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Organic Phosphorus (organic + phosphorus)
Selected AbstractsWidespread known and novel phosphonate utilization pathways in marine bacteria revealed by functional screening and metagenomic analysesENVIRONMENTAL MICROBIOLOGY, Issue 1 2010Asuncion Martinez Summary Phosphonates (Pn), compounds with a direct C,P bond instead of the more common C,O,P ester bond, constitute a significant fraction of marine dissolved organic phosphorus and recent evidence suggests that they may be an alternative source of P for marine microorganisms. To further characterize the microorganisms and pathways involved in Pn utilization, we screened bacterioplankton genomic libraries for their ability to complement an Escherichia coli strain unable to use Pns as a P source. Using this approach we identified a phosphonatase pathway as well as a novel pair of genes that allowed utilization of 2-aminoethylphosphonate (2-AEPn) as the sole P source. These pathways are present in diverse bacteria common in marine plankton including representatives of Proteobacteria, Planctomycetes and Cyanobacteria. Analysis of metagenomic databases for Pn utilization genes revealed that they are widespread and abundant among marine bacteria, suggesting that Pn metabolism is likely to play an important role in P-depleted surface waters, as well as in the more P-rich deep-water column. [source] Rapid decomposition of phytate applied to a calcareous soil demonstrated by a solution 31P NMR studyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2010A. L. Doolette myo -Inositol hexakisphosphate (phytate) is widely regarded as an abundant form of soil organic phosphorus (P) in many soils. Its abundance is believed to be because of its resistance to microbial degradation. We examined the fate of phytate added to a calcareous soil as a solution at a concentration of 58 mg P kg,1, with and without the addition of wheat straw. The soil was incubated for 13 weeks, with phytate concentrations determined at 0, 1, 4, 7 and 13 weeks using NaOH-EDTA soil extraction followed by 31P nuclear magnetic resonance (NMR) spectroscopy. The phytate concentration declined rapidly, with 18% (phytate + wheat straw) and 12% (phytate) of the initial phytate remaining after 13 weeks. This coincided with an increase in the proportion of orthophosphate relative to total NaOH-EDTA extractable P (from 65 to 81%) and a small increase in , - and , -glycerophosphate concentration, providing evidence for the microbial degradation of phytate. The decrease in phytate concentration was consistent with a first-order decay with a half-life for phytate of 4,5 weeks. This study demonstrates that in the calcareous soil examined, phytate was not highly stable, but a potentially biologically available form of P. In order to quantify the concentration of P species, we developed an improved method of spectral deconvolution. This method accounted for a broad signal (3.5,6.5 ppm) in the monoester region of the spectra that represented up to 23% of the total extractable P. We found that when this broad signal was not included, phytate concentrations were over-estimated by up to 54%. [source] Dissolved organic phosphorus and sulphur as influenced by sorptive interactions with mineral subsoil horizonsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2001K. KaiserArticle first published online: 6 JAN 200 Summary This study tested the hypothesis that, like dissolved organic nitrogen (N), dissolved organic phosphorus (P) and sulphur (S) are more mobile in soil than is organic carbon (C). To do so, I compared the sorption of organic P and S to subsoil materials with that of organic C. Soil samples were equilibrated with water-soluble organic matter from the forest floor at pH 4 and in the equilibrium solutions organic C, P, and S, and their distributions between the hydrophilic and hydrophobic fraction were determined. Sorption of C within the organic matter did not differ from that of P and S. However, the hydrophilic fraction contained the vast majority of P and S and sorbed far less than the hydrophobic fraction. So the overall retention of organic P and S was smaller than that of organic C. This result suggested that dissolved organic matter is more important in the loss of plant nutrients than in the release of C from soil. [source] Efficiency of acid phosphatases secreted from the ectomycorrhizal fungus Hebeloma cylindrosporum to hydrolyse organic phosphorus in podzolsFEMS MICROBIOLOGY ECOLOGY, Issue 2 2010Julien Louche Abstract Ectomycorrhizal fungi may improve the phosphate nutrition of their host plants by secreting, into the soil solution, acid phosphatases (AcPases) able to release orthophosphate (Pi) from soil organic phosphorus (Po). Using cation-exchange chromatography, we separated four fractions with AcPase activity secreted by the ectomycorrhizal fungus Hebeloma cylindrosporum grown in a pure culture under P-starved conditions. Each AcPase active fraction displayed strong ability in vitro to hydrolyse a wide range of phosphate monoesters, but none of them efficiently hydrolysed phytate. Their efficiency to release Pi from soil NaHCO3 -extractable Po was studied in a sandy podzol used intact or autoclaved. Soils were collected in a 15-year-old Pinus pinaster stand, receiving regular fertilization or not. Autoclaving increased the NaHCO3 -extractable Po concentrations by 55% in unfertilized and by 32,43% in fertilized soils. The efficiency of each AcPase fraction was affected significantly by the soil fertilization regime and the soil treatment (intact vs. autoclaved). The proportion of labile Po enzyme ranged from 0% to 11% and 14% to 48% after 1 h of incubation in bicarbonate solutions extracted from intact and autoclaved soils, respectively. This work suggests that AcPases secreted from H. cylindrosporum could be efficient in recycling Po pools from soil microorganisms that may be delivered by soil autoclaving. [source] Integrated Modular Modeling of Water and Nutrients From Point and Nonpoint Sources in the Patuxent River Watershed,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2008Zhi-Jun Liu Abstract:, We present a simple modular landscape simulation model that is based on a watershed modeling framework in which different sets of processes occurring in a watershed can be simulated separately with different models. The model consists of three loosely coupled submodels: a rainfall-runoff model (TOPMODEL) for runoff generation in a subwatershed, a nutrient model for estimation of nutrients from nonpoint sources in a subwatershed, and a stream network model for integration of point and nonpoint sources in the routing process. The model performance was evaluated using monitoring data in the watershed of the Patuxent River, a tributary to the Chesapeake Bay in Maryland, from July 1997 through August 1999. Despite its simplicity, the landscape model predictions of streamflow, and sediment and nutrient loads were as good as or better than those of the Hydrological Simulation Program-Fortran model, one of the most widely used comprehensive watershed models. The landscape model was applied to predict discharges of water, sediment, silicate, organic carbon, nitrate, ammonium, organic nitrogen, total nitrogen, organic phosphorus, phosphate, and total phosphorus from the Patuxent watershed to its estuary. The predicted annual water discharge to the estuary was very close to the measured annual total in terms of percent errors for both years of the study period (,2%). The model predictions for loads of nutrients were also good (20-30%) or very good (<20%) with exceptions of sediment (40%), phosphate (36%), and organic carbon (53%) for Year 1. [source] Nutrient Uptake in a Large Urban River,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2007Catherine A. Gibson Abstract:, Small streams have been shown to be efficient in retaining nutrients and regulating downstream nutrient fluxes, but less is known about nutrient retention in larger rivers. We quantified nutrient uptake length and uptake velocity in a regulated urban river to determine the river's ability to retain nutrients associated with wastewater treatment plant (WWTP) effluent. We measured net uptake of soluble reactive phosphorus (SRP), dissolved organic phosphorus, ammonium (NH4), nitrate, and dissolved organic nitrogen in the Chattahoochee River, Atlanta, GA by following the downstream decline of nutrients and fluoride from WWTP effluent on 10 dates under low flow conditions. Uptake of all nutrients was sporadic. On many dates, there was no evidence of measurable nutrient uptake lengths within the reach; indeed, on several dates release of inorganic N and P within the sample reach led to increased nutrient export downstream. When uptake occurred, SRP uptake length was negatively correlated with total suspended solids and temperature. Uptake velocities of SRP and NH4 in the Chattahoochee River were lower than velocities in less-modified systems, but they were similar to those measured in other WWTP impacted systems. Lower uptake velocities indicate a diminished capacity for nutrient uptake. [source] | ||||||||||