Nanoscale STXM imaging of soil fungal exudates and organo-mineral interfaces

2020 ◽  
Author(s):  
Milda Pucetaite ◽  
Per Persson ◽  
Edith Hammer
Keyword(s):  
Light Source ◽  
Soil Aggregates ◽  
Decisive Role ◽  
Arbuscular Mycorrhizal ◽  
Fungal Hypha ◽  
Organic C ◽  
X Ray ◽  
Mineral Particles ◽  
Silicon Nitride Membrane ◽  
Mineral Interfaces

<p>Soils act as a major sink for atmospheric carbon (C) and, correctly managed, can help counterbalance the excessive CO<sub>2</sub> emissions. Organic C in soils can be physically stabilized and ‘hidden’ from its decomposers within soil aggregates and it is thought that soil fungi play a decisive role in “gluing together” and redistributing soil mineral particles and existing organic matter to form them (M. W. I. Schmidt et al., Nature 478(7367), 49–56, 2011). A significant contribution to the early aggregation process is adsorption of fungal exudates to the reactive surfaces of mineral particles. To uncover the mechanisms of C stabilization processes and to be able to increase the C sink potential of our soils, we need a deepened understanding of which fungi play key roles in the process, what mineral properties promote it, and what type of fungal exudates are involved.</p><p>For this purpose, we have grown saprotrophic and symbiotic (both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM)) fungi under sterile conditions in contact with different principal soil components: quartz, goethite and muscovite, on top of X-ray transparent silicon nitride membrane windows and analyzed fungal hyphae by high lateral resolution synchrotron based scanning transmission X-ray microscopy (STXM) in combination with near edge X-ray fine structure (NEXAFS) spectroscopy at absorption edges of C(K), K(L), N(K) and Fe(L). We performed our experiments in the SM beamline at Canadian Light Source, Saskatoon, Canada and I08 beamline at Diamond Light Source, Oxfordshire, UK. In the resultant chemical images, we were able to differentiate the mostly proteinaceous hyphal material, the exudate layer constituting of mixtures of polysaccharides and proteins, and the organo-mineral interfaces consisting of a higher protein and carboxyl to sugar ratio than in the exudate layer. We also observed heterogeneous distributions of the exudate materials around the fungal hypha, indicating presence of exudation channels in the cell wall. Finally, we specifically analyzed NEXAFS spectra at Fe(L) absorption edge of goethite containing samples and were able to show changes in iron speciation in the mineral particles that were in contact with the fungal exudates. These results provide us with better insights to both nanoscale processes of fungal exudation and their role in the formation of organo-mineral interfaces subsequently responsible for soil aggregation.</p>

scholarly journals Soil aggregation dynamics and carbon sequestration

2013 ◽  
Vol 5 (1) ◽  
pp. 250-267 ◽  
Author(s):  
Rakesh Kumar ◽  
Kisan Singh Rawat ◽  
Jitendra Singh ◽  
Ashutosh Singh ◽  
Ashish Rai
Keyword(s):  
Soil Aggregates ◽  
Plant Roots ◽  
Bacterial Cells ◽  
Natural Ecosystems ◽  
Soil System ◽  
Organic C ◽  
Inorganic Particles ◽  
X Ray ◽  
Aggregate Fractions ◽  
Stability Dynamics

The quantity and quality of residues determine the formation and stabilization of aggregate structure for soil organic carbon (SOC) sequestration. Plant roots and residues are the primary organic skeleton to enmesh the inorganic particles together and build macro- and microaggregates while sequestering SOC. There are three major organic binding agents of aggregation: temporary (plant roots, fungal hyphae, and bacterial cells), transient (polysaccharides), and persistent (humic compounds and polymers). Conversion of natural ecosystems into agricultural lands for intensive cultivation severely depletes SOC pools. Magnitude of SOC sequestration in the soil system depends on the residence time of SOC in aggregates. Microaggregates are bound to old organic C, whereas macroaggregates contain younger organic material. Many techniques have been used to assess the SOC distribution in aggregates. Classical methods include SOC determination in aggregate fractions by wet and dry sieving of bulk soil. Isotopic methods including the determination of 13C and 14C with mass spectrometry are techniques to quantify the turnover and storage of organic materials in soil aggregates. Other techniques involve the use of computed tomography, X-ray scattering, and X-ray microscopy to examine the internal porosity and interaggregate attributes of macro- and microaggregates. Current state-of-knowledge has not unravelled completely the underlying complex processes involved in the sequestration, stability, dynamics, and residence times of SOC in macro- and microaggregates. There is a need to develop a unique conceptual model of aggregate hierarchy.

Arbuscular Mycorrhizal symbiosis enhances aggregate formation and organic matter sequestration in alkaline Fe ore tailings

2021 ◽  
Author(s):  
Zhen Li ◽  
Songlin Wu ◽  
Longbin Huang
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Aggregate Formation ◽  
Organic C ◽  
Mineral Particles ◽  
Am Symbiosis ◽  
C And N

<p>Alkaline Fe ore tailings are by far one of the most challenging environmental issue facing the global mining industry, which is ranked 4<sup>th</sup> globally in terms of their discharge volumes in storage dams. These tailings possess poor physical structures and adverse chemical properties (e.g., alkaline pH and deficiencies of organic carbon and nutrients) and it is hard for sustainable colonization of plants and microbial communities. Eco-engineering tailings into soil-like substrate in situ is a promising technology to achieve sustainable rehabilitation of tailing landscape. The formation of water stable aggregates (WSA) in tailings primed with eco-engineering inpiuts (e.g., plant biomass organic matter and fertilisers) is indicative of the first milestone of soil formaiton, resulting from bio-geochemically driven mineral weathering and cementation. WSAs are basic physical units underpinning soil structure and functions, such as the porosity and hydraulic conductivity, gas exchange and water retention, biological activities of microbes and roots. The further development and evolution may be enhanced by Arbuscular mycorrhizal (AM) fungi associated with plants colonising infertile soil (such as tailing-soil), because of their role in generating organic cements and organo-mineral interactions. Our previous study found that AM fungi were present in the Fe ore mine tailing site, associated with colonising native plants. In the present study, we have investigated the role of AM symbiosis (Glomus spp. in association with Sorghum spp.) in aggregate formation and organic matter sequestration in Fe ore tailings eco-engineered with organic matter amendment and pioneer plant colonization. The results showed that AM fungi formed symbiotic association with Sorghum spp. plant roots (with mycorrhizal colonization intensity above 80%) in the eco-engineered tailings. Quantitatively, AM symbiosis enhanced the formation of micro-aggregates (53~250 um) rather than macro-aggregate aggregates (250 um~2000 um) formation, which may be partially due to the direct role of extra-radical mycelium as revealed by FE-SEM analysis. Qualitatively, AM symbiosis increased the amount of organic carbon and nitrogen associated with mineral particles in the macro-aggregates. Those organic carbon associated with minerals was found to be rich in carboxyl C and alkyl C, as revealed by synchrotron based C 1s X-ray absorption near edge structure (NEXAFS, conducted in Australia Synchrotron) and the Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra. Overall, the study revealed the role of AM fungi in advancing the formation of microaggregates and increasing the sequestration of organic C and N in macroaggregates in the eco-engineered Fe ore tailings. These suggest that AM fungi inoculum be added to pioneer plants to not only enhance plant growth via improved nutrient and water acquisition, but also to advance aggregate formation and quality via increased organic C and N sequestration with impacted mineral particles.</p>

Long-term variations in individual particle types in the aerosol of Phoenix, Arizona, as determined using automated electron microprobe analysis and multivariate statistical techniques

1993 ◽  
Vol 51 ◽  
pp. 742-743
Author(s):  
Karen A. Katrinak ◽  
James R. Anderson ◽  
Peter R. Buseck
Keyword(s):  
Electron Microprobe ◽  
Fine Fraction ◽  
Coarse Fraction ◽  
Motor Vehicles ◽  
Multivariate Statistical Methods ◽  
Multivariate Statistical ◽  
X Ray ◽  
Mineral Particles ◽  
Anthropogenic Air Pollutants

Aerosol samples were collected in Phoenix, Arizona on eleven dates between July 1989 and April 1990. Elemental compositions were determined for approximately 1000 particles per sample using an electron microprobe with an energy-dispersive x-ray spectrometer. Fine-fraction samples (particle cut size of 1 to 2 μm) were analyzed for each date; coarse-fraction samples were also analyzed for four of the dates.The data were reduced using multivariate statistical methods. Cluster analysis was first used to define 35 particle types. 81% of all fine-fraction particles and 84% of the coarse-fraction particles were assigned to these types, which include mineral, metal-rich, sulfur-rich, and salt categories. "Zero-count" particles, consisting entirely of elements lighter than Na, constitute an additional category and dominate the fine fraction, reflecting the importance of anthropogenic air pollutants such as those emitted by motor vehicles. Si- and Ca-rich mineral particles dominate the coarse fraction and are also numerous in the fine fraction.

X-ray microscopy by phase-retrieval methods at the advanced light source

2003 ◽  
Vol 104 ◽  
pp. 557-561 ◽  
Author(s):  
M. R. Howells ◽  
H. Chapman ◽  
S. Hau-Riege ◽  
H. He ◽  
S. Marchesini ◽  
...  
Keyword(s):  
Light Source ◽  
Phase Retrieval ◽  
X Ray ◽  
Advanced Light Source

Occurrence of Vesicular-Arbuscular Mycorrhizal Fungi in Alberta, Canada

1993 ◽  
Vol 48 (11-12) ◽  
pp. 923-929 ◽  
Author(s):  
S. M. Boyetchko ◽  
J. P. Tewari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Fungal Species ◽  
Glomus Aggregatum ◽  
X Ray ◽  
Vesicular Arbuscular ◽  
Spore Walls ◽  
Scanning Electron

Abstract Three V A mycorrhizal fungal species were isolated from soils in Alberta, Canada and examined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Mature spores of Glomus aggregatum developed an outer hyaline wall which contained lower levels of calcium than the middle wall. Examination of G. pansihalos spores revealed a lower level of calcium in the outer evanescent wall as compared to the ornamented wall. When spores of Entrophospora infrequens were examined, the wall of the vesicle was found to contain similar levels of calcium as the ornamented wall of the spore. The significance of the results concerning the presence of calcium in mycorrhizal spore walls is discussed, as is the occurrence of the mycorrhizal species.

scholarly journals Soft x-ray seeding studies for the SLAC Linac Coherent Light Source II

2019 ◽  
Vol 22 (11) ◽  
Author(s):  
E. Hemsing ◽  
G. Marcus ◽  
W. M. Fawley ◽  
R. W. Schoenlein ◽  
R. Coffee ◽  
...  
Keyword(s):  
Light Source ◽  
Coherent Light ◽  
X Ray ◽  
Linac Coherent Light Source ◽  
Coherent Light Source

scholarly journals New ambient pressure X-ray photoelectron spectroscopy endstation at Taiwan light source

2019 ◽  
Author(s):  
Chia-Hsin Wang ◽  
Sun-Tang Chang ◽  
Sheng-Yuan Chen ◽  
Yaw-Wen Yang
Keyword(s):  
Light Source ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
X Ray

Development of a hard x-ray split-delay system at the Linac Coherent Light Source

2017 ◽  
Author(s):  
Diling Zhu ◽  
Yanwen Sun ◽  
Donald W. Schafer ◽  
Hongliang Shi ◽  
Justin H. James ◽  
...  
Keyword(s):  
Light Source ◽  
Delay System ◽  
Coherent Light ◽  
X Ray ◽  
Linac Coherent Light Source ◽  
Coherent Light Source

Research on Nozzle Geometry Measurement with Synchrotron Radiation X-Ray Phase Contrast Imaging Technique

2013 ◽  
Vol 779-780 ◽  
pp. 1007-1014
Author(s):  
Cang Su Xu ◽  
Qi Yuan Luo ◽  
Jian Ma ◽  
Fang Qi ◽  
Yi Fan Xu
Keyword(s):  
Internal Structure ◽  
Light Source ◽  
Flow Dynamics ◽  
Nozzle Geometry ◽  
Contrast Imaging ◽  
X Ray ◽  
Performance And Emission ◽  
Injector Nozzle ◽  
Fuel Atomization ◽  
Geometry Measurement

The performance and emission characteristics of diesel engines are largely governed by fuel atomization and spray processes which in turn are strongly influenced by the flow dynamics inside the injector nozzle. Accurate measurement of the nozzle geometry is important for the study of the flow dynamics. Using the third-generation synchrontron radiation light source of the ShangHai Light Source (SSRF), the research team successfully captured the internal structure images of the single hole nozzle and multi-hole nozzle. According to the captured images, the researchers clearly observed the internal structure of nozzle as well as the sac region. The diameter and length of the nozzles and orifice angle were also be accurately measured.

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