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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Revisiting a ‘simple’ fungal metabolic pathway reveals redundancy, complexity and diversity

Next to d-glucose, the pentoses l-arabinose and d-xylose are the main monosaccharide components of plant cell wall polysaccharides and are therefore of major importance in biotechnological applications that use plant biomass as a substrate. Pentose catabolism is one of the best-studied pathways of primary metabolism of Aspergillus niger, and an initial outline of this pathway with individual enzymes covering each step of the pathway has been previously established. However, although growth on l-arabinose and/or d-xylose of most pentose catabolic pathway (PCP) single deletion mutants of A. niger has been shown to be negatively affected, it was not abolished, suggesting the involvement of additional enzymes. Detailed analysis of the single deletion mutants of the known A. niger PCP genes led to the identification of additional genes involved in the pathway. These results reveal a high level of complexity and redundancy in this pathway, emphasizing the need for a comprehensive understanding of metabolic pathways before entering metabolic engineering of such pathways for the generation of more efficient fungal cell factories.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Spray-induced gene silencing for disease control is dependent on the efficiency of pathogen RNA uptake

Recent discoveries show that fungi can take up environmental RNA, which can then silence fungal genes through environmental RNA interference. This discovery prompted the development of Spray-Induced Gene Silencing (SIGS) for plant disease management. In this study, we aimed to determine the efficacy of SIGS across a variety of eukaryotic microbes. We first examined the efficiency of RNA uptake in multiple pathogenic and non-pathogenic fungi, and an oomycete pathogen. We observed efficient double-stranded RNA (dsRNA) uptake in the fungal plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani, Aspergillus niger and Verticillium dahliae, but no uptake in Colletotrichum gloeosporioides, and weak uptake in a beneficial fungus, Trichoderma virens. For the oomycete plant pathogen, Phytophthora infestans, RNA uptake was limited and varied across different cell types and developmental stages. Topical application of dsRNA targeting virulence-related genes in pathogens with high RNA uptake efficiency significantly inhibited plant disease symptoms, whereas the application of dsRNA in pathogens with low RNA uptake efficiency did not suppress infection. Our results have revealed that dsRNA uptake efficiencies vary across eukaryotic microbe species and cell types. The success of SIGS for plant disease management can largely be determined by the pathogen's RNA uptake efficiency.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Lipo-Chitooligosaccharides Induce Specialized Fungal Metabolite Profiles That Modulate Bacterial Growth

Lipo-chitooligosaccharides (LCOs) are historically known for their role as microbial-derived signaling molecules that shape plant symbiosis with beneficial rhizobia or mycorrhizal fungi. Recent studies showing that LCOs are widespread across the fungal kingdom have raised questions about the ecological function of these compounds in organisms that do not form symbiotic relationships with plants. To elucidate the ecological function of these compounds, we investigate the metabolomic response of the ubiquitous human pathogen Aspergillus fumigatus to LCOs. Our metabolomics data revealed that exogenous application of various types of LCOs to A. fumigatus resulted in significant shifts in the fungal metabolic profile, with marked changes in the production of specialized metabolites known to mediate ecological interactions. Using network analyses, we identify specific types of LCOs with the most significant effect on the abundance of known metabolites. Extracts of several LCO-induced metabolic profiles significantly impact the growth rates of diverse bacterial species. These findings suggest that LCOs may play an important role in the competitive dynamics of non-plant-symbiotic fungi and bacteria. This study identifies specific metabolomic profiles induced by these ubiquitously produced chemicals and creates a foundation for future studies into the potential roles of LCOs as modulators of interkingdom competition.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Rapid and robust squashed spore/colony PCR of industrially important fungi

Fungi have been utilized for centuries in medical, agricultural, and industrial applications. Development of systems biology techniques has enabled the design and metabolic engineering of these fungi to produce novel fuels, chemicals, and enzymes from renewable feedstocks. Many genetic tools have been developed for manipulating the genome and creating mutants rapidly. However, screening and confirmation of transformants remain an inefficient step within the design, build, test, and learn cycle in many industrial fungi because extracting fungal genomic DNA is laborious, time-consuming, and involves toxic chemicals. In this study we developed a rapid and robust technique called “Squash-PCR” to break open the spores and release fungal genomic DNA as a template for PCR. The efficacy of Squash-PCR was investigated in eleven different filamentous fungal strains. Clean PCR products with high yields were achieved in all tested fungi. Spore age and type of DNA polymerase did not affect the efficiency of Squash-PCR. However, spore concentration was found to be the crucial factor for Squash-PCR in Aspergillus niger, with the dilution of starting material often resulting in higher PCR product yield. We then further evaluated the applicability of the squashing procedure for nine different yeast strains. We found that Squash-PCR can be used to improve the quality and yield of colony PCR in comparison to direct colony PCR in the tested yeast strains. The developed technique will enhance the efficiency of screening transformants and accelerate genetic engineering in filamentous fungi and yeast.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Septins coordinate cell wall integrity and lipid metabolism in a sphingolipid-dependent process

ABSTRACT Septins colocalize with membrane sterol-rich regions and facilitate recruitment of cell wall synthases during wall remodeling. We show that null mutants missing an Aspergillus nidulans core septin present in hexamers and octamers (ΔaspAcdc11, ΔaspBcdc3 or ΔaspCcdc12) are sensitive to multiple cell wall-disturbing agents that activate the cell wall integrity MAPK pathway. The null mutant missing the octamer-exclusive core septin (ΔaspDcdc10) showed similar sensitivity, but only to a single cell wall-disturbing agent and the null mutant missing the noncore septin (ΔaspE) showed only very mild sensitivity to a different single agent. Core septin mutants showed changes in wall polysaccharide composition and chitin synthase localization. Mutants missing any of the five septins resisted ergosterol-disrupting agents. Hexamer mutants showed increased sensitivity to sphingolipid-disrupting agents. Core septins mislocalized after treatment with sphingolipid-disrupting agents, but not after ergosterol-disrupting agents. Our data suggest that the core septins are involved in cell wall integrity signaling, that all five septins are involved in monitoring ergosterol metabolism, that the hexamer septins are required for sphingolipid metabolism and that septins require sphingolipids to coordinate the cell wall integrity response.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Dataset for "A Microfluidic Spore Chamber for Long-Term Imaging of Single-Spore Hyphal Development"

Understanding the life cycle of fungal spores is essential for elucidating their roles in pathogenesis, dispersal, and survival. However, studying spore development under controlled, spatially defined conditions remains challenging. Here, we present the Spore Chamber, a custom-built microfluidic platform engineered for parallel trapping and long-term imaging of individual spores under defined media conditions, enabling real-time visualization of hyphal development. Using Aspergillus fumigatus as a model organism, we demonstrate that sparse trapping of individual spores within size-matched trap geometries enables long-term time-lapse imaging of key developmental stages, including germination, polarized hyphal elongation, branching, and conidiophore formation. To assess the device’s capacity to resolve morphogenetic responses to exogenous signals, we introduced lipochitooligosaccharides (LCOs) and short-chain chitooligosaccharides (COs). Rhizobium-derived, non-sulfated LCO (nsLCO) mixtures induced enhanced secondary branching (hyperbranching), a response not previously reported in A. fumigatus under these signal conditions, to our knowledge, whereas sulfated LCOs and CO4 did not significantly alter branching patterns. In addition, long-term confinement and imaging revealed rare developmental morphologies previously described primarily in mutant strains, including split conidiophore formation, elongated phialides, microcyclic conidiation, and chlamydospore development. Together, these results establish the Spore Chamber as a targeted microfluidic platform for single-spore phenotyping and long-term developmental analysis, with applications in fungal biology, chemical signaling studies, and host–microbe interaction research. Videos of the observed phenomena are included in this data set.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Characterization of a broadly specific cadaverine N-hydroxylase involved in desferrioxamine B biosynthesis in Streptomyces sviceus

N-hydroxylating flavin-dependent monooxygenases (FMOs) are involved in the biosynthesis of hydroxamate siderophores, playing a key role in microbial virulence. Herein, we report the first structural and kinetic characterization of a novel alkyl diamine N-hydroxylase DesB from Streptomyces sviceus (SsDesB). This enzyme catalyzes the first committed step in the biosynthesis of desferrioxamine B, a clinical drug used to treat iron overload disorders. X-ray crystal structures of the SsDesB holoenzyme with FAD and the ternary complex with bound NADP + were solved at 2.86 Å and 2.37 Å resolution, respectively, providing a structural view of the active site environment. SsDesB crystallized as a tetramer and the structure of the individual protomers closely resembles the structures of homologous N-hydroxylating FMOs from Erwinia amylovora (DfoA), Pseudomonas aeruginosa (PvdA), and Aspergillus fumigatus (SidA). Using NADPH oxidation, oxygen consumption, and product formation assays, kinetic parameters were determined for various substrates with SsDesB. SsDesB exhibited typical saturation kinetics with substrate inhibition at high concentrations of NAD(P)H as well as cadaverine. The apparent k cat values for NADPH in steady-state NADPH oxidation and oxygen consumption assays were 0.28 ± 0.01 s -1 and 0.24 ± 0.01 s -1 , respectively. However, in product formation assays used to measure the rate of N-hydroxylation, the apparent k cat for NADPH (0.034 ± 0.008 s -1 ) was almost 10-fold lower under saturating FAD and cadaverine concentrations, reflecting an uncoupled reaction, and the apparent NADPH K M was 33 ± 24 μM. Under saturating FAD and NADPH concentrations, the apparent k cat and K M for cadaverine in Csaky assays were 0.048 ± 0.004 s -1 and 19 ± 9 μM, respectively. SsDesB also N-hydroxylated putrescine, spermidine, and L-lysine substrates but not alkyl (di)amines that were branched or had fewer than four methylene units in an alkyl chain. These data demonstrate that SsDesB has wider substrate scope compared to other well-studied ornithine and lysine N-hydroxylases, making it an amenable biocatalyst for the production of desferrioxamine B, derivatives, and other N-substituted products.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Biosynthesis of Zinc Oxide Nanoparticles using Fungal Filtrates

Fungi produce and excrete various proteins, enzymes, and polysaccharides, which may be used for the synthesis of nanoparticles. This study investigated the effect an anion species on the synthesis of ceramic nanoparticles using fungal filtrates. In this work, ceramic zinc oxide (ZnO) nanoparticles ranging between 1 nm and 1000 nm were successfully synthesized using three different filamentous fungi: Aspergillus sp., Penicillium sp., and Paecilomyces variotti. Each fungus was cultured, and the filtrate was extracted and individually exposed to zinc nitrate, zinc sulfate, or zinc chloride. The formation of nanoparticles was characterized using UV-visible spectrophotometry (UV-Vis), fluorescence microscopy, and with transmission electron microscopy (TEM) analyses. UV-Vis spectra exhibited broad increases in the absorption across the range of 200 nm - 800 nm, which corresponded to the formation of ZnO nanoparticles under various conditions. Nanoparticle formation was confirmed with fluorescence microscopy and TEM analysis and determined to form particles with an irregular spherical shape. To date, our work demonstrates that the ability of fungi to synthesize ZnO nanoparticles is not genus/species-specific but is dependent on the starting composition of a given metal salt.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Enhancing organic matter removal, product recovery, and hydrogen generation from fermentation wastewater

Existing ethanol biorefineries produce billions of gallons of wastewater (stillage) that must be treated extensively prior to discharge or concentrated in an energy intense evaporation step to produce animal feed as a value-added bioproduct. Yeasts and filamentous fungi were screened for growth and reduction of soluble organic compounds, carbohydrates, and protein from stillage to identify species capable of rapidly concentrating organic compounds into readily separable biomass in an attempt to concentrate the product using a much more efficient centrifugation step. Yeasts amenable to production of biomass derived products including bio-oils (Yarrowia lipolytica and Rhodotorula pallida), chitosan (Aspergillus niger) and animal feed (Cyberlindnera jadinii) were identified as well as microbes capable of efficient production of small organic acids with applications as bioderived polymers including 3-hydroxypropionic acid (engineered A. niger) and lactic acid using a co-culture of Debaryomyces udenii and Lactobacillus pentosus. The filamentous fungus A. niger eliminated all specifically measured soluble organics (glycerol, acetate, lactate, ethanol, and citrate) in under 48 hours and reduced total soluble protein content by 46% and total carbohydrate content by 83% within 96 hours, the greatest reduction in organic content observed. During this process an A. niger strain engineered to produce 3-hydroxypropionic acid achieved a yield of 0.35 C-mol 3HP / C-mol non-protein organics consumed at an overall rate of 0.09 g/Lh in unmodified stillage without pH control. Stillage treated by the fodder yeast C. jadinii as well as stillage containing acetic or lactic acid was found to be most suitable for growth by electrogenic bacteria with applications in production of electricity or hydrogen from wastewater. This work establishes fungal and bacterial strains appropriate for biological treatment of stillage to produce biomass derived products, soluble commodity chemicals, energy, and treated water to reduce the energy intensity and improve the economics of ethanol biorefineries.

09 BIOMASS FUELS↗
DOE OSTI2024

Understanding Radiotropism in Filamentous Fungi

Melanized species of filamentous fungi isolated from high radiation environments have been reported to exhibit radiotropism, defined as the directed growth toward a source of ionizing radiation. Inconsistencies in the experimental approaches and results have impeded our understanding of the key factors involved in radiotropism. In the present study, we assessed radiotropism in four isolates of fungi: Aspergillus niger, A. calidoustus JC-1043, Paecilomyces variotii SNL-1, and P. variotii IMV-00236. Of these fungi, only P. variotii IMV-00236 had been previously reported to exhibit radiotropic behavior. Plates of each fungus were placed in equivalent proximity to a 137 Cs source, with a primary gamma emission of 662 keV, and differences in the rate and direction of mycelia growth were measured over a seven-day period. Significant differences were not observed in the rate or direction of growth of the different fungi based on exposure to gamma radiation, which suggested a lack of measurable radiotropism in these experiments. Additional studies varying parameters such gamma emission rates and energies, as well as other types of ionizing radiation (e.g., alpha and beta particles, neutrons) are necessary to gain further insights to the factors critical to the expression of radiotropic behavior in filamentous fungi.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Engineering Anti-Microbial Peptide Production in Fungi and Bioprocess Development (CRADA 502)

Crop Protection, specifically controlling agricultural diseases and pests, is essential for crop production at every agricultural scale. Biologics hold enormous potential in this equation to decrease use of more toxic pesticides. Currently, the widespread use of biologics in crop protection is severely hampered by the lack of available tools for their mass production. To ensure biologics are regulated under EPA Biopesticide regulations, the following must be true: The biopesticide is a naturally occurring substance or structurally similar and functionally identical to a naturally occurring substance with a history of exposure to humans and the environment demonstrating minimal toxicity. Since this pertains to the marketed product it is also essential that fermentation hosts have a history of exposure and safe use by humans This research focuses on developing a novel platform for the production and delivery of the cghSAMP peptide using the filamentous fungus Aspergillus niger. A. niger is a well-established industrial microorganism, widely recognized for its strong protein secretion capabilities, high-yield production of enzymes, and classification as a generally recognized as safe (GRAS) organism. By genetically modifying A. niger to express the cghSAMP peptide transgene, we aim to leverage the fungus's robust fermentation system to produce a high volume of the antimicrobial agent. This engineered system represents a potential breakthrough in sustainable disease management, offering an environmentally friendly method for localized application or large-scale production of a biopesticide designed to mitigate the effects of citrus greening disease. The main objectives of this project were: 1. Developing a high-yield and cost-efficient bioprocess to produce an AMP in a current ABF host or readily onboarded hosts. 2. Scale up the process in stirred tank reactors and produce at least 100 grams of AMP at 1- 5g/L

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Investigation of microorganisms in cannabis after heating in a commercial vaporizer

There are concerns about microorganisms present on cannabis materials used in clinical settings by individuals whose health status is already compromised and are likely more susceptible to opportunistic infections from microbial populations present on the materials. Most concerning is administration by inhalation where cannabis plant material is heated in a vaporizer, aerosolized, and inhaled to receive the bioactive ingredients. Heating to high temperatures is known to kill microorganisms including bacteria and fungi; however, microbial death is dependent upon exposure time and temperature. It is unknown whether the heating of cannabis at temperatures and times designated by a commercial vaporizer utilized in clinical settings will significantly decrease the microbial loads in cannabis plant material. To assess this question, bulk cannabis plant material supplied by National Institute on Drug Abuse (NIDA) was used to assess the impact of heating by a commercial vaporizer. Initial method development studies using a cannabis placebo spiked with Escherichia coli were performed to optimize culture and recovery parameters. Subsequent studies were carried out using the cannabis placebo, low delta-9 tetrahydrocannabinol (THC) potency and high THC potency cannabis materials exposed to either no heat or heating for 30 or 70 seconds at 190°C. Phosphate-buffered saline was added to the samples and the samples agitated to suspend the microorganism. Microbial growth after no heat or heating was evaluated by plating on growth media and determining the total aerobic microbial counts and total yeast and mold counts. Overall, while there were trends of reductions in microbial counts with heating, these reductions were not statistically significant, indicating that heating using standard vaporization parameters of 70 seconds at 190°C may not eliminate the existing microbial bioburden, including any opportunistic pathogens. When cultured organisms were identified by DNA sequence analyses, several fungal and bacterial taxa were detected in the different products that have been associated with opportunistic infections or allergic reactions including Enterobacteriaceae, Staphylococcus, Pseudomonas, and Aspergillus.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Maize Terpene Synthase 8 (ZmTPS8) Contributes to a Complex Blend of Fungal-Elicited Antibiotics

In maize (Zea mays), fungal-elicited immune responses include the accumulation of terpene synthase (TPS) and cytochrome P450 monooxygenases (CYP) enzymes resulting in complex antibiotic arrays of sesquiterpenoids and diterpenoids, including α/β-selinene derivatives, zealexins, kauralexins and dolabralexins. To uncover additional antibiotic families, we conducted metabolic profiling of elicited stem tissues in mapping populations, which included B73 × M162W recombinant inbred lines and the Goodman diversity panel. Five candidate sesquiterpenoids associated with a chromosome 1 locus spanning the location of ZmTPS27 and ZmTPS8. Heterologous enzyme co-expression studies of ZmTPS27 in Nicotiana benthamiana resulted in geraniol production while ZmTPS8 yielded α-copaene, δ-cadinene and sesquiterpene alcohols consistent with epi-cubebol, cubebol, copan-3-ol and copaborneol matching the association mapping efforts. ZmTPS8 is an established multiproduct α-copaene synthase; however, ZmTPS8-derived sesquiterpene alcohols are rarely encountered in maize tissues. A genome wide association study further linked an unknown sesquiterpene acid to ZmTPS8 and combined ZmTPS8-ZmCYP71Z19 heterologous enzyme co-expression studies yielded the same product. To consider defensive roles for ZmTPS8, in vitro bioassays with cubebol demonstrated significant antifungal activity against both Fusarium graminearum and Aspergillus parasiticus. As a genetically variable biochemical trait, ZmTPS8 contributes to the cocktail of terpenoid antibiotics present following complex interactions between wounding and fungal elicitation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Post-Synthetic Reduction of Pectin Methylesterification Causes Morphological Abnormalities and Alterations to Stress Response in Arabidopsis thaliana

Pectin is a critical component of the plant cell wall, supporting wall biomechanics and contributing to cell wall signaling in response to stress. The plant cell carefully regulates pectin methylesterification with endogenous pectin methylesterases (PMEs) and their inhibitors (PMEIs) to promote growth and protect against pathogens. We expressed Aspergillus nidulans pectin methylesterase (AnPME) in Arabidopsis thaliana plants to determine the impacts of methylesterification status on pectin function. Plants expressing AnPME had a roughly 50% reduction in methylester content compared with control plants. AnPME plants displayed a severe dwarf phenotype, including small, bushy rosettes and shorter roots. This phenotype was caused by a reduction in cell elongation. Cell wall composition was altered in AnPME plants, with significantly more arabinose and significantly less galacturonic acid, suggesting that plants actively monitor and compensate for altered pectin content. Cell walls of AnPME plants were more readily degraded by polygalacturonase (PG) alone but were less susceptible to treatment with a mixture of PG and PME. AnPME plants were insensitive to osmotic stress, and their susceptibility to Botrytis cinerea was comparable to wild type plants despite their compromised cell walls. This is likely due to upregulated expression of defense response genes observed in AnPME plants. These results demonstrate the importance of pectin in both normal growth and development, and in response to biotic and abiotic stresses.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

In Vivo Entombment of Bacteria and Fungi during Calcium Oxalate, Brushite, and Struvite Urolithiasis

Human kidney stones form via repeated events of mineral precipitation, partial dissolution, and reprecipitation, which are directly analogous to similar processes in other natural and manmade environments, where resident microbiomes strongly influence biomineralization. High-resolution microscopy and high-fidelity metagenomic (microscopy-to-omics) analyses, applicable to all forms of biomineralization, have been applied to assemble definitive evidence of in vivo microbiome entombment during urolithiasis. Stone fragments were collected from a randomly chosen cohort of 20 patients using standard percutaneous nephrolithotomy (PCNL). Fourier transform infrared (FTIR) spectroscopy indicated that 18 of these patients were calcium oxalate (CaOx) stone formers, whereas one patient formed each formed brushite and struvite stones. This apportionment is consistent with global stone mineralogy distributions. Stone fragments from seven of these 20 patients (five CaOx, one brushite, and one struvite) were thin sectioned and analyzed using brightfield (BF), polarization (POL), confocal, super-resolution autofluorescence (SRAF), and Raman techniques. DNA from remaining fragments, grouped according to each of the 20 patients, were analyzed with amplicon sequencing of 16S rRNA gene sequences (V1–V3, V3–V5) and internal transcribed spacer (ITS1, ITS2) regions. Bulk-entombed DNA was sequenced from stone fragments in 11 of the 18 patients who formed CaOx stones, and the patients who formed brushite and struvite stones. These analyses confirmed the presence of an entombed low-diversity community of bacteria and fungi, including Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Aspergillus niger. Bacterial cells approximately 1 μm in diameter were also optically observed to be entombed and well preserved in amorphous hydroxyapatite spherules and fans of needle-like crystals of brushite and struvite. In conclusion, these results indicate a microbiome is entombed during in vivo CaOx stone formation. Similar processes are implied for brushite and struvite stones. This evidence lays the groundwork for future in vitro and in vivo experimentation to determine how the microbiome may actively and/or passively influence kidney stone biomineralization.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1972

Analysis of fungal type isolates taken from a 90-day manned test of an advanced regenerative life support system

Fungal-like cultures isolated before, during, and after the 90-day test from samples of space station simulator (SSS) atmosphere, surfaces, subsystem componets, and crew dermal sites were identified to genus. Out of the original 525 isolates, approximately 80% were classified as bacteria. Laboratory methods (culture media, moisturization, and incubation temperatures) favored the recovery of medically significant bacteria rather than fungi. Therefore, fungal isolates were mostly, nonfastidious types which are ubiquitous in soil and air and commonly contaminate laboratory cultures of pathogens. Predominant isolates were species of Aspergillus, Penicillium, Pullularia, Rhodotorula, and various yeasts. No instances of fungal proliferation were observed; test data reflect the survival of environmental types indigenous to the SSS pretests.

Sofios, M.↗
NASA NTRS1978

Growth of fungi in NaCl-MgSO4 brines

Previous investigations have shown that common fungi of the Penicillium-Aspergillus group can be grown in a variety of brines or on moist salt crystals. This simulates salt flats as well as sizeable waterbodies stabilized as saturated brines such as Don Juan Pond (Antarctica), the Great Salt Lake of Utah, and the Dead Sea in the Jordan Valley. In general, salt media rich in KCl are favored over other alkali halides; the media become more selective as the salt concentration rises and nutrient requirements become more complex. In the present paper, it is shown that media which resemble the Dead Sea salt mix can, in fact, support the growth of selected fungal strains, even in the absence of reduced organic nutrients other than glucose. Such media may serve as models for localized microhabitats on Mars.

Siegel, S. M.↗
NASA NTRS1990

Use of inedible wheat residues from the KSC-CELSS breadboard facility for production of fungal cellulase

Cellulose and xylan (a hemicellulose) comprise 50 percent of inedible wheat residue (which is 60 percent of total wheat biomass) produced in the Kennedy Space Center Closed Ecological Life Support System (CELSS) Breadboard Biomass Production Chamber (BPC). These polysaccharides can be converted by enzymatic hydrolysis into useful monosaccharides, thus maximizing the use of BPC volume and energy, and minimizing waste material to be treated. The evaluation of CELSS-derived wheat residues for production for cellulase enzyme complex by Trichoderma reesei and supplemental beta-glucosidase by Aspergillus phoenicis is in progress. Results to date are given.

Strayer, R. F.↗