for isotopic labeling of heteronuclear moieties

Background: Isotopic labeling is an analytic technique that is used to track the movement of isotopes through reaction networks. In general, the applicability of isotopic labeling techniques is limited to the investigation of reaction networks that consider homonuclear moieties, whose atoms are of one tracer element with two isotopes, distinguished by the presence of one additional neutron. Results: This article presents a reformulation of the modeling framework for isotopic labeling, generalized to arbitrarily large, heteronuclear moieties, arbitrary numbers of isotopic tracer elements, and arbitrary numbers of isotopes per element, distinguished by arbitrary numbers of additional neutrons. Conclusions: With this work, it is now possible to simulate the isotopic labeling states of metabolites in completely arbitrary biochemical reaction networks.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Selective cerebral perfusion prevents abnormalities in glutamate cycling and neuronal apoptosis in a model of infant deep hypothermic circulatory arrest and reperfusion

Rationale: Deep hypothermic circulatory arrest (DHCA) is often required for the repair of complex congenital cardiac defects in infants. However, DHCA induces neuroapoptosis associated with later development of neurocognitive abnormalities. Selective cerebral perfusion (SCP) theoretically provides superior neural protection possibly through modifications in cerebral substrate oxidation and closely integrated glutamate cycling. Objectives: We tested the hypothesis that SCP modulates glucose entry into the citric acid cycle, and ameliorates abnormalities in glutamate flux which occur in association neuroapoptosis during DHCA. Methods and Results: Eighteen male Yorkshire piglets (age 34-44 days) were assigned randomly to 2 groups of 7 (DHCA or DHCA with SCP for 60 minutes at 18 °C) and 4 control pigs without cardiopulmonary bypass support. After the completion of rewarming from DHCA, 13-Carbon-labeled (13C) glucose as a metabolic tracer was infused. We used gas chromatography-mass spectrometry (GCMS) and nuclear magnetic resonance for metabolic analysis in the frontal cortex. Following 2.5 hours of cerebral reperfusion, we observed similar cerebral ATP levels, absolute levels of lactate and citric acid cycle intermediates, and 13C-enrichment. However, DHCA induced significant abnormalities in glutamate cycling resulting in reduced glutamate/glutamine and elevated γ-aminobutyric acid (GABA)/glutamate along with neuroapoptosis (TUNEL), which were all prevented by SCP. Conclusions: DHCA alone induces abnormalities in cycling of the major neurotransmitters in association with neuroapoptosis, but does not alter cerebral glucose utilization during reperfusion. The data suggest that SCP prevents these modifications in glutamate/glutamine/GABA cycling and protects the cerebral cortex from neuroapoptosis.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2016

Formaldehyde as a carbon and electron shuttle between autotroph and heterotroph populations in acidic hydrothermal vents of Norris Geyser Basin, Yellowstone National Park

The Norris Geyser Basin in Yellowstone National Park contains a large number of hydrothermal systems, which host microbial populations supported by primary productivity associated with a suite of chemolithotrophic metabolisms. We demonstrate that Metallosphaera yellowstonesis MK1, a facultative autotrophic archaeon isolated from a hyperthermal acidic hydrous ferric oxide (HFO) spring in Norris Geyser Basin, excretes formaldehyde during autotrophic growth. To determine the fate of formaldehyde in this low organic carbon environment, we incubated native microbial mat (containing M. yellowstonensis) from a HFO spring with 13C-formaldehyde. Isotopic analysis of incubation-derived CO2 and biomass showed that formaldehyde was both oxidized and assimilated by members of the community. Autotrophy, formaldehyde oxidation, and formaldehyde assimilation displayed different sensitivities to chemical inhibitors, suggesting that distinct sub-populations in the mat selectively perform these functions. Our results demonstrate that electrons originally resulting from iron oxidation can energetically fuel autotrophic carbon fixation and associated formaldehyde excretion, and that formaldehyde is both oxidized and assimilated by different organisms within the native microbial community. Thus, formaldehyde can effectively act as a carbon and electron shuttle connecting the autotrophic, iron oxidizing members with associated heterotrophic members in the HFO community.

acidophilic↗

DOE OSTI2016

Rapid room temperature solubilization and depolymerization of polymeric lignin at high loadings

The relatively poor solubility of lignin in most pretreatment solvents remains one of the biggest challegnes in lignin valorization to improve overall biorefinery economics. In this work, rapid room temperature solubilization of lignin at high solid loadings (>30 wt%) can be easily achieved in a single step using ethylene glycol (EG). The solubilized lignin can be rapidly and quantitively recovered with the addtion of ethanol. The computational and nuclear magnetic resonance (NMR) spectroscopic studies confirm that strong hydrogen bond interactions between EG and the free hydroxyl groups present in lignin contribute to the lignin dissolution. In addition, hydrogen peroxide mediated depolymerization of dissolved lignin at low temperature (80 oC) was tested and the effect of EG molecules on depolymerization of ligin was also theoritically studied. The findings of this work provide mechanistic insights of hydrogen bond interactions in high lignin solubilization and valorization.

Environmental Molecular Sciences Laboratory↗