Browsing by Subject "phosphate"

Now showing 1 - 4 of 4
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    Data for Extracellular Phosphate Modulation and Polyphosphate Accumulation by Corynebacterium matruchotii and Streptococcus mutans
    (2024-11-21) Ghose, Debarati; Jones, Robert S.; rsjones@umn.edu; Jones, Robert S; B-A-M (Biofilm-Apatite-Microbiome) Lab; School of Dentistry
    An alternative and understudied microbial mechanism that may influence demineralization is the microbially mediated ion exchange of Ca2+ and orthophosphate (Pi), which alters the saturation state of the mineral species within the surface enamel. There is a need to examine the ability of members of the oral microbiome to modulate Ca2+ and Pi, which control mineral solubility, in order to effectively evaluate mineralization therapies to improve oral health. Pi uptake was measured using an ascorbic acid assay during a BHI liquid culture growth of Corynebacterium matruchotii and Streptococcus mutans for up to 20 h. The initial and endpoint medium Ca2+ levels were measured using ICP-OES. Bacterial cells were examined at different growth stages using DAPI/polyP binding emission at 525 nm to detect the presence of internalized macromolecules of polyphosphates (polyP) that could drive Pi uptake. C. matruchotii (p = 0.0061) substantially accumulated Pi (3.84 mmol/L), with a concomitant formation of polyP. In contrast, S. mutans did not take up Pi or accumulate polyP. No significant Ca2+ drawdown in the media was observed in either strain. This study suggests that when examining the future efficacy of prevention technologies to improve, in vitro assays may consider including specific oral bacteria capable of substantial Pi uptake.
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    Genome editing in alfalfa (Medicago sativa) to hyper-accumulate phosphate
    (2019) Samac, Deborah A; Miller, Susan S; Dornbusch, Melinda R; Curtin, Shaun J
    Rock phosphate, the main source of phosphate (P) for crop fertilizers, is a finite resource that is predicted to be depleted in 50-100 years. P is a critical nutrient in agriculture and its application can dramatically improve plant productivity. However, many soils have excess amounts of P from application of animal manures and runoff of phosphate from agricultural lands is the major source of nonpoint water pollution in the Midwestern US. The goal of this project is to create mutations by gene editing in the ubiquitin E2 conjugating enzyme PHO2, involved in P signaling and P homeostasis in alfalfa so that plants hyper-accumulate phosphate. Such plants could be used to reduce soil P levels and reclaim P for use as a fertilizer. From a draft diploid Medicago sativa genome scaffold sequence and the alfalfa transcriptome database (AGED), three PHO2 genes were identified. The genes, two of which are >99% homologous (a/b), each have seven exons interspersed by six introns. The open reading frames are 912 amino acids except when an alternate splice site is used in a/b gene transcript resulting in a 902 amino acid sequence. Alfalfa plants grown under P limiting conditions expressed low levels of the a/b transcripts with higher levels seen for PHO2c, while application of higher P induced increased expression mainly of the a/b transcripts. Under high P conditions, roots and shoots accumulated 4.1x and 2.5x more P than in low P conditions, respectively. An initial CRISPR/Cas9/Cys4 reagent targeting all three genes was generated and used to transform alfalfa cv. RegenSY. A total of 67 verified transgenic plants were screened by acrylamide gel shift assays, cloning, and sequencing to identify plants with mutations. Mutations ranging from a 1 bp insertion to a 25 bp deletion were identified in a total of 10 plants and some plants had multiple targets hit. Recently, a second attempt at CRISPR/Cas9 mutation utilized a cassette vector system with either the tRNA or Cys4 splicing system and exonuclease components. Initial screening results indicate that the tRNA splicing system may have yielded greater numbers of mutations. TaqMan probes were designed to identify plants with changes in the target sites and were verified by restriction digestions, cloning, and sequencing. Data on inheritance of mutations and phosphate accumulation in edited plants will be presented. The results of these experiments demonstrate that editing of multiple targets can be accomplished in alfalfa, although the tetraploid inheritance of genes complicates analysis.
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    Iron Enhanced Sand Filters Performance and Maintenance Meta-Analysis
    (2025-04-15) Burrows, Levi J.; Gulliver, John S.; Erickson, Andrew J.; Weiss, Peter T.
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    Optimizing Biofiltration Media for the Capture of Phosphate and the Support of Vegetation Growth
    (2022-06) Kramarczuk, Kathryn
    AbstractBiofiltration is a stormwater management practice designed to treat runoff for harmful contaminants. A critical component of these systems is the granular media. In this study, I investigated six different types of base media (10% leaf compost, 20% leaf compost, 10% food compost, 20% food compost, sphagnum peat, reed sedge peat) and four different amendments (spent lime, biochar, iron and sphagnum peat) in various combinations with sand to test their capacity in mitigating phosphate release and supporting the growth of Switchgrass (Panicum virgatum) as an indicator of potential to support vegetation. The study consisted of an outdoor mesocosm experiment over three years, with 34 events total where 30 seeded mesocosms containing various media mixes received water from the Mississippi River (near downtown Minneapolis, MN, USA) that was spiked with phosphorus to simulate stormwater inputs. Soluble reactive phosphorus and nitrate concentration, pH, Switchgrass height over time, and Switchgrass biomass at senescence was measured each year. In general, mixes containing food compost, leaf compost, biochar with compost and spent lime with compost leached phosphorus whereas mixes containing peat, iron with compost, and sand adsorbed phosphorus. The mixes that leached phosphorus supported the most plant growth. Spent lime mixes and biochar mixes had the highest effluent nitrate concentrations indicating effects on N mineralization or nitrification. The iron and leaf compost layered media mix performed the best of all the mixes tested in terms of mitigating the release of phosphate and having the potential to support vegetation. Future research is necessary to determine if it can continue preventing phosphorus leaching and support vegetative growth with a higher percentage of compost and different plant species. Keywords: phosphate, nitrate, biofiltration, stormwater treatment, switchgrass (Panicum virgatum), compost, peat, biochar, water treatment residuals, iron