Release Of Inorganic Phosphorus Research Articles

Exploring novel potential of mycosynthesized magnetic nanoparticles for phosphatase immobilization and biological activity

Among different microbes, fungi are proficient candidates for the extracellular synthesis of iron nanoparticles. For biogenic synthesis of iron nanoparticles, a thermophilic mould Myceliophthora thermophila BJTLRMDU7 was used in this study. Mycogenic magnetic nanoparticles were used for phosphatase immobilization and therapeutic applications such as antimicrobial and antimalarial activity. Firstly, the phosphatase was immobilized on biogenic iron nanoparticles with an efficiency of >56 %. Immobilized enzyme was optimally active at 60 °C and pH 5. Immobilized phosphatase was recycled using external magnetic field up to 4th cycle retaining >50 % activity. The immobilized phosphatase efficiently released inorganic phosphate from different flours such as wheat, maize and gram at 37 °C and 60 °C. There was continuous increase in the release of inorganic phosphorus from all samples with incubation time at 37 °C and slight reduction at 60 °C. These nanoparticles showed the effective antimicrobial activity against Bacillus subtilis, Escherichia coli and Myceliophthora thermophila. Further, the synthesized iron nanoparticles showed antimalarial potential against Plasmodium falciparum. Biogenic nanoparticles did not exhibit hemolytic activity and cytotoxicity. Therefore, biogenic iron nanoparticles could be used as a suitable matrix for immobilization of enzymes and safe therapeutics.

Phosphorus distribution in the water and sediments of the Ganga and Yamuna Rivers, Uttar Pradesh, India: insights into pollution sources, bioavailability, and eutrophication implications.

River nutrient enrichment is a significant issue, and researchers worldwide are concerned about phosphorus. The physicochemical characteristics and phosphorus (P) fractions of 36 sediment and water samples from the Ganga (Kanpur, Prayagraj, Varanasi) and Yamuna (Mathura, Agra, Prayagraj) rivers were examined. Among the physicochemical parameters, pH exceeded the permissible limit in Ganga and Yamuna River water and sediment samples. Electrical conductivity (EC) and alkalinity were within the permissible limits, whereas total nitrogen (TN) exceeded the limit in Yamuna water. The analysis of phosphorus fractions indicated the dominance of inorganic phosphorus (IP) (76% in Ganga and 96% in Yamuna) over organic phosphorus in both rivers, suggesting the mineralization and microbial degradation as major processes responsible for transforming OP to IP. The positive correlation of pH with IP, AP (apatite phosphorus), and NAIP (non-apatite inorganic phosphorus) explains the release of inorganic phosphorus under alkaline conditions. The correlation between total organic carbon (TOC), TN, and organic phosphorus (OP) indicated the organic load in the rivers from allochthonous and autochthonous sources. Phosphorus released from river sediments and the concentration of phosphate in overlying river water show a positive correlation, suggesting that river sediments may serve as phosphorus reservoirs. The average phosphorus pollution index (PPI) was above one in both rivers, with relatively higher PPI values observed in the Yamuna River, indicating the contamination of sediment with phosphorus, indicating the contamination of sediment with phosphorus. This study revealed variations in the P fractionation of the sediment in both rivers, primarily as a result of contributions from different P sources. This information will be useful for applying different mitigation techniques to lower the phosphorus load in both river systems.

Fraction analysis of soil phosphorus and dissolved organic matter reveals the release potential of phosphorus and its influencing factors in the submerged area of the Sanhekou Reservoir, China

Abstract Different forms of inorganic phosphorus in surface soils can be released into water or adsorbed into sediment in response to various environmental factors. Although the Sanhekou Reservoir is still under construction, the periodic wetting-drying events may result in the release of inorganic phosphorus from the soil into the water once it is completed. Therefore, this study aimed to investigate the background soil values and estimate the phosphorus release fluxes of the Puhe River, Wenshuihe River, and Jiaoxihe River of the reservoir. We would like to provide a theoretical basis for the subsequent management and ecological protection of the reservoir based on this study. The Chang–Jackson chemical continuous extraction method was used to determine the forms of inorganic phosphorus in the soil, and fluorescence data were obtained by excitation–emission matrix combined with parallel factor (EEM-PARAFAC). The results showed that there were four types of phosphorus in the soil of the reservoir, including calcium-bound phosphate, aluminium-bound phosphate, iron-bound phosphate, and occluded phosphate. The total quantities of these phosphorus types were measured to be 6.71 × 104, 1.14 × 104, 0.91 × 104, and 0.49 × 104t, respectively. Additionally, it was observed that there was 2.12 × 104 t of bioavailable phosphorus present in the soil.

Biogeochemical buffers in a eutrophic coastal lagoon along an oxic-hypoxic transition

The effects of bottom water oxic-hypoxic transition on estuarine benthic ecosystems have been extensively studied as oxygen (O2) depletion leads to the accumulation of toxic sulphides impacting sediment biogeochemical functioning. The role of benthic macrofauna in modulating such effects is understudied. Macrofauna may increase the resilience of sediments to critical O2 transitions via direct and indirect mechanisms acting upon organic matter (OM) and solid-phase metal pools that represent internal geochemical buffers for sediments. In this study we analysed whether and how the macrofaunal community may facilitate sediment resilience against short-term hypoxic events. Thus, net fluxes of reduced metals and inorganic nutrients were measured under oxic conditions and induced hypoxia in intact cores representing most of the sedimentary environments of the eutrophic Curonian Lagoon. Afterwards, distance-based linear models (distLM) were applied to explore the relationship between the dominant macrofauna taxa, sediment properties and the net fluxes. The results show a mosaic of sedimentary environments including OM poor (0.3%) sandy areas, OM rich (23%) muddy areas and variable combinations of these extremes. The variability of the macrofauna community was comparatively much lower, with oligochaetes and chironomids representing the most abundant taxa at most sampling sites. Along with the induced oxic-hypoxic transition metal fluxes tended to increase, together with dissolved inorganic phosphorus release, whereas dissolved inorganic nitrogen and silica tended to decrease. The distLM model evidenced that sediment properties accounted for 84.2% of the total flux variability whereas Chironomidae, Gammaridae and Gastropoda cumulatively accounted for 15.8% of the total explained variation in fluxes under oxic conditions. Under hypoxic conditions macrofauna explained a measurable but minor fraction of flux variability whereas OM and granulometry were best predictors. In the Curonian Lagoon macrofauna has a minor role in regulating fluxes and in providing biogeochemical services as compared to sediment features. As such, the benthic system appears vulnerable to short-term events of O2 shortage.

Aspergillus niger Enhances Organic and Inorganic Phosphorus Release from Wheat Straw by Secretion of Degrading Enzymes and Oxalic Acid.

To explore the mechanisms of crop straw degradation and phosphorus (P) release by phosphate-solubilizing fungi (PSF), a typical PSF Aspergillus niger (A. niger, ANG) was investigated for the degradation of wheat straw (WST) in this work. The results revealed that A. niger significantly increased wheat straw degradation (30%) compared with no A. niger treatment (7.7%). Meanwhile, more than 92% of total P was released from WST by A. niger, much higher than from WST treatment (69.5%). Although the ratios of inorganic P release between WST and WST + ANG treatments were similar (17.6 vs 19.7%), a significant difference occurred between their release of organic P, i.e., WST (51.9%) vs WST + ANG (72.5%). The high enzyme activity of β-1,4-glucanase and β-glucosidase produced by A. niger contributed to the wheat straw degradation and organic P release compared with no A. niger treatment. Oxalic acid secreted by A. niger dominated the release of inorganic P from WST. Our findings suggested that A. niger is an efficient microbial agent for crop straw degradation and P release, which could be a candidate in the pathway of straw return.

Kinetic Release Characteristics of Organic Phosphorus of Sediment-water and Water Quality Risks

To reveal the characteristics of organic phosphorus release from lake sediments and its potential impact on water quality, six lake sediments from Yunnan Plateau and the middle and lower reaches of the Yangtze River in China were selected. We studied the differences in the kinetics of dissolved organic phosphorus (DOP) and dissolved inorganic phosphorus (SRP) release from sediments. The effects of organic phosphorus morphology and dissolved organic matter (DOM) characteristics on sediment phosphorus release were investigated, and the water quality risks of sediment DOP release were discussed. The results showed that:① the release kinetics of sediment DOP and SRP were similar; both followed the second-order kinetic model, starting with a rapid release phase, followed by a slow release, and the release curve gradually leveled off and reached the maximum release. ② The release of organic phosphorus was related to organophosphorus morphology and organic matter. Active organic phosphorus (LOP) and medium active organic phosphorus (MLOP) were the DOP forms mainly released into the overlying water during the rapid release phase. The proportion of LOP and MLOP to total organic phosphorus (DTP) decreased in the late release stage, whereas the proportion of non-active organic phosphorus (NLOP) increased; further, the degree of humification and aromaticity of organic matter gradually increased with phosphorus release, and its activity decreased, resulting in a slower release rate at the later stage. ③ Compared with that of SRP, the risk of DOP release was higher, accounting for 47%-77% of the total amount of DTP. It was also found that the higher the nutrient level of the lake, the greater the release of DOP and the higher the water quality risk. Therefore, not only the release of inorganic phosphorus but also that of organic phosphorus should be of concern in the process of phosphorus release from lake sediments to prevent the underestimation of phosphorus release and water quality risk.

A new method for detecting Na+ , K+ -ATPase activity by ICP-MS: Quantitative analysis on the inhibitory effect of rhein on Na+ , K+ -ATPase activity by ICP-MS in HCT116 cells.

Rhein is an active component from Chinese herbal medicine. It can cause diarrhea by inhibiting Na+ , K+ -ATPase activity on intestinal epithelial cells, thus decreasing the re-absorption of Na+ from intestinal tract to blood. However, when this Na+ , K+ -ATPase inhibition was quantitated by a colorimetric method that measures ATPase-catalyzed release of inorganic phosphorus, the data obtained were inconsistent and showed great variation. We developed a novel method using inductively coupled plasma mass spectrometry (ICP-MS) to quantitate the amount of intracellular Rb+ . This method largely mimics the 86 RbCl tracer flux assay, but it uses non-radioactive RbCl as a flux substrate. The results demonstrated that this method has better precision and accuracy than the conventional colorimetric method. More importantly, this method is free from radioactive substances, which is expected to make it safer and more convenient than the radioactive 86 RbCl tracer flux method. In conclusion, the ICP-MS method for Na+ , K+ -ATPase activity determination is novel and accurate. It can also provide a reference for studying the transport of other metal ions across membranes under biological conditions.

Organic acid regulation of inorganic phosphorus release from Mollisols with different organic matter contents

AbstractPhosphorus (P) is used to enhance agricultural productivity. Organic acids increase the release of inorganic phosphorus (Pi) into soil solutions and thereby improve phosphorus utilization in soils; however, the effects of both organic acids and the soil organic matter contents on Pi release are poorly understood. To assess the importance of these factors in determining phosphorus availability, the release of soil Pi fractions (i.e. aluminium‐bound phosphorus (Al‐P), iron‐bound phosphorus (Fe‐P), occluded phosphorus (O‐P) and calcium‐bound phosphorus (Ca‐P)) was evaluated on addition of organic acids (citric, oxalic and malic acids) to soils from Mollisols region that had different organic matter contents and received phosphorus fertilizer. Biochemically produced humic acid was used to modify soil organic matter contents. Among Pi fractions, the Fe‐P fraction had the highest concentration in all the soils with different organic matter contents. In the presence of organic acids, the release of Pi fractions decreased as the soil organic matter increased. Among the fractions, Al‐P had the highest release, followed by Fe‐P. Comparison among various organic acids revealed that oxalic acid was the most effective for Pi release. Path analysis showed that Al‐P release had larger direct‐path and indirect‐path coefficients, which implied that Al‐P release had the largest contribution to total Pi (TPi) release. We concluded that the effectiveness of organic acids in improving soil phosphorus availability was most pronounced in soils with low organic matter contents, but further field‐scale research is needed to confirm this. Al‐P was the most effective source of inorganic phosphorus in Mollisols.

Dark accelerates dissolved inorganic phosphorus release of high-density cyanobacteria.

Bloom-forming cyanobacteria dramatically influence nutrient cycling in eutrophic freshwater lakes. The phosphorus (P) assimilation and release of bloom-forming cyanobacteria significantly may also affect the phosphorus source and amounts in water. To understand the phosphorus release process of bloom-forming cyanobacteria below the accumulated surface and sedimentary bloom-forming cyanobacteria, the degradation of bloom-forming cyanobacteria dominated by Microcystis spp. at different cell density in the dark was investigated over a 25-day microcosm experiment. The dissolved inorganic phosphorus (DIP) and dissolved total phosphorus (DTP) contents increased with the increment of cyanobacterial density, and the dark status markedly increased the proportion of DIP in water during the decline period of bloom-forming cyanobacteria. Meanwhile, the process of cyanobacterial apoptosis accompanied by the changes of malondialdehyde (MDA) and phosphatase (AKP) contents, and the increases of superoxide dismutase (SOD) and catalase (CAT) activities of cyanobacteria in the dark, especially in low-density groups (5.23×108 cells L-1), which further affect the physicochemical water parameters. Moreover, the DIP release from high-density cyanobacteria (7.86×107 cells L-1~5.23×108 cells L-1) resulted from the relative abundance of organophosphorus degrading bacteria in the dark. Therefore, the fast decay of cyanobacteria in the dark could accelerate DIP release, the high DIP release amount from accumulated bloom-cyanobacteria provide adequate P quickly for the sustained growth of cyanobacteria.

Organic acids promote phosphorus release from Mollisols with different organic matter contents

Organic acids could improve the phosphorus (P) availability through enhancing the release of inorganic phosphorus (P<sub>i</sub>) in the soil. However, the effects of organic acids on the P<sub>i</sub> release are still poorly understood, especially from soils with different organic matter contents. Here, a biochemically produced humic acid and P fertiliser were added to the soil to modify the content of the soil organic matter (SOM) and soil P, respectively. And then the soil samples were incubated at 25 °C for 30 days. The release of P<sub>i</sub> fractions (such as H<sub>2</sub>O-P<sub>i</sub>, NaHCO<sub>3</sub>-P<sub>i</sub>, NaOH-P<sub>i</sub>, HCl-P<sub>i</sub>, and Residual-P) from the soils with different organic matter contents in the presence of citric, oxalic, and malic acids was evaluated using a sequential chemical fractionation method. The results showed that the release of the NaHCO<sub>3</sub>-P<sub>i</sub>, NaOH-P<sub>i</sub>, and HCl-P<sub>i</sub> fractions also showed a decreasing trend with an increasing content of soil organic matter, and more NaOH-P<sub>i</sub> than the other P<sub>i</sub> fractions was generally released in the presence of organic acids. Considering the types of organic acids, oxalic acid and malic acid most effectively and least effectively released P<sub>i</sub>, respectively. The path analysis indicated that the NaOH-P<sub>i</sub> release had the highest direct and indirect effects on the total inorganic P (TP<sub>i</sub>) release. NaOH-P<sub>i</sub> was, therefore, the most effective source of P<sub>i</sub> in the Mollisols.

Roles of bacterial biomass, physiology and community in sediment phosphorus solubilizing at varying hydrostatic pressures

In this study, the mechanism behind the effect of hydrostatic pressure on phosphorus solubilization from sediment to water was studied in culture experiments using reactors pressurized at 0.1, 0.2, 0.5, and 1.0 MPa. In the sterilized group, the phosphorus content in the sediment was not affected by the hydrostatic pressure. In the unsterilized group, the phosphorus release values were 162, 198, 253, and 289 mg kg−1 at 0.1, 0.2, 0.5, and 1.0 MPa, respectively. In addition, when the hydrostatic pressure was increased from 0.1 to 1 MPa, the activity of alkaline phosphatase increased from 210 to 357 mg kg−1 h−1. The abundance of inorganic phosphorus-solubilizing bacteria increased with rising hydrostatic pressure, but the abundance of organic phosphorus-solubilizing bacteria was highest when the hydrostatic pressure was 0.5 MPa. Pearson regression analysis indicated that the maximum organic phosphorus-solubilizing capacity was positively correlated with the alkaline phosphatase activity (R = 0.97, p < 0.05), but not to the biomass of the organic phosphorus-solubilizing bacteria. Conversely, the maximum inorganic phosphorus-solubilizing capacity was positively correlated to the biomass of the inorganic phosphorus-solubilizing bacteria (R = 0.974, p < 0.05), but not to the alkaline phosphatase activity. The makeup of the bacterial community varied as the hydrostatic pressure increased, but the major bacterial phyla did not change. This implies that changes in the bacterial community did not contribute to variations in phosphorus release. Our results suggest that bacteria are the main factor influencing phosphorus release at various hydrostatic pressures. For organic phosphorus release, the physiology of the organic phosphorus-solubilizing bacteria was more important than biomass, while for inorganic phosphorus release, the biomass of the inorganic phosphorus-solubilizing bacteria was more important than cell physiology.

A novel fungal beta-propeller phytase from nematophagous Arthrobotrys oligospora: characterization and potential application in phosphorus and mineral release for feed processing

Phytases are widely utilized in feed industry to increase the utilization of phosphorus, minerals, and amino acids for improvement of animal and human nutrition. At present, all known β-propeller phytases (BPP) have been generated from bacteria, particularly Bacillus. In this work we report for the first time a new fungal-derived BPP phytase. We identified a phytase highly differentially expressed only in the parasitic stage of a nematophagous fungus, Arhtrobotrys oliogospora, during the development of the 3D traps. We found that this phytase was homologous to the known bacterial BPP phytase, thus we referred the new phytase to Aophytase. The heterologous expression of codon-optimized Aophytase gene in Pichia pastoris was successfully investigated to yield recombinant Aophytase (r-Aophytase) with high specific enzyme activity of 74.71 U/mg, much higher than those of recombinant BPP phytases derived bacteria. The kinetic parameters of the r-Aophytase, the optimum pH and temperature, as well as the effects of surfactant, EDTA and different ions on its enzyme activity were further investigated. The potential utilization of r-Aophytase in feed processing was finally explored. We found that the optimal pH value was about 7.5, and the optimal temperature was 50 °C.; r-Aophytase significantly increased the release of inorganic phosphorus from soybean meal, and improved the release of soluble minerals from the durum wheat flour and finger millet flour. The findings indicate its potential utilization in the feed processing to ameliorate nutritional value of cereals and animal feed in the future.

Different pathways of nitrogen and phosphorus regeneration mediated by extracellular enzymes in temperate lakes under various trophic state.

Several Italian and Chinese temperate lakes with soluble reactive phosphorus concentrations < 0.015mgL-1 were studied to estimate nitrogen and phosphorus regeneration mediated by microbial decomposition and possible different mechanisms driven by prevailing oligo- or eutrophic conditions. Leucine aminopeptidase (LAP), beta-glucosidase (GLU) and alkaline phosphatase (AP), algal, and bacterial biomass were related to trophic and environmental variables. In the eutrophic lakes, high algal and particulate organic carbon concentrations stimulated bacterial respiration (> 20μgCL-1h-1) and could favor the release of inorganic phosphorus. High extracellular enzyme activities and phosphorus solubilizing bacteria abundance in sediments accelerated nutrient regeneration. In these conditions, the positive GLU-AP relationship suggested the coupling of carbon and phosphorus regeneration; an efficient phosphorus regeneration and high nitrogen levels (up to 0.067 and 0.059mgL-1 NH4 and NO3 in Italy; 0.631 and 1.496mgL-1 NH4 and NO3 in China) led to chlorophyll a peaks of 14.9 and 258.4μgL-1 in Italy and China, respectively, and a typical algal composition. Conversely, in the oligo-mesotrophic lakes, very low nitrogen levels (in Italy, 0.001 and 0.005mgL-1 NH4 and NO3, respectively, versus 0.053 and 0.371mgL-1 in China) induced high LAP, while low phosphorus (33.6 and 46.3μgL-1 total P in Italy and China, respectively) led to high AP. In these lakes, nitrogen and phosphorus regeneration were coupled, as shown by positive LAP-AP relationship; however, the nutrient demand could not be completely met without the supply from sediments, due to low enzymatic activity and phosphorus solubilizing bacteria found in this compartment.

Phosphorus mobility in dam reservoir affected by redox oscillations: An experimental study

The internal sedimentary phosphorus (P) load of aquatic systems is able to support eutrophication, especially in dam–reservoir systems where sedimentary P stock is high and where temporary anaerobic conditions occur. The aim of this study therefore is to examine the response of sedimentary P exposed to redox oscillations. Surface sediments collected in the Champsanglard dam–reservoir (on the Creuse River, France) were subjected to two aerobic phases (10 and 12 days) alternated with two anaerobic periods (21 and 27 days) through batch incubations. The studied sediment contained 77 ± 3 μmol/g DW of P, mainly associated with the ascorbate fraction (amorphous Fe/Mn oxyhydroxides). The used sediment was rich in organic matter (OM) (21% ± 1%) with primarily allochthone signature. Our results showed that redox oscillations enhance dissolved inorganic phosphorus release at sediment/water interface. During the first anaerobic stage, the P release was mainly controlled by the dissolution/precipitation of iron minerals. The more pronounced increase of P release during the second anaerobic stage (44%) was due to various mechanisms related to the change in quality of dissolved organic matter (DOM), namely a higher SUVA254 and humification indices. The release of more refractory DOM (rDOM) served to lower the microbial metabolism activity, possibly favored iron oxyhydroxide aggregation and thus limiting iron reduction. In addition, rDOM is able to compete for mineral P sorption sites, leading to a greater P release. In reservoir with predominant allochthone OM input, the release of more aromatic DOM therefore plays an important role in P mobility.

Different mechanisms of organic and inorganic phosphorus release from Mollisols induced by low molecular weight organic acids

Enhancement of inorganic phosphorus (Pi) release by low molecular weight organic acids (LMWOA) increases soil phosphorus (P) availability to plant, but the release of organic phosphorus (Po) and the associated kinetics of both Pi and Po release by LMWOA have not been well considered. The aim of this study was therefore to investigate the impacts of three common LMWOA (citric acid, oxalic acid, and malic acid) on the kinetic release of Pi and Po in a black clay soil in northeast China. All kinetic data were well described by the Elovich and power functions models (P citric acid (2.67 mg kg−1) > malic acid (1.76 mg kg−1). In contrast, Pi release by LMWOA resulted from mobilization of the moderately labile NaOH-Pi (Fe/Al-P) and HCl-Pi (Ca-Pi) fractions in the order of citric a...

Concentration of Phosphorus in Sediments Interstitial Water as Affected by Distribution of Aquatic Plants in Dianchi Lake

In order to reveal the effect of aquatic plants distribution on the mass concentration of phosphorus in sediment interstitial water, the mass concentrations of Dissolved Total Phosphorus (DTP), Soluble Reactive Phosphorus (SRP) and Dissolved Organic Phosphorus (DOP) in the sediment interstitial water and overlying water from areas with or without plants in the same site of Dianchi were studied. The vertical variation characteristics of phosphorus forms in sediment interstitial water were analyzed to explore the effect of aquatic plants on the phosphorus forms in sediment interstitial water. The results showed: ①Aquatic plants had an significant effect on the phosphorus mass concentration of the sediment interstitial water in different Dianchi lakes. However, they varied with different distribution sites and depth. ②Aquatic plants significantly decreased the percentage of DOP contribution in the sediment interstitial water. The average contribution of DOP with aquatic plants was 32.87%, while that without plants reached 57.68%; ③Aquatic plants significantly inhibited the release of inorganic phosphorus in sediments and promoted the transformation of DOP. The SRP diffusion flux at sediment-water interface with aquatic plants was increased by 39.99% as compared with that without plants; ④The growth of aquatic plants significantly reduced the concentration of phosphorus in sediment interstitial water, especially DOP, and the reduction rate of the sediment interstitial water DOP was from 38.02% to 85.49%. Therefore, the analysis of the contribution and reduction rate of aquatic plants on the sediment interstitial water DOP was of great importance in understanding the relationship between aquatic plants and DOP, as well as the mineralization of organic phosphorus in sediments.

Phytase-producing Bacillus sp. inoculation increases phosphorus availability in cattle manure

Organic wastes rich in phosphorus (P) are considered an alternative to decrease the dependence on chemical P fertilization in crops and pastures. Microbial inoculants are being studied as a tool to increase plant P availability in organic wastes. In this study, we explore the effect of inoculation with Bacillus sp. MQH-19 (a native phytase-producing bacterium) on the release of inorganic phosphorus (Pi) in cattle manure with low available P but a high total P content. Bacteria inoculation resulted in a higher release of Pi (8% in NaHCU3 and 13% in NaOH-EDTA extracts) compared with that of uninoculated manure (0.7% in NaHCU3 and 0.1% in NaOH-EDTA extracts). However, a greater amount of Pi was released in inoculated manure supplemented with phytate (47% in NaHCU3 and 117% in NaOH-EDTA extracts) compared with that of uninoculated manure supplemented with phytate (30% in NaHCU3 and 15% in NaOH-EDTA extracts). In addition, the use of denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) revealed that the bacterial community structure in manure was affected by inoculation and that the prevalence of Bacillus sp. MQH-19 decreased during incubation (6 days). This study demonstrates that Pi availability in cattle manure can be increased by phytase-producing bacteria inoculation. Phytase-producing bacteria inoculation might represent an attractive strategy to increase P availability in agricultural wastes, which are used as organic fertilizers in crops and pastures.

Effect of a mixed substrate on phytase production by Rhizopus oligosporus MTCC 556 using solid state fermentation and determination of dephytinization activities in food grains

Mustard oilcake was used as a novel substrate for phytase production with Rhizopus oligosporus MTCC 556. A mixed substrate (wheat bran:mustard oil cake) was used to optimize different medium components under solid state fermentation at a 62% moisture content, pH 5.5, 30°C, an inoculum level of 15%, and a ratio of the volume of a salt solution to the mass of mixed substrate 1.5 mL:10 g. Different carbon and nitrogen sources were used for production of phytase. Use of the nutritional supplements maltose and ammonium sulfate resulted in high phytase yields. The hydrolytic ability of partially purified phytase was evaluated using 5 different food grains. Wheat flour showed a 43.78% phytic acid reduction, rice flour showed 92% release of inorganic phosphorus, and corn flour showed 81 and 68% releases of soluble proteins and reducing sugars. Thus, phytase is suitable for feed applications.

Sediment–water exchange of nutrients in the Marsdiep basin, western Wadden Sea: Phosphorus limitation induced by a controlled release?

To quantify the release of inorganic phosphorus from the sediments and assess its contribution to present primary production, a basin-wide study of the Marsdiep (western Wadden Sea, The Netherlands) was performed. Two distinct sedimentary zones were identified: a depositional area characterized by a high content of silt and organic carbon and a small grain size and the majority of the area, composed of fine/medium sand and a low organic carbon content. The sediment–water exchange was higher in the fine grained depositional area and based on a relationship found between the release of inorganic phosphorus and the silt content, a total annual release of 1.0×107mol P was estimated for the whole Marsdiep basin. A spatial variability in the processes controlling the nutrient release was found. The exchange in the depositional area resulted mainly from molecular diffusive transport, with mineralization and sorption determining the concentration of inorganic phosphorus in the porewater. For the coarser sediment stations the activity of macrofauna clearly enhanced the fluxes. Given the relative demand of nutrients (N:P:Si) for phytoplankton growth, the release was phosphorus deficient during most of the year. Nevertheless, it increased from February until September, in parallel with the increase in temperature and light, thus having the potential to fuel primary production during their seasonal growth period. In terms of absolute values, our results show that the present exchange, enhanced by the activity of macrofauna has the potential to fuel a significant fraction of the recent levels of primary productivity.

Phosphorus fractions and cycling in the sediment of a shallow eutrophic pond

The aim of this study was to quantitatively determine the phosphorus fractional composition of the eutrophicated West Pond sediment using vertical and seasonal changes (positive-upwards and/or negative-downwards) in the phosphorus cycling across the sediment-water, and to examine the most effective potential fraction or fractions on phosphorus release and the pond’s eutrophication process. In this study, mean release values of phosphorus in depths and months representing the seasons (April, July, October, January) varied between 9.19 (January, 0-5 cm) and 119.08 μg m-2 d-1 (October, 0-5 cm) in West Pond sediment which supplies water to the Sakaryabasi Fish Culture and Research Station. The mean negative phosphorus release dependent on months and depths were estimated as 1.25 μg m-2 d-1 (July, 5-10 cm) and 46.45 μg m-2 d-1 (October, 10-15 cm). The distribution of phosphorus fractions in the pond sediment: total organically bound phosphorus fraction (Org≈P) > calcium bound phosphorus fraction (Ca≈P)> carbonate bound phosphorus fraction (CO3≈P) > iron + aluminum bound phosphorus fraction (Fe+Al≈P). In line with research findings the negative phosphorus release dependent on months and depths have revealed quantitatively that West Pond sediment is a sink not a source in terms of phosphorus. In the light of this, conservation of the aquatic macrophytes, role in preventing/suppressing the dissolved inorganic phosphorus release from sediment to overlying water, suggested as the best management technique of West Pond.