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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Effects of submerged macrophytes (Elodea nuttallii) on water quality and microbial communities of largemouth bass (Micropterus salmoides) ponds

Traditional aquaculture ponds are one of the most vulnerable ecosystems; thus, ecological aquaculture is increasingly valued for its beneficial ecological properties and ecosystem services. However, little is known about ecological aquaculture of largemouth bass with submerged vegetation. Here, we designed three ecological ponds of cultured largemouth bass with submerged macrophytes (the EM group) and three ponds with traditional aquaculture (the M group) to reveal the response of water quality, and phytoplankton and bacterial communities, to submerged macrophyte bioremediation during a 90-day culture period. We observed that Cyanobacterial outbreak occurred in the M group ponds from day 7 to the end of the experiment; however, there were no Cyanobacterial blooms in the EM group ponds throughout the culture period. Compared with the M group ponds, the EM group ponds, which had submerged hydrophytes, had significantly decreased concentrations of TP, TN, and COD Mn , but significantly increased DO concentrations throughout the experimental period. Moreover, ecological aquaculture with submerged macrophytes showed strong effects on the phytoplankton and bacterial community compositions. In particular, the M group ponds had higher phytoplankton density and mainly included Cyanobacteria, whereas the EM group had lower phytoplankton density and mainly included Chlorophyta. Moreover, higher alpha diversity, as determined by Ace and Simpson index values, was detected for bacterial communities in the EM group ponds. Furthermore, PCoA clearly grouped the bacterial communities according to the two culture modes throughout the culture period. These results indicate that ecological aquaculture with submerged macrophytes can improve water quality, control Cyanobacterial blooms, and affect the diversity and composition of bacterial communities. These valuable effects seem to be beneficial and consistent to maintaining aquaculture ecosystem stability.

Nie, Zhijuan↗
DOE OSTI2024

Microbial Communities in Model Seawater-Compensated Fuel Ballast Tanks: Biodegradation and Biocorrosion Stimulated by Marine Sediments

Some naval vessels add seawater to carbon steel fuel ballast tanks to maintain stability during fuel consumption. Marine sediments often contaminate ballast tank fluids and have been implicated in stimulating fuel biodegradation and enhancing biocorrosion. The impact of the marine sediment was evaluated in model ballast tank reactors containing seawater, fuel (petroleum-F76, Fischer–Tropsch F76, or a 1:1 mixture), and carbon steel coupons. Control reactors did not receive fuel. The marine sediment was added to the reactors after 400 days and incubated for another year. Sediment addition produced higher estimated bacterial numbers and enhanced sulfate reduction. Ferrous sulfides were detected on all coupons, but pitting corrosion was only identified on coupons exposed to FT-F76. Aerobic hydrocarbon-degrading bacteria increased, and the level of dissolved iron decreased, consistent with the stimulation of aerobic hydrocarbon degradation by iron. We propose that sediments provide an inoculum of hydrocarbon-degrading microbes that are stimulated by dissolved iron released during steel corrosion. Hydrocarbon degradation provides intermediates for use by sulfate-reducing bacteria and reduces the level of fuel components inhibitory to anaerobic bacteria. The synergistic effect of dissolved iron produced by corrosion, biodegradable fuels, and iron-stimulated hydrocarbon-degrading microbes is a poorly recognized but potentially significant biocorrosion mechanism.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Elucidating the Role of Biofilm-Forming Microbial Communities in Fermentative Biohydrogen Process: An Overview

Amongst the biofuels described in the literature, biohydrogen has gained heightened attention over the past decade due to its remarkable properties. Biohydrogen is a renewable form of H 2 that can be produced under ambient conditions and at a low cost from biomass residues. Innovative approaches are continuously being applied to overcome the low process yields and pave the way for its scalability. Since the process primarily depends on the biohydrogen-producing bacteria, there is a need to acquire in-depth knowledge about the ecology of the various assemblages participating in the process, establishing effective bioaugmentation methods. This work provides an overview of the biofilm-forming communities during H 2 production by mixed cultures and the synergistic associations established by certain species during H 2 production. The strategies that enhance the growth of biofilms within the H 2 reactors are also discussed. A short section is also included, explaining techniques used for examining and studying these biofilm structures. The work concludes with some suggestions that could lead to breakthroughs in this area of research.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1985

From microbial communities to cells

The eukraotic cell, the unit of structure of protoctists, plants, fungi, and animals, is not at all homologous to prokaryotic cells. Instead the eukaryotic cell is homologous to communities of microorganisms such as those of the sulfuretum. This research is based on the hypothesis that at least four different interacting community members entered the original associations that, when stabilized, led to the emergence of eukaryotic cells. These are: (1) host nucleocytoplasm (thermoplasma like archaebacteria); (2) mitochrondria (paracoccus or bdellovibryo like respiring bacteria; and (3) plastids (cyanobacteria) and undulipodia. Tubulin like protein was found in the free living spirochete Spirochaeta bajacaliforniensis and in several other spirochetes. The amino acid sequence was to see if the spirochete protein is homologous to the tubulin of undulipodial and mitotic spindle microtubules.

Margulis, L.↗
NASA NTRS1995

The microbial community of Ophrydium versatile colonies: endosymbionts, residents, and tenants

Ophrydium versatile is a sessile peritrichous ciliate (Kingdom Protoctista, class Oligohymenophora, order Peritrichida, suborder Sessilina) that forms green, gelatinous colonies. Chlorophyll a and b impart a green color to Ophrydium masses due to 400-500 Chlorella-like endosymbionts in each peritrich. Ophrydium colonies, collected from two bog wetlands (Hawley and Leverett, Massachusetts) were analyzed for their gel inhabitants. Other protists include ciliates, mastigotes, euglenids, chlorophytes, and heliozoa. Routine constituents include from 50-100,000 Nitzschia per ml of gel and at least four other diatom genera (Navicula, Pinnularia, Gyrosigma, Cymbella) that may participate in synthesis of the gel matrix. Among the prokaryotes are filamentous and coccoid cyanobacteria, large rod-shaped bacteria, at least three types of spirochetes and one unidentified Saprospira-like organism. Endosymbiotic methanogenic bacteria, observed using fluorescence microscopy, were present in unidentified hypotrichous ciliates. Animals found inside the gel include rotifers, nematodes, and occasional copepods. The latter were observed in the water reservoir of larger Ophrydium masses. From 30-46% of incident visible radiation could be attenuated by Ophrydium green jelly masses in laboratory observations. Protargol staining was used to visualize the elongate macronuclei and small micronucleus of O. versatile zooids and symbiotic algal nuclei. Electron microscopic analysis of the wall of the Chlorella-like symbiont suggests that although the Ophrydium zooids from British Columbia harbor Chlorella vulgaris, those from Hawley Bog contain Graesiella sp. The growth habit in the photic zone and loose level of individuation of macroscopic Ophrydium masses are interpretable as extant analogs of certain Ediacaran biota: colonial protists in the Vendian fossil record.

Non-NASA Center↗
NASA NTRS2010

Psychrophilic Biomass Producers in the Trophic Chain of the Microbial Community of Lake Untersee, Antarctica

The study of photosynthetic microorganisms from the Lake Untersee samples showed dispersed distribution of phototrophs within ~80 m water column. Lake Untersee represents a unique ecosystem that experienced complete isolation: sealed by the Anuchin Glacier for many millennia. Consequently, its biocenosis has evolved over a significant period of time without exchange or external interaction with species from other environments. The major producers of organic matter in Lake Untersee are represented by phototrophic and chemolithotrophic microorganisms. This is the traditional trophic scheme for lacustrine ecosystems on Earth. Among the phototrophs, diatoms were not found, which differentiates this lake from other known ecosystems. The dominant species among phototrophs was Chlamydomonas sp. with typical morphostructure: green chloroplasts, bright red round spot, and two polar flagella near the opening. As expected, the physiology of studied phototrophs was limited by low temperature, which defined them as obligate psychrophilic microorganisms. By the quantity estimation of methanogenesis in this lake, the litho-autotrophic production of organic matter is competitive with phototrophic production. However, pure cultures of methanogens have not yet been obtained. We discuss the primary producers of organic matter and the participation of our novel psychrophilic homoacetogen into the litho-autotrophic link of biomass production in Lake Untersee.

Pikuta, Elena V.↗
NASA NTRS2022

Adaptation to environmental extremes structures functional traits in biological soil crust and hypolithic microbial communities

Biological soil crusts (biocrusts) are widespread in drylands and deserts. At the microhabitat scale, they also host hypolithic communities that live under semi-translucent stones. Both environmental niches experience exposure to extreme conditions such as high UV radiation, desiccation, temperature fluctuations, and resource limitation. However, hypolithic communities are somewhat protected from extremes relative to biocrust communities. Conditions are otherwise similar, so comparing them can answer outstanding questions regarding adaptations to environmental extremes. Using metagenomic sequencing, we assessed the functional potential of dryland soil communities and identified the functional underpinnings of ecological niche differentiation in biocrusts versus hypoliths. We also determined the effect of the anchoring photoautotroph (moss or cyanobacteria). Genes and pathways differing in abundance between biocrusts and hypoliths indicate that biocrust communities adapt to the higher levels of UV radiation, desiccation, and temperature extremes through an increased ability to repair damaged DNA, sense and respond to environmental stimuli, and interact with other community members and the environment. Intracellular competition appears to be crucial to both communities, with biocrust communities waging war using the Type VI Secretion System (T6SS) and hypoliths favoring diversity of antibiotics. The dominant primary producer had a reduced effect on community functional potential compared with niche, but an abundance of genes related to monosaccharide, amino acid, and osmoprotectant uptake in moss-dominated communities indicates reliance on resources provided to heterotrophs by mosses. Our findings indicate that functional traits in dryland communities are driven by adaptations to extremes and we identify strategies that likely enable survival in dryland ecosystems.

Biological soil crusts↗