26 Search Results

Large scale commercial cultivation of microalgae year-round is limited by seasonal stress conditions. The rapid growth and high CO2 capture of the marine microalga Picochlorum celeri is largely inhibited under winter stress conditions of low temperature and high light. Herein, we demonstrated a nanotechnology approach to enhance the biomass productivity and CO2 capture of P. celeri under abiotic stress by interfacing with antioxidant cerium oxide nanozymes (nanoceria). Antioxidant nanoceria catalytically scavenged reactive oxygen species (ROS) generated under stress conditions, reducing damage to the microalgae photosynthetic machinery in chloroplasts. Negatively charged poly-acrylic acid-coated nanoceria (PNC, 10 ..mu..M) were biocompatible in microalgaemore » cells and colocalized with chloroplasts. In contrast, positively charged aminated nanoceria (ANC) resulted in microalgae aggregation (>50 ..mu..M) and were toxic at all concentrations tested (>=10 ..mu..M). PNC reduction of ROS levels in microalgae (78%) and superoxide levels (26%), enhanced microalgae growth (65%), photosynthetic performance (130%), and CO2 uptake rate (380%) under low-temperature stress (15 degrees C) and high light (500 ..mu..mol/m2/s PAR) stress relative to controls without nanoceria. Nanoceria augmentation of microalgae provides a rapid and facile technology to increase algae CO2 capture and biomass under stress conditions.« less

A multifaceted separations platform that incorporates the strengths of asymmetrical flow field-flow fractionation with multi-detectors (AF4-MD), high performance anion exchange chromatography (HPAEC), and hydrophilic interaction liquid chromatography with mass spectrometry (HILIC-MS) is developed to obtain a more complete picture of the molecular weights (MW), composition, and salt-induced aggregation behavior of extracellular polymeric substances (EPS) produced by the algae Chlorella vulgaris. The absence of a stationary phase makes AF4-MD particularly well suited for characterizing polydisperse hydrocolloid polymers as well as studies that investigate the effect of ionic environments that aligns with the natural environment of C. vulgaris. Fractionation of C. vulgarismore » EPS revealed three distinct MW populations ranging from 4 × 10⁴ to 3 × 10⁸ Daltons. This exceeds the previously reported MW by three orders of magnitude and reports a previously unknown size subpopulation. The optimized AF4-MD technique was then used to produce two size fractions that were probed using HPAEC and LC-MS. These orthogonal methods uncovered compositional heterogeneity across fractions, with variations in monosaccharides and amino acids. AF4-MD is also well suited for studying the behavior of EPS in the presence of different salts. For each salt studied, e.g., NaNO₃, NaCl, and MgCl₂, an increase in solution ionic strength results in aggregation as corroborated by a shift to higher MWs. Each salt exhibited distinct effects on EPS aggregation, with NaCl causing the least aggregation and MgCl₂ the most. These findings highlight the need for multiple techniques when analyzing complex polymers such as EPS and the benefits of AF4-MD in elucidating complex polymer behaviors in different ionic environments.« less

While photosynthetic algae-based systems have shown promise for reducing the carbon footprint associated with biofuel and biochemical production due higher yields than terrestrial crops, there are challenges associated with CO₂ delivery and utilization resulting from the chemical and physical environment experienced. Point-source CO₂ delivery is a critical component of intensive algal cultivation, but a significant fraction of the CO₂ sparged into the aqueous environment is lost. In this context, we review the theoretical considerations for deconvoluting carbon transfer efficiency (CTE) and carbon utilization efficiency (CUE), specifically in microalgal cultivation in response to changes in media formulation and alkalinity. We introducemore » an empirical and operational approach to increase the efficiency of CO₂ transfer and ultimately prime algal cultures for photosynthetic carbon assimilation. We define operational boundaries for improving CUE under a neutral pH regime, with conditions that maintain high algal biomass productivity. Our work supports both the implementation of strategies for increasing CUE as well as provides a framework for monitoring inorganic and organic carbon balances in controlled aqueous systems. The integration of water chemistry in media formulation with dissolved inorganic carbon (DIC) and alkalinity are primary drivers of the inorganic carbon flux from a concentrated CO₂ source towards an accessible carbon source for microalgae. We outline a systematic approach by leveraging control over carbon delivery, operational pH in the neutral pH regime, and alkalinity to match available DIC of the media with the demands of the algae to help optimize CTE and CUE. This control increases the feasibility of large-scale biotic CO₂ capture in aqueous systems.« less

Polysaccharides make up a large portion of the organic material from and in marine organisms. However, their structural characterization is often overlooked due to their complexity. With many high-value applications and unique bioactivities resulting from the polysaccharides’ complex and heterogeneous structures, dedicated analytical efforts become important to achieve structural elucidation. Because algae represent the largest marine resource of polysaccharides, the majority of the discussion is focused on well-known algae-based hydrocolloid polymers. The native environment of marine polysaccharides presents challenges to many conventional analytical techniques necessitating novel methodologies. We aim to deliver a review of the current state of the artmore » in polysaccharide characterization, focused on capabilities as well as limitations in the context of marine environments. This review covers the extraction and isolation of marine polysaccharides, in addition to characterizations from monosaccharides to secondary and tertiary structures, highlighting a suite of analytical techniques.« less

Carbon capture and biochemical storage are some of the primary drivers of photosynthetic yield and productivity. To elucidate the mechanisms governing carbon allocation, we designed a photosynthetic light response test system for genetic and metabolic carbon assimilation tracking, using microalgae as simplified plant models. The systems biology mapping of high light-responsive photophysiology and carbon utilization dynamics between two variants of the same Picochlorum celeri species, TG1 and TG2 elucidated metabolic bottlenecks and transport rates of intermediates using instationary ¹³C-fluxomics. Simultaneous global gene expression dynamics showed 73% of the annotated genes responding within one hour, elucidating a singular, diel-responsive transcription factor,more » closely related to the CCA1/LHY clock genes in plants, with significantly altered expression in TG2. Transgenic P. celeri TG1 cells expressing the TG2 CCA1/LHY gene, showed 15% increase in growth rates and 25% increase in storage carbohydrate content, supporting a coordinating regulatory function for a single transcription factor.« less

Here this work proposes and applies a sequential approach of objective methods to aid the decision-making process for the deployment of microalgae biorefineries. The strategy combines Multicriteria Decision Analysis (MCDA) and weight assignment methods to simultaneously consider technical, economic, and environmental criteria to (1) outrank the best bioproduct options from different biomass fractions present in microalgae biomass at different ratios (namely carbohydrates, lipids, and protein) and (2) define the most suitable biorefining pathways associated with specific pairings of microalgae strains and cultivation conditions. The first part of the assessment identified succinic acid, acrylic acid, and citric acid as the top-rankedmore » bioproducts from carbohydrates, polyurethane from lipids, and thermoplastic extrusion co-feed from protein. The second step of the analysis determined that, when production of a hydrocarbon fuel is desired, the compositional profile of a strain is paramount in defining the biorefining setup that should be pursued. In summary, microalgae lipids should be sent to the production of hydrocarbon fuels if the ratio between neutral lipids and fermentable carbohydrates is higher than roughly 1, with carbohydrates and protein being converted to the higher-value products noted above. Finally, this result was corroborated through process simulations, which indicated superior economic and environmental metrics when strains are paired with suitable conversion pathways identified through MCDA based on their compositional profiles. The outcomes of this work provide clear, objective, guidelines for establishing the best biorefining approach for a large suite of biochemical compositions as a screening method prior to employing detailed process simulations alongside rigorous techno-economic and life-cycle assessments.« less

Marine herbivorous fish that feed primarily on macroalgae, such as those from the genus Kyphosus, are essential for maintaining coral health and abundance on tropical reefs. Here, deep metagenomic sequencing and assembly of gut compartment-specific samples from three sympatric, macroalgivorous Hawaiian kyphosid species have been used to connect host gut microbial taxa with predicted protein functional capacities likely to contribute to efficient macroalgal digestion. Bacterial community compositions, algal dietary sources, and predicted enzyme functionalities were analyzed in parallel for 16 metagenomes spanning the mid- and hindgut digestive regions of wild-caught fishes. Gene colocalization patterns of expanded carbohydrate (CAZy) and sulfatasemore » (SulfAtlas) digestive enzyme families on assembled contigs were used to identify likely polysaccharide utilization locus associations and to visualize potential cooperative networks of extracellularly exported proteins targeting complex sulfated polysaccharides. These insights into the gut microbiota of herbivorous marine fish and their functional capabilities improve our understanding of the enzymes and microorganisms involved in digesting complex macroalgal sulfated polysaccharides.« less

Elucidating intra-organismal biochemical and lipid organization in photosynthetic biological cell factories of filamentous cyanobacteria, i.e., Arthrospira platensis (Spirulina), is important to track physiological response mechanisms during growth. Little is known about the filaments' biochemical organization and cellular structure and no label-free imaging techniques exist that provide molecular mapping. We applied ultra-high resolution mass spectrometry (7T FT-ICR-MS) matrix-assisted laser desorption ionization (MALDI) imaging to immobilized Spirulina filaments to investigate the localization of lipids across distinct physiological regions. We optimized matrix selection and deposition methods with the goal of facilitating high spatial, and intra-filament, resolution using untargeted multivariate statistical spectral deconvolution acrossmore » MS pixels. Our results demonstrate an improved two step application with an optimized procedure for intra-organismal lipid profiling to improve analyte sensitivity and achieve higher spatial resolution, whereby we evaluate three conventional matrices 2,5-dihydroxybenzoic acid (DHB), a 9:1 ratio of DHB:superDHB (sDHB), 1,5- diaminonaphthalene (DAN) and a 50:50 mix of DHB:sDHB and compare delineation and pixel-based elucidation of intra-filament lipidomics. We identified a total of 1,626 features that could be putatively assigned a lipid-like formula based on database query and 46 unique features, with associated lipid assignments that were significantly distinct in their intra-filament location. MALDI- imaging MS with untargeted statistical spectral deconvolution was used to visualize intra-filament lipidomics organization in Spirulina filaments. Improvements in matrix deposition, including sequential sublimation and pneumatic spraying, increased signal abundance at high spatial resolution and allowed for identification of distinct lipid composition regions. Here in this work outlines a methodology that may be used for micro-ecological untargeted molecular phenotyping.« less

The Development of Integrated Screening, Cultivar Optimization, and Verification Research (DISCOVR) collaborative consortium operated pre-pilot scale outdoor ponds to deliver much-needed multi-year, long-term and consistent, algae cultivation data relevant to understanding the current state of technology in terms of expected seasonal algae biomass productivity. Over the course of four years from 2018 to 2021, twelve identical 4.2 m² mini-ponds were run in triplicate sets to test strains and operational strategies demonstrated in small-, indoor photobioreactors, in pursuit of increasing overall algae areal productivity and projected farm yield. Fourteen different cultivars derived from a strain screening pipeline were tested. Through deliberatemore » seasonal crop rotation and improvements in operational strategies, annual biomass productivity increased from 11.6 to 17.6 g m^-2 day^-1, a > 50% increase over the 2018 baseline. Both brackish and marine strains were included and four out of the fourteen strains consistently yielded high productivity across multiple years; brackish strains Monoraphidium minutum (26BAM) and Scenedesmus obliquus (UTEX393), and marine strains Tetraselmis striata (LANL1001) and Picochlorum celeri (TG2). These freely available datasets, which represent nearly complete annual daily coverage of cultivation metrics including weather, pond temperature and pH, nutrients, and productivity, are unique in the public domain and seek to fill agronomic and operational knowledge gaps to help in the eventual commercialization of algal biofuels and bioproducts.« less

To address major knowledge gaps and barriers to the commercial development of algal biomass for biofuels and co-products, a collaborative consortium, Development of Integrated Screening, Cultivar Optimization, and Verification Research (DISCOVR), was established in 2016. Funded by the U.S. Department of Energy (DOE) Bioenergy Technologies Office (BETO), this consortium constitutes a partnership between four DOE national laboratories - Pacific Northwest National Laboratory (PNNL), Los Alamos National Laboratory (LANL), the National Renewable Energy Laboratory (NREL), and Sandia National Laboratories (SNL) - and the Arizona Center for Algae Technology and Innovation (AzCATI) at Arizona State University. To address the barriers of strainmore » selection for achieving high seasonal productivities with a suitable composition and culture resilience, a tiered strain down-selection pipeline is implemented. At Tier I, the temperature and salinity tolerance of strains is determined in flask cultures; at Tier II, the areal biomass productivity and composition is determined in climate-simulation photobioreactors; at Tier III, the productivity and culture stability are determined in outdoor raceways. The top performing strains move forward to long-term testing at the algae testbed site at AzCATI to generate annual biomass productivity data. Concurrent to the strain down-selection in the DISCOVR pipeline, hypotheses for increasing biomass productivity, shifting biomass composition to enhance intrinsic value, and improving culture stability and resistance to pests are also tested. Techno-economic analyses are carried out to determine whether promising findings from laboratory studies or proposed modifications in outdoor pond cultivation conditions translate into reductions in the minimum biomass selling price (MBSP). Notably, in the three years following the launch of DISCOVR, annual biomass productivity has increased from 11.7 to 17.6 g m^-2 day^-1, resulting in an MBSP decrease from 824 to 611 $ ton^-1.« less