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{"Abstract":["Interactions between plants and soil microbes influence plant\n nutrient transformations, including nitrogen (N) fixation, nutrient\n mineralization, and resource exchanges through fungal networks.\n Physical disturbances to soils can disrupt soil microbes and\n associated processes that support plant and microbial productivity.\n In low resource drylands, biological soil crusts\n ("biocrusts") occupy surface soils and house key\n autotrophic and diazotrophic bacteria, non-vascular plants, or\n lichens. Interactions among biocrusts, plants, and fungal networks\n between them are hypothesized to drive carbon and nutrient dynamics;\n however, comparisons across ecosystems are needed to generalize how\n soil disturbances alter microbial communities and their\n contributions to N pools and transformations. To evaluate linkages\n among plants, fungi, and biocrusts, we disturbed all unvegetated\n surfaces with human foot trampling twice yearly in dry conditions\n from 2013-2018 in cyanobacteria-dominated biocrusts in Chihuahuan\n Desert grassland and shrubland ecosystems. Our study included\n microbial communities and N pools sampled at different time points\n in the disturbance treatments at one or both sites. We began our\n sampling after observations in April 2018 that the chlorophyll a\n content was at least double in control than disturbed plots in both\n ecosystems (Chung et al. 2019). Stomping occurred in May, and we\n collected soil and plant samples in June 2018 for N pools and soil\n and root fungal abundance. We collected additional soil samples in\n September 2018 and conducted the 15N tracer experiment to observe\n rates of N transfer from biocrust to plants before the fall stomp\n treatment in October. We collected chlorophyll a samples and soils\n for sequencing bacteria in September of 2019, also before the fall\n stomp treatment."]}
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Phototrophs, electricity, and the circular economy
Purple photosynthetic bacteria are emerging as both valuable biotechnological tools and important players in various ecosystems. This extended abstract highlights recent research from the Bose lab at Washington University in St. Louis touching on both of these ideas. Specifically, it discusses the use of "electrotrophic" bacteria as biocatalysts for microbial electrosynthesis, and the prevalence of these microbes in ecosystems like marine wetlands.
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- PAR ID:
- 10506610
- Publisher / Repository:
- Zenodo
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Sinking or sedimentation of biological aggregates plays a critical role in carbon sequestration in the ocean and in vertical material fluxes in waste-water treatment plants. In both these contexts, the sinking aggregates are “active,” since they are biological hot-spots and are densely colonized by microorganisms including bacteria and sessile protists, some of which generate feeding currents. However, the effect of these feeding currents on the sinking rates, trajectories, and mass transfer to these "active sinking particles," has not previously been studied. Here we use a novel scale-free vertical-tracking microscope (a.k.a. Gravity Machine, Krishnamurthy et al. "Scale-free vertical tracking microscopy." Nature Methods (2020)) to follow model sinking aggregates (agar spheres) with attached protists (Vorticella convallaria), sinking over long distances while simultaneously measuring local flows. We find that activity due to attached \vortc causes significant changes to the flow around aggregates in a dynamic manner and reshapes mass transport boundary layers. Furthermore, we find that activity-mediated local flows along with sinking modify the encounter and plume cross-sections of the aggregate and induce sustained aggregate rotations. Overall our work shows the important role of biological activity in shaping the near-field flows around aggregates with potentially important effects on aggregate fate and material fluxes.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.5281/zenodo.10079953
