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All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Biodiversity and Global Health: Intersection of Health, Security, and the Environment

One of the biggest consequences of large-scale environmental change is the loss of biodiversity. Recent studies predict a loss of 1 million species in the near future. Biodiversity loss and land use change through anthropogenic disturbance are known to affect disease exposure, disease severity, and disease impacts. It is becoming increasingly clear that biodiversity loss will lead to an increase in infectious diseases in certain regions. Changes in biodiversity may contain important signatures for prediction of infectious diseases and outbreaks. Here, we argue that areas of high or rapid biodiversity loss will be critical to monitor under the umbrella of global health security. Global Health Security consists of the actions and activities required to reduce the impact of public health events in populations living in different geographic regions and across international borders. Like infectious diseases, climate change and other causes of environmental changes do not respect international borders and are becoming more widespread in all parts of the world. Here, the relationships among biodiversity, climate and environmental changes, and pathogen prevalence are dynamic, context dependent, and complex. Accounting for this complexity requires the inclusion of the environment sector, presently missing, when evaluating the potential of global health security actions for mitigating disease risks.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Toward a Predictive Understanding of the Response of Belowground Microbial Carbon Turnover to Climate Change Drivers in a Boreal Peatland

Peatlands are wetlands that act as giant "carbon banks", storing approximately one-third of Earth's soil carbon. Peatland carbon banks cover large areas in northern latitudes including the Arctic and evidence from previous work suggests that northern peatlands store a lot of carbon partly because they are cold and microbes don't work very fast to decompose organic matter in the cold. The concern is that with increasing temperatures, microbes will be become more active and release more carbon from the "bank" as greenhouse gases, carbon dioxide and natural gas (methane). However, there are many more factors that could determine why peatlands store so much carbon such as the fact that they are acidic, low in oxygen, or because they contain a peat moss carpet. All of these factors have been shown to slow down the activity of microbes that release greenhouse gases through the decomposition of organic matter. For example, peat mosses naturally produce organic chemical compounds that are thought to poison microbes, thereby limiting their activity. For this reason, peat moss was used in the past as a food preservative. As the amount of carbon dioxide increases in Earth's atmosphere, it also predicted that plants will become more active and produce more usable organic matter for microbes. Therefore, this project addressed the resilience of the peatland carbon bank to warming and the accumulation carbon dioxide in the atmosphere. The project was conducted at the Marcell Experimental Forest (MEF), northern Minnesota, where the Oak Ridge National Lab (ORNL) has established an experimental site known as Spruce and Peatland Response Under Climatic and Environmental Change (SPRUCE). The SPRUCE site simulates environmental change at the ecosystem scale, allowing us to understand how all organisms, from microbes to trees, will respond to higher temperatures and increased carbon dioxide in the atmosphere. From 2014 to 2017, the response of peatlands to environmental change was evaluated through multiple field campaigns each year along with laboratory research. Environmental changes were initiated in stages; soil heating began in 2014, air heating in 2015, and carbon dioxide enrichment in 2016. It was shown that after 1 year, soil heating alone resulted in an exponential increase in methane release to the atmosphere. However, this response was due solely to surface processes and not degradation of deep peat, which represents much older carbon stores. Studies in the laboratory showed that only the top 20–30 cm of peat from experimental plots had higher methane production rates at elevated temperatures. Further investigations using the latest advanced analytical chemistry and microbiology methods confirmed that greenhouse gas production primarily originated from decomposition of organic matter produced recently by plants and not from old peat. No differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities were observed among treatments after 1 year of soil heating alone. The activity and not the abundance of microbial communities responded over this time scale. Subsequent field investigations from 2015 to 2017 supported these initial investigations that changes in chemistry and the release of gases from microbial activity was primarily occurring at the surface of the peatland. Thus, our initial results over the first few years of simulated environmental change indicated that the large store of deep peat carbon will be resistant to anaerobic degradation under future climatic warming. Peatland soils are poor in mineral nutrients, and it was thought previously that the decomposition of plant matter in the soil is controlled by processes leading primarily to methane production (methanogenesis), ultimately producing similar amounts of carbon dioxide and methane during organic matter degradation. However, we observed that much more carbon dioxide is produced than methane from the surface peatland. Using a combination of state of the art molecular techniques, this project showed that novel microbial processes involving the respiration or “breathing” of organic matter itself may be responsible for most of gas release from the peatland as carbon dioxide. This has opened up a whole new area of research in how wetlands respond to environmental change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Surface water areas significantly impacted 2014 dengue outbreaks in Guangzhou, China

Dengue transmission in urban areas is strongly influenced by a range of biological and environmental factors, yet the key drivers still need further exploration. To better understand mechanisms of environment–mosquito–urban dengue transmission, we propose an empirical model parameterized and cross-validated from a unique dataset including viral gene sequences, vector dynamics and human dengue cases in Guangzhou, China, together with a 36-year urban environmental change maps investigated by spatiotemporal satellite image fusion. The dengue epidemics in Guangzhou are highly episodic and were not associated with annual rainfall over time. Our results indicate that urban environmental changes, especially variations in surface area covered by water in urban areas, can substantially alter the virus population and dengue transmission. The recent severe dengue outbreaks in Guangzhou may be due to the surge in an artificial lake construction, which could increase infection force between vector (mainly Aedes albopictus) and host when urban water area significantly increased. Impacts of urban environmental change on dengue dynamics may not have been thoroughly investigated in the past studies and more work needs to be done to better understand the consequences of urbanization processes in our changing world. - Highlights: • Urban dengue outbreak is associated with water area in Guangzhou, 1978–2014. • Surface water area can alter population size of dengue virus in urban area. • Urban dengue outbreak is not associated with annual rainfall in Guangzhou. • Spatiotemporal satellite image fusion can investigate urban environmental change. • Urban environmental change could induce virus, vector, and dengue epidemic change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Aspen Global Change Institute: 25 Years of Interdisciplinary Global Change Science

Global environmental changes such as climate change result from the interaction of human and natural systems. Research to understand these changes and options for addressing them requires the physical, environmental, and social sciences, as well as engineering and other applied fields. In this essay, we describe how the Aspen Global Change Institute (AGCI) has provided leadership in global change science over the past 25 years—in particular how it has contributed to the integration of the natural and social sciences needed to research the drivers of change, Earth system response, natural and human system impacts, and options for risk management. We illustrate the ways the history of AGCI has been intertwined with the evolution of global change science as it has become an increasingly interdisciplinary endeavor.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Iron dissolution from Patagonian dust in the Southern Ocean: under present and future conditions

Although the input of desert dust as a key source of trace metals in the Southern Ocean (SO) has been previously studied, the dissolution process of metals in surface waters, particularly iron (Fe), remain poorly understood. Given the crucial role of Fe in primary production and the biological carbon pump in the SO, we focused on experimental estimations of Fe dissolution from Patagonian dust, the primary natural dust source in the SO. Our study considered both current and projected future conditions, encompassing sea-surface warming, acidification, increased photosynthetically active radiation, and doubled dust inputs. Through controlled laboratory experiments using filtered SO seawater, conducted over 7 days, we assessed changes in particulate Fe (pFe) concentrations, Fe redox speciation (Fe(II)/Fe(III)), and in the mineralogy of Fe-bearing dust in abiotic condition. The predominant minerals in the dust included quartz and aluminosilicates, with silicon (Si), aluminum (Al), and Fe as the major elements. No significant alterations in the mineralogy and the elemental composition of the dust were recorded during the dissolution experiments, neither under present nor under projected future conditions. The particulate Fe(II)/Fe(III) ratio remained consistently at 0.25 during the experiments, unaffected by changed conditions. Consequently, changes in environmental conditions in the SO would therefore not significantly alter the mineralogy and redox speciation of pFe in the Patagonian dust. On the contrary, pFe exhibited a dissolution rate of 3.8% and 1.6% per day under present and future conditions, respectively. The environmental changes anticipated for 2100 in the SO will likely to result in a decrease in the dissolution rate of pFe. Thus, even though a doubling of dust input by 2100 is anticipated, it will unlikely provide significantly more dissolved Fe (dFe) in seawater in the SO. Consequently, the future intensification of Patagonian dust inputs may not alleviate the Fe limitation in the SO.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

When evolution is the solution to pollution: Key principles, and lessons from rapid repeated adaptation of killifish ( Fundulus heteroclitus ) populations

Abstract For most species, evolutionary adaptation is not expected to be sufficiently rapid to buffer the effects of human‐mediated environmental changes, including environmental pollution. Here we review how key features of populations, the characteristics of environmental pollution, and the genetic architecture underlying adaptive traits, may interact to shape the likelihood of evolutionary rescue from pollution. Large populations of Atlantic killifish (Fundulus heteroclitus) persist in some of the most contaminated estuaries of the United States, and killifish studies have provided some of the first insights into the types of genomic changes that enable rapid evolutionary rescue from complexly degraded environments. We describe how selection by industrial pollutants and other stressors has acted on multiple populations of killifish and posit that extreme nucleotide diversity uniquely positions this species for successful evolutionary adaptation. Mechanistic studies have identified some of the genetic underpinnings of adaptation to a well‐studied class of toxic pollutants; however, multiple genetic regions under selection in wild populations seem to reflect more complex responses to diverse native stressors and/or compensatory responses to primary adaptation. The discovery of these pollution‐adapted killifish populations suggests that the evolutionary influence of anthropogenic stressors as selective agents occurs widely. Yet adaptation to chemical pollution in terrestrial and aquatic vertebrate wildlife may rarely be a successful “solution to pollution” because potentially adaptive phenotypes may be complex and incur fitness costs, and therefore be unlikely to evolve quickly enough, especially in species with small population sizes.

Evolutionary Biology↗
DOE OSTI2013

Development of Renewable Biofuels Technology by Transcriptomic Analysis and Metabolic Engineering of Diatoms

There is enormous interest in developing renewable sources of liquid fuels because of depletion of fossil fuel reserves, dependence on foreign sources, and increasing atmospheric CO 2 levels. Algae produce neutral lipids that are readily converted into liquid fuels such as biodiesel or JP-8 equivalent, and are attractive sources because they are far more productive than plants (yielding 10 -100’s of time more lipid per land area), and can be grown on non-cultivatable land with non-potable (brackish or salt) water sources. Unicellular algae known as diatoms were the most thoroughly characterized species in the National Renewable Energy Laboratory’s Aquatic Species Program, whose goal was to develop microalgae as renewable fuel sources. Lipid accumulation in microalgae is generally induced by nutrient limitation, which involves a change in environmental conditions. Intrinsic variability in cellular response to environmental changes prevents a high degree of control over the process. Nutrient limitation also inhibits biomass accumulation; therefore a tradeoff between high biomass and lipid production occurs. The goal of this project was to develop metabolic engineering approaches for diatoms to enable induction of lipid accumulation by controllable manipulation of intracellular processes rather than from external environmental conditions, and to manipulate carbon partitioning within the cell between lipid and carbohydrate synthesis to enable both abundant biomass and lipid accumulation. There were two specific objectives for this project; Objective 1:To perform comparative transcriptomic analysis in T. pseudonana and C. cryptica of lipid accumulation resulting from silicon and nitrogen limitation, to identify common and key regulatory steps involved in controlling lipid accumulation and carbon partitioning; and Objective 2: To metabolically engineer the cell to alter carbon partitioning to either trigger lipid induction without the need for nutrient limitation, or to enable lipid accumulation along with high biomass accumulation.The significance of this project is that it will enable greater control over lipid production in diatoms by manipulable intracellular processes rather than from variable environmental conditions, and it will possibly enable lipid accumulation under normal growth conditions. Current economics dictate the use of open outdoor raceway pond systems for commercial-scale microalgal growth for biofuels production (although advanced design enclosed bioreactors are under consideration, they are currently not cost effective). Outdoor systems are subject to large variability in environmental conditions. In microalgae, lipid accumulation generally occurs under nutrient limiting conditions, which prevents high biomass accumulation. Potentially, one could carefully adjust the level of a particular nutrient so that it would become limiting after sufficient biomass accumulated; however, given the variability inherent in microalgal cellular metabolism under different light, temperature, and nutrient regimes, this will be a relatively uncontrolled and poorly reproducible approach. A better strategy would be to provide ample nutrients, but trigger lipid accumulation “artificially” by manipulating intracellular processes through metabolic engineering. In addition, identifying the key regulatory steps involved in controlling carbon partitioning in the cell coupled with metabolic engineering should enable greater partitioning of carbon into lipids during non-limiting nutrient growth conditions. The approaches outlined in this proposal are aimed at achieving these goals, and are expected to have a substantial impact on the development of renewable biofuels technology. Development of the approaches described in this proposal will provide a rich interdisciplinary educational experience for high school and undergraduate students to foster their development in a scientific career.

09 BIOMASS FUELS↗
DOE OSTI2017

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. Here, we aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix laricina, Rhododendron groenlandicum, and Chamaedaphne calyculata. The fine roots of trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Finally, the dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Leveraging Machine Learning and Geo-Tagged Citizen Science Data to Disentangle the Factors of Avian Mortality Events at the Species Level

Abrupt environmental changes can affect the population structures of living species and cause habitat loss and fragmentations in the ecosystem. During August–October 2020, remarkably high mortality events of avian species were reported across the western and central United States, likely resulting from winter storms and wildfires. However, the differences of mortality events among various species responding to the abrupt environmental changes remain poorly understood. In this study, we focused on three species, Wilson’s Warbler, Barn Owl, and Common Murre, with the highest mortality events that had been recorded by citizen scientists. We leveraged the citizen science data and multiple remotely sensed earth observations and employed the ensemble random forest models to disentangle the species responses to winter storm and wildfire. We found that the mortality events of Wilson’s Warbler were primarily impacted by early winter storms, with more deaths identified in areas with a higher average daily snow cover. The Barn Owl’s mortalities were more identified in places with severe wildfire-induced air pollution. Both winter storms and wildfire had relatively mild effects on the mortality of Common Murre, which might be more related to anomalously warm water. Our findings highlight the species-specific responses to environmental changes, which can provide significant insights into the resilience of ecosystems to environmental change and avian conservations. Additionally, the study emphasized the efficiency and effectiveness of monitoring large-scale abrupt environmental changes and conservation using remotely sensed and citizen science data.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Understanding Microbiome Stability in a Changing World

Microbiomes underpin biogeochemical processes, sustain the bases of food webs, and recycle carbon and nutrients. Hence, microbes are frontline players in determining ecosystem responses to environmental change. My research team and I investigate the causes and consequences of microbiome stability. Our primary objective is to understand the responses of complex microbiomes to stressors associated with environmental change. This work is important because Earth is changing rapidly and drastically, and these changes are expected to have serious consequences for ecosystems, their inhabiting organisms, and their microbiomes. Therefore, we aim to understand the repercussions of alterations to microbiome structure and functions and to use this information to predict the responses of microbiomes to stressors. This research is critical to prepare for, respond to, and potentially moderate environmental change. We anticipate that the results of our research will contribute toward these goals and will broadly inform management or manipulation of microbiomes toward desired functions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to characterize. However, to understand the thermodynamic and kinetic controls on greenhouse gas (carbon dioxide [CO 2 ] and methane [CH 4 ]) production resulting from the decomposition of NOM, a molecular-level characterization coupled with microbial proteome analyses is necessary. Further, climate and environmental changes are expected to perturb natural ecosystems, potentially upsetting complex interactions that influence both the supply of organic matter substrates and the microorganisms performing the transformations. A detailed molecular characterization of the organic matter, microbial proteomics, and the pathways and transformations by which organic matter is decomposed will be necessary to predict the direction and magnitude of the effects of environmental changes. This article describes a methodological throughput for comprehensive metabolite characterization in a single sample by direct injection Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), gas chromatography mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography mass spectrometry (LC-MS), and proteomics analysis. Furthermore, this approach results in a fully-paired dataset which improves statistical confidence for inferring pathways of organic matter decomposition, the resulting CO 2 and CH 4 production rates, and their responses to environmental perturbation. Herein we present results of applying this method to NOM samples collected from peatlands; however, the protocol is applicable to any NOM sample (e.g., peat, forested soils, marine sediments, etc.).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Consideration of climate change on environmental impact assessment in Spain

Most of the projects subject to environmental impact assessment (EIA) are closely related to climate change, as they contribute to or are affected by it. The growing certainty about climate change and its impacts makes its consideration an essential part of the EIA process, as well as in strategic environmental assessment (SEA). This paper examines how climate change (CC) has been taken into account in EIA in Spain through the analysis of 1713 environmental records of decision (RODs) of projects submitted for EIA. In 2013 Spain approved one of the most advanced laws in terms of CC consideration in environmental assessment, although it had not yet accumulated extensive practice on the issue. This contrasts with the situation of countries like Canada or the USA, which have a significant body of experience without specific legal requirements. Only 14% of the RODs analysed included references to CC, and in more than half of the cases it was a mere citation. Thermal power plants, which are subject to specific GHG regulations, show the highest consideration, while transport infrastructures, which are important contributors to CC, show a very low consideration. Almost all the references are related to their contribution to CC, while consideration of the effects of CC is minimal. The increasingly common incorporation of CC into SEA, should not imply its exclusion from EIA, because both processes have different aims and uses. Including the obligation to consider CC in the EIA regulations is highly desirable, but probably not enough without other measures, such as practical guidance, training and motivational programmes for practitioners and evaluators. But even these actions cannot ensure effective and adequate assessments of CC. Probably more resources should be spent on creating greater awareness in all the agents involved in EIA. - Highlights: • We analyse how the climate change is considered in EIA in Spain. • Few projects seriously assess climate change. • Transport infrastructure projects barely consider climate change. • Assessing climate change in SEA should not imply that it is excluded from EIA.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Measuring changes in environmental radiological background from construction of an advanced nuclear reactor testing facility

We present a method to survey and track changes in the environmental radiological background during the construction and operation of advanced nuclear reactor facilities. We discuss the results of two surveys of the environmental gamma-radiation background at NEXT Lab, an advanced nuclear reactor research facility on the campus of Abilene Christian University, prior to the introduction of radioactive material. In both surveys, the observed radiation dosage rates are low, with the highest rates at 15% of the average total radiation dosage rate for the United States. We observe ≈20% changes in the radiological background of the property in locations where the environment was changed by construction and ≈20% variations within the facilities correlated with variations in building materials.

Environment↗
DOE OSTI2019

Beyond Static Benchmarking: Using Experimental Manipulations to Evaluate Land Model Assumptions

Land models are often used to simulate terrestrial responses to future environmental changes, but these models are not commonly evaluated with data from experimental manipulations. Results from experimental manipulations can identify and evaluate model assumptions that are consistent with appropriate ecosystem responses to future environmental change. We conducted simulations using three coupled carbon-nitrogen versions of the Community Land Model (CLM, versions 4, 4.5, and—the newly developed—5), and compared the simulated response to nitrogen (N) and atmospheric carbon dioxide (CO 2 ) enrichment with meta-analyses of observations from similar experimental manipulations. In control simulations, successive versions of CLM showed a poleward increase in gross primary productivity and an overall bias reduction, compared to FLUXNET-MTE observations. Simulations with N and CO 2 enrichment demonstrate that CLM transitioned from a model that exhibited strong nitrogen limitation of the terrestrial carbon cycle (CLM4) to a model that showed greater responsiveness to elevated concentrations of CO 2 in the atmosphere (CLM5). Overall, CLM5 simulations showed better agreement with observed ecosystem responses to experimental N and CO 2 enrichment than previous versions of the model. These simulations also exposed shortcomings in structural assumptions and parameterizations. Specifically, no version of CLM captures changes in plant physiology, allocation, and nutrient uptake that are likely important aspects of terrestrial ecosystems' responses to environmental change. These highlight priority areas that should be addressed in future model developments. Moving forward, incorporating results from experimental manipulations into model benchmarking tools that are used to evaluate model performance will help increase confidence in terrestrial carbon cycle projections.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

How do soil microbes shape ecosystem biogeochemistry in the context of global change?

Earth system models disagree on the future of global soil carbon C, with projections ranging from losses of 70 Pg to gains of 250 Pg by the year 2100 (Todd-Brown et al., 2014). This disagreement is due, in part, to the high degree of uncertainty in the mechanisms that control soil C, the largest dynamic pool of organic C on Earth. It remains unclear how climate change, rising atmospheric CO2 levels, and other environmental changes will combine to affect global soil C. As key engineers of biogeochemical cycling, microbes play a crucial role in soil C responses to these environmental changes. Yet, the path toward representing microbes in soil models remains uncertain. Furthermore, we address four burning questions relevant for modelling microbial ecological, evolutionary, and biogeochemical processes in soils: (1) What is the role of soil microbes in biogeochemical cycling? (2) Does microbial community composition matter for soil carbon cycling? (3) Which ecological and evolutionary processes contribute to functional changes? (4) How should we model microbial eco-evolutionary mechanisms in soil C models?

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Probing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering

Direct tracking of protein structural dynamics during folding–unfolding processes is important for understanding the roles of hierarchic structural factors in the formation of functional proteins. As such, using cytochrome c (cyt c) as a platform, we investigated its structural dynamics during folding processes triggered by local environmental changes (i.e., pH or heme iron center oxidation/spin/ligation states) with time-resolved X-ray solution scattering measurements. Starting from partially unfolded cyt c, a sudden pH drop initiated by light excitation of a photoacid caused a structural contraction in microseconds, followed by active site restructuring and unfolding in milliseconds. In contrast, the reduction of iron in the heme via photoinduced electron transfer did not affect conformational stability at short timescales (<1 ms), despite active site coordination geometry changes. These results demonstrate how different environmental perturbations can change the nature of interaction between the active site and protein conformation, even within the same metalloprotein, which will subsequently affect the folding structural dynamics.

Rimmerman, Dolev↗
DOE OSTI2024

Changes in environmental and engineered conditions alter the plasma membrane lipidome of fractured shale bacteria

ABSTRACT Microorganisms that persist in fractured shale reservoirs cause several problems including secreting foul gases and forming biofilms. Current biocontrol measures often fail due to limited knowledge of their in situ activities. The plasma membrane protects the cell, mediates many of its critical functions, and responds to intracellular cues and ecological perturbations through physicochemical modifications. As such, it provides valuable insight into the physiological adaptation of microorganisms in disturbed environmental systems. Here, we (i) demonstrate how changes in salinity and hydraulic retention time (HRT) influence the plasma membrane intact polar lipid (IPL) chemistry of model bacterium, Halanaerobium congolense WG10, and mixed microbial consortia enriched from shale-produced fluids and (ii) elucidate adjustments in membrane IPL chemistry during biofilm growth relative to planktonic cells. We incubated H. congolense WG10 in chemostats under three salinities (7%, 13%, and 20% NaCl), operated under three HRTs (19.2, 24, and 48 h), and in drip flow biofilm reactors under the same salinity gradients. Also, mixed microbial consortia in produced fluids were enriched in triplicate chemostat vessels under three HRTs (19.2, 24, and 72 h) and biofilm reactors. Lipids were analyzed by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Our results show that phosphatidylglycerols, cardiolipins, and phosphatidylethanolamines were predominantly enriched in planktonic H. congolense WG10 cells grown at hypersalinity (20%) compared to optimum (13%). In addition, several zwitterionic phosphatidylcholines and phosphatidylethanolamines were higher in abundance during biofilm growth. These observations suggest that microbial adaptation and biofilm formation in fractured shale are enabled by strategic plasma membrane IPL chemistry adjustments. IMPORTANCE Microorganisms inadvertently introduced into the shale reservoir during fracturing face multiple stressors including brine-level salinities and starvation. However, some anaerobic halotolerant bacteria adapt and persist for long periods of time. They produce hydrogen sulfide, which sours the reservoir and corrodes engineering infrastructure. In addition, they form biofilms on rock matrices, which decrease shale permeability and clog fracture networks. These reduce well productivity and increase extraction costs. Under stress, microbes remodel their plasma membrane to optimize its roles in protection and mediating cellular processes such as signaling, transport, and energy metabolism. Hence, by observing changes in the membrane lipidome of model shale bacteria, Halanaerobium congolense WG10, and mixed consortia enriched from produced fluids under varying subsurface conditions and growth modes, we provide insight that advances our knowledge of the fractured shale biosystem. We also offer data-driven recommendations for improving biocontrol efficacy and the efficiency of energy recovery from unconventional formations.

03 NATURAL GAS↗
DOE OSTI2022

Root responses to elevated CO 2 , warming and irrigation in a semi-arid grassland: Integrating biomass, length and life span in a 5-year field experiment

Plant roots mediate the impacts of environmental change on ecosystems, yet knowledge of root responses to environmental change is limited because few experiments evaluate multiple environmental factors and their interactions. Inferences about root functions are also limited because root length dynamics are rarely measured. Using a 5-year experiment in a mixed-grass prairie, we report the responses of root biomass, length and life span to elevated carbon dioxide (CO 2 ), warming, elevated CO 2 and warming combined, and irrigation. Root biomass was quantified using soil cores and root length dynamics were assessed using minirhizotrons. By comparing root dynamics with published results for soil resources and above-ground productivity, we provide mechanistic insights into how climate change might impact grassland ecosystems. In the upper soil layer, 0–15 cm depth, both irrigation and elevated CO 2 alone increased total root length by twofold, but irrigation decreased root biomass and elevated CO 2 had only small positive effects on root biomass. The large positive effects of irrigation and elevated CO 2 alone on total root length were due to increases in both root length production and root life span. The increased total root length and life span under irrigation and elevated CO 2 coincided with apparent shifts from water limitation of plant growth to nitrogen limitation. Warming alone had minimal effects on root biomass, length and life span in this shallow soil layer. Warming and elevated CO 2 combined increased root biomass and total root length by c. 25%, but total root length in this treatment was lower than expected if the effects of CO 2 and warming alone were additive. Treatment effects on total root length and root life span varied with soil depth and root diameter. Synthesis. Sub-additive effects of CO 2 and warming suggest studies of elevated CO 2 alone might overestimate the future capacity of grassland root systems to acquire resources. In this mixed-grass prairie, elevated CO 2 with warming stimulated total root length and root life span in deeper soils, likely enhancing plant access to more stable pools of growth-limiting resources, including water and phosphorus. Therefore, these root responses help explain previous observations of higher, and more stable, above-ground productivity in these projected climate conditions.

59 BASIC BIOLOGICAL SCIENCES↗