Low Phosphorus Content Research Articles

Safety and Efficacy of Burosumab in Pediatric Patients With X-Linked Hypophosphatemia: A Phase 3/4 Open-Label Trial.

ObjectiveBurosumab, an anti-fibroblast growth factor 23 antibody, was recently approved for the treatment of X-linked hypophosphatemia (XLH).We evaluated the safety and efficacy of burosumab in pediatric XLH patients.MethodsThis open-label, phase 3/4 trial of ≤ 124 weeks’ duration was conducted at 4 Japanese medical centers. Fifteen children aged 1 to 12 years with XLH were included. All had previously been treated with phosphorus or vitamin D. Subcutaneous burosumab was administered every 2 weeks, starting with 0.8 mg/kg, and adjusted based on serum phosphorus levels and any safety concerns (maximum 2 mg/kg). Safety assessments included the frequency of treatment-emergent adverse events (TEAEs). Efficacy of burosumab on biochemical markers, clinical markers of rickets, motor function, and growth was also evaluated.ResultsThe average treatment duration was 121.7 weeks. Frequently reported TEAEs were nasopharyngitis (46.7%), dental caries (40.0%), and influenza (33.3%). At baseline, patients had low serum phosphorus concentrations (2.6 ± 0.3 mg/dL) and low-to-normal 1,25-dihydroxyvitamin D concentrations (24.7 ± 12.7 pg/mL), which increased with burosumab treatment and were maintained during the study period. Alkaline phosphatase decreased continuously. At baseline, the mean ± SD total Thacher Rickets Severity Score (RSS) was 1.3 ± 1.2, and 4 patients (26.7%) had an RSS ≥ 2.0. Mean Radiographic Global Impression of Change and RSS tended to improve, particularly in patients with higher baseline RSS. There was a trend toward increased 6-minute walk test distance. No apparent changes in growth rate were observed.ConclusionBurosumab has a good safety profile and is effective in pediatric patients with XLH.

Biozote-p Application under Zero Tillage Drill Wheat Planting Influenced Yield and Phosphorus use Efficiency of Wheat Crop

The availability of phosphorus is limited in calcareous soil because of the chemical reaction between calcium and phosphorus by converting it into calcium phosphate. The application of phosphorus solubilizing bacteria as biofertilizer might help in the availability of phosphorus in soil. So, this study was aimed to enhance phosphorus use efficiency (PUE), growth, and yield of wheat planted by zero tillage drill after rice harvest using biozote-P as a microbial inoculant. Three treatments (T1 = Traditional wheat planting (control), T2 = Zero-tillage Drill wheat planting, and T3 = Zero-tillage Drill wheat planting + Biozote-P) were tested in the rice harvested field at Usta Muhammad, Balochistan during 2019-20. Each treatment was comprised of one acre and the collected data were subjected to descriptive statistics included minimum, maximum, mean, standard deviation, and standard error. The pre soil properties revealed that the soil was clayey, alkaline (pH>8.0) with low soil organic matter, total nitrogen, and available phosphorus contents. However, post soil properties showed increase in SOM with marginal level reduction in soil pH along with improvement in the availability of TN (0.051%) and P (4.31 mg kg-1) in T3. The ZT and ZT+Biozote-P increased grain yield by 32.09 and 36.94% over traditional wheat planting. So, phosphorus use efficiency (PUE) was increased by 41.77 and 29.22% in T3. It means that Biozote-P application under zero tillage drill improved PUE by 9.71% in comparison to sole zero tillage drill wheat planting. Subsequently, it is inferred that biozote-P (microbial inoculant) can be included in ZT wheat planting in rice-wheat cropping zone of Balochistan.

Calcium-modified granular attapulgite removed phosphorus from synthetic wastewater containing low-strength phosphorus

Traditional biological processes combined with chemical precipitation methods can effectively reduce phosphate concentration in wastewater. However, discharge standards required additional advanced treatment technologies, and the removal of low phosphorus concentration is complicated and expensive. This study proposes application of a simple and recyclable adsorbent to remove low-concentration phosphorus from water. The removal efficiency of phosphorus from low-strength synthetic wastewater was investigated and the adsorption mechanism was analyzed. When the initial phosphorus concentration was 2.0 mg/L, the phosphorus adsorption capacity of Ca-GAT increased to 0.891 mg/g from 0.074 mg/g for GAT at 298 K and pH of 7. Phosphorus adsorption on Ca-GAT performs well when the solution pH is in the range of 5–10, and it is not conducive to the adsorption reaction when the solution pH exceeds 11. The competing anions (such as NO3−, SO42−, HCO3− and F−) existed, Ca-GAT still performed better in removing phosphorus. Then, the saturated absorbents could be effectively regenerated with a 0.5 mos/L NaOH solution, while desorption efficiency was reduced from 97.11% to 33.06% after fifth regeneration cycle. Finally, Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the Ca2+ content on the Ca-GAT surface played an important role in capturing phosphate ions from wastewater. Phosphorus was mainly removed via the formation of Ca-phosphorus precipitation. To some extent, ligand exchanges of CO32− and OH- with HPO42− and H2PO4− were also beneficial for phosphorus removal. The present work shows that attapulgite has sustainable and beneficial potential in the removal of low-strength phosphorous in wastewater, and the phosphorus loaded adsorbent can be used in the agriculture as slow-release fertilizer.

The Influence of Kerosene on Microbiomes of Diverse Soils.

One of the most important challenges for soil science is to determine the limits for the sustainable functioning of contaminated ecosystems. The response of soil microbiomes to kerosene pollution is still poorly understood. Here, we model the impact of kerosene leakage on the composition of the topsoil microbiome in pot and field experiments with different loads of added kerosene (loads up to 100 g/kg; retention time up to 360 days). At four time points we measured kerosene concentration and sequenced variable regions of 16S ribosomal RNA in the microbial communities. Mainly alkaline Dystric Arenosols with low content of available phosphorus and soil organic matter had an increased fraction of Actinobacteriota, Firmicutes, Nitrospirota, Planctomycetota, and, to a lesser extent, Acidobacteriota and Verrucomicobacteriota. In contrast, in highly acidic Fibric Histosols, rich in soil organic matter and available phosphorus, the fraction of Acidobacteriota was higher, while the fraction of Actinobacteriota was lower. Albic Luvisols occupied an intermediate position in terms of both physicochemical properties and microbiome composition. The microbiomes of different soils show similar response to equal kerosene loads. In highly contaminated soils, the proportion of anaerobic bacteria-metabolizing hydrocarbons increased, whereas the proportion of aerobic bacteria decreased. During the field experiment, the soil microbiome recovered much faster than in the pot experiments, possibly due to migration of microorganisms from the polluted area. The microbial community of Fibric Histosols recovered in 6 months after kerosene had been loaded, while microbiomes of Dystric Arenosols and Albic Luvisols did not restore even after a year.

Understanding efficient phosphorus-functionalization of graphite for vanadium flow batteries

Numerous surface treatment methods are known to enhance the electrochemical activity of graphite felt (GF), such as thermal activation or attachment of nanoparticulate catalysts. The integration of heteroatoms into the graphite lattice at the surface could be a promising technique for reliable and efficient electrode activation. However, these functionalization techniques are based on thermochemical activation, which makes it difficult to distinguish between activity effects other than foreign atom integration, such as defects and other surface groups that must be considered. In this work, we analyzed commercial and synthetic phosphorus-doped graphene and GF using different electrochemical and physicochemical techniques. Despite a high doping concentration, the activity of the commercial powder bonded to GF and coated on glassy carbon remained limited due to the low degree of graphitization and high oxygen content. Instead, a low phosphorus concentration of <1 at% combined with a high degree of graphitization increased the catalytic activity. Building on these findings, GF was rationally modified, resulting in twice the power density compared to the original material in full cell tests.

ANALISIS SIFAT KIMIA TANAH PADA LAHAN HORTIKULTURA DI DESA LADOGAHAR KABUPATEN SIKKA

Soil is one of the main components that affect agricultural productivity. Soil quality certainly needs to be considered as an effort to increase plant growth and production. One of the most influential components of soil quality is the chemical nature of the soil. Research on Analysis of Soil Chemical Content in Horticultural Farmers' Land in Ladogahar Village, Nita District, Sikka Regency has been carried out from October to December 2021. The purpose of this study was to determine the chemical content of the soil in Horticultural Farmers' Land in Ladogahar Village, Nita District, Sikka Regency. This research uses observation methods, literature studies, and laboratory tests. Composite soil sampling using the zigzag method. The results showed that the land had a low C-organic content (1.00-2.00%), a slightly acidic pH (5.6-65), a low phosphorus content (21-40), and a Potassium content in the soil. moderate range (21-40).

Phosphorus puts a mortgage on restoration of species‐rich grasslands on former agricultural land

Large‐scale biodiversity loss is one of the most urgent global issues. The Convention on Biological Diversity created a vision to ecologically restore ecosystems by 2050. The European Union follows this ambition, and member states are required to select Special Areas of Conservation (SACs) to develop and restore; one example is species‐rich semi‐natural grassland. Species‐rich grassland restoration requires time for restoring both abiotic conditions, e.g. low soil phosphorus concentrations, and biotic conditions, e.g. introduction of missing species. For 507 grasslands (in northern Belgium) situated in SACs, we calculated the time needed for restoring necessary phosphorus‐poor conditions. Only 11% of the grasslands already met the strictest phosphorus‐target. We found that less than a fourth of the other 452 grasslands will reach this phosphorus‐target by 2050 through mowing. P‐mining, a more intensive technique involving fertilization of nitrogen and potassium, could help achieve this phosphorus‐target on about slightly more than a third of these grasslands by 2050. The soil iron concentration strongly affected the restoration times. A total of 65% of the grasslands will require alternatives like topsoil removal or selection of a different, less ambitious grassland target. These calculations do not include the time needed for biotic restoration. Because grassland restoration is a long‐term process, we advocate better protection of still existing species‐rich grasslands. Restoration is a last resort in safe‐guarding biodiversity.

Low level of phosphorous concentration in terminal Paleoproterozoic shallow seawater: Evidence from Chuanlinggou ironstone on North China Platform

Phosphorus (P) is a bio-limiting nutrient element, which through modulating marine primary productivity can influence ocean redox conditions. Precambrian, especially the mid-Proterozoic (1.8–0.8 Ga), seawater phosphorous concentrations have been poorly constrained. The well-preserved ∼1.65 Ga ironstones in North China provide a nice opportunity to explore the phosphorous concentrations of shallow seawater at that time. To avoid potential contamination we performed fabric-specific analysis of dense laminasets in ooid cortices without cracks, and in stromatolitic columns. These data revealed a low P/Fe molar ratio of 0.0007 ± 0.0003 (n = 12), pointing to an extremely low phosphorus concentration (<0.002–0.016 μM) in ∼1.65 Ga shallow seawater. If such a low phosphorus concentration is an universal phenomenon during terminal Paleoproterozoic, this is likely the significant reason for limited primary productivity and therefore a low atmospheric oxygen level during that time.

A Study of Phosphate Solubilizing Capacity by Penicillium Aurantiogriseum under Different Carbon and Nitrogen Resources

Phosphate-solubilizing fungi have been successfully applied to the release of phosphorus from insoluble tricalcium phosphate. A phosphate-solubilizing fungi Penicillium aurantiogriseum was isolated and investigated the phosphorus solubilizing capacity under different carbon and nitrogen resources. The highest released phosphorus content reached 1000 mg/L in ammonium and sucrose conditions. Carbon resources did not limit the release of phosphorus by Penicillium aurantiogriseum. However, nitrate and urea significantly reduced the phosphorus release, which had a low phosphorus content (~780 mg/L). Glucose and ammonium were more efficient for fungal growth and organic acid secretion. Oxalic acid secreted by Penicillium aurantiogriseum dominated the release of phosphorus. The formed calcium oxalate promoted the dissolution of tricalcium phosphate. This study indicated that the effective utilization of Penicillium aurantiogriseum to dissolve tricalcium phosphate need to support more ammonium nitrogen.

Changes in galling insect community on Caryocar brasiliense trees mediated by soil chemical and physical attributes.

The nutrient stress hypothesis predicts that galling insects prevail on host plants growing in habitats with soils of low nutritional quality. Caryocar brasiliense (Caryocaraceae) is host to four different leaf-galling insects. These insects have the potential to cause a reduction in the production of C. brasiliense fruits, an important source of income for many communities in Brazil. We studied the effects of soil physical and chemical characteristics on the abundance, species richness, and diversity of galling insects and their natural enemies on C. brasiliense trees growing under three different soil conditions. Our data corroborate the hypothesis that in nutritionally poor (e.g., lower phosphorus content) and worse physical textures (e.g., sandy) soils, host plants support higher species richness and diversity of galling insects. However, the abundance of Eurytoma sp. (the most common gall in C. brasiliense), was correlated with a higher phosphorus concentration in the soil (better nutritional condition). The percentage of galled leaflets and the area of leaflets occupied by Eurytoma sp galls were higher in the more fertile soil. In this soil, there was greater abundance, species richness, and diversity of parasitoids of Eurytoma sp. (e.g., Sycophila sp.) and predators (e.g., Zelus armillatus). Our data indicate the importance of habitat quality in the composition of the galling insect community and the impact of soil properties in mediating the distribution of these insects in C. brasiliense.

Development of bacterial resistance induced by low concentration of two-dimensional black phosphorus via mutagenesis.

The wide use of nano-antibacterial materials has triggered concerns over the development of nanomaterials-associated bacterial resistance. Two-dimensional (2D) black phosphorus (BP) as a new class of emerging 2D nanomaterial has displayed excellent antibacterial performance. However, whether bacteria repeatedly exposed to 2D BP can develop resistance is not clear. We found that wild type E. coli K-12 MG 1655 strains can increase resistance to 2D-BP nanosheets after repeated exposure with subinhibitory concentration of 2D-BP nanosheets. Adaptive morphogenesis including the reinforced barrier function of cell membrane were observed in the resistant bacteria, which enhanced the resistance of bacteria to 2D-BP nanosheets. The whole-genome sequencing analysis showed that the three mutation genes including dmdA, mntP, and gyrA genes were observed in the 2D-BP resistant strains, which controlled catabolism, membrane structure, and DNA replication, respectively. Furthermore, transcriptional sequencing confirmed that these genes related to metabolization, membrane structure, and cell motility were upregulated in the 2D-BP resistant bacteria. The development of resistance to 2D-BP in bacteria mainly attributed to the changes in energy metabolism and membrane structure of bacteria caused by gene mutations. In addition, the up-regulated function of cell motility also helped the bacteria to develop resistance by escaping external stimuli. The results provided new evidence for understanding an important effect of nano-antibacterial materials on the development of bacterial resistance.

Treatment of shrimp pond bottom sludge in Binh Dai district, Ben Tre province towards reuse as raw materials for organic fertilizer production

In this study, bottom sludge was collected from intensive shrimp ponds and aquaculture areas in Ben Tre province. The characteristics of the sludge sample taken to have a clay-meat texture, low organic matter, nitrogen, and total phosphorus content. Sludge from intensive shrimp ponds has very high salinity and solicitation (45-78%), useful nitrogen and useful phosphorus are quite rich, and heavy metal content as in shrimp pond sludge is low, below the threshold of contaminated soil. Polluted pollutants are recovered and treated in the direction of reuse as a source of raw materials for the production of organic fertilizers by aerobic decomposition using rice straw as a filler and incubated for 52 days. The results showed that the properties of the shrimp pond bottom sludge, which changed significantly during the composting process and contained nutritional elements, reached the required concentrations for organic fertilizers applied in Agriculture. After an incubation period of 52 days, the pH varied between 6.95 and 7.04. Humidity ranges from 52.1% to 68.3%. The temperature during composting fluctuates sharply: from 21.50C to 43.40C. Salinity decreased from 15.24 ppm to 12.36 ppm. The C/N ratio in the initial sludge sample was 8.64 and after incubation, it decreased to 6.4 (experiment 1 TN1); 7.6 (experiment 2 - TN2). After 52 days of incubation, the compost from shrimp pond bottom sludge had an organic composition of 15.6%, total nitrogen was 2.2%, and total phosphorus was 1.8%.

Effect of new pre-mix herbicides molecules on yield attributing character and yield of soybean [Glycine max (L.) Merrill] in vertisols

The experiment “Effect of new pre-mix herbicides molecules on yield attributing character and yield of soybean [Glycine max (L.) Merrill] in vertisols” was carried out during kharif season of 2017 at Instructional Cum Research Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh, with the objective to find out best pre-mix herbicide for growing soybean under the agro-climatic condition of Chhattisgarh. The soil in the experimental field was clayey (Vertisols) in texture, with low Nitrogen, medium phosphorus, and high potassium content. The experiment was laid out in randomized block design (RBD) having the combination of eight treatments replicated thrice. The weed management practices selected for study were T1 - Pendimethalin 30% EC+ Imazethapyr 2% SL premix @ 960 g a.i. ha-1 as PE, T2 - Sulfentrazone 48% F+ Clomazone 48 EC @ 725 g a.i. ha-1 as PE, T3- Diclosulam+ Pendimethalin 85% WG @ 102 g a.i. ha-1 as PPI, T4 - Diclosulam+ Pendimethalin 85% WG @ 127.5 g a.i. ha-1 as PPI, T5 - Imazethapyr 35% + Imazamox 35% WG @ 70 g a.i. ha-1 as PoE, T6 - Propaquizafop 2.5% + Imazethapyr 3.75% SL @ 50+75 g ai ha-1 as PoE, T7 – Pendimethalin @ 1000 g a.i. ha-1 as PE and T8 – control (weedy check). The results of experiment on response of different pre-mix herbicides revealed that yield attributing characters viz., number of pods plant-1, number of seeds pod-1, seed yield, stover yield and harvest index were significantly higher under treatments Propaquizafop 2.5% + Imazethapyr 3.75% SL @ 50+75 g ai ha-1 as PoE (T6). Similarly, all these characters were also superior in treatment of Sulfentrazone 48% F+ Clomazone 48 EC @ 725 g ai ha-1 as PE (T2). Remarkable lowest values were obtained in weedy check.

Drivers of the diversity of diatoms in an oligotrophic Andean stream

An in situ experiment determined that the addition of ammonia N-NH4+, nitrate N-NO3– and phosphate P-PO43– to an oligotrophic Andean stream significantly affected diatom composition and diversity. Over a nine-month period, fertilized and non-fertilized sections of the stream were studied for their environmental characteristics and diatom composition. Nutrient concentrations were increased three times in a downstream section with respect to those occurring naturally upstream. Alpha diversity (Shannon-Wiener [H”] and Simpson [S] indices) were determined monthly. In the non-fertilized control section, diatom diversity was significantly (p ≤ 0.05) related to water flow and P and N concentrations. In the fertilized section diversity was associated to the enhanced ammonia and phosphorus. A redundancy analysis (RDA) showed that conductivity, water flow and nutrient concentrations contributed to the diatom assemblage composition (83% along the first two axes). Achnanthidium minutissimum, Cocconeis placentula, and Epithemia sorex occurrence was related to low phosphorus concentration. Epithemia adnata var. minor, Nitzschia dissipata, and Reimeria sinuata were associated with high P concentrations, high water flow and low conductivity Navicula rynchocephala, Gomphonema parvulum, Navicula capitatoradiata, and Melosira varians were associated with high P.

Temporal declines in Wadden Sea phytoplankton cell volumes observed within and across species

AbstractCell size is a master trait in the functional ecology of phytoplankton correlating with numerous morphological, physiological, and life‐cycle characteristics of species that constrain their nutrient use, growth, and edibility. In contrast to well‐known spatial patterns in cell size at macroecological scales or temporal changes in experimental contexts, few data sets allow testing temporal changes in cell sizes within ecosystems. To analyze the temporal changes of intraspecific and community‐wide cell size, we use the phytoplankton data derived from the Lower Saxony Wadden Sea monitoring program, which comprises sample‐ and species‐specific measurements of cell volume from 1710 samples collected over 14 yr. We find significant reductions in both the cell volume of most species and the weighted mean cell size of communities. Mainly diatoms showed this decline, whereas the size of dinoflagellates seemed to be less responsive. The magnitude of the trend indicates that cell volumes are about 30% smaller now than a decade ago. This interannual trend is overlayed by seasonal cycles with smaller cells typically observed in summer. In the subset of samples including environmental conditions, small community cell size was strongly related to high temperatures and low total phosphorus concentration. We conclude that cell size captures ongoing changes in phytoplankton communities beyond the changes in species composition. In addition, based on the changes in species biovolumes revealed by our analysis, we warn that using standard cell size values in phytoplankton assessment will not only miss temporal changes in size, but also lead to systematic errors in biomass estimates over time.

Preparation of Magnetically Driven Nickel Phosphide Nanowires and Their Electrochemical Properties

In this study, nickel phosphide nanowires with various structures and compositions were fabricated for the first time via magnetically-assisted liquid phase synthesis. The curvature and aspect ratio of the nanowires largely depended on the strength of the magnetic field applied during synthesis. Their phosphorus content together with the morphology were significantly modified according to the pH and reducing agent concentration. Nanowires with different structures and phosphorus contents were preliminarily tested for their capabilities to serve in general electrochemical applications. The degree of reaction (i.e., amount of reaction charge) increased with increases in the reaction area and phosphorus content of the nanowires. The rate characteristics of the reaction showed a peculiar increasing trend for a small reaction surface area and low phosphorus content. A change in the ohmic overpotential according to the nanowire curvature (aspect ratio) and porosity was suggested to be the reason for this unusual trend. Electrodes with high phosphorus contents or high reaction surface areas rapidly deteriorated during repetitive redox reactions. Based on the results for the degradation degree, the effect of the reaction surface area dominated that of the phosphorus content in the deterioration of the nickel phosphide nanowires.

Phosphorus Export From Two Contrasting Rural Watersheds in the (Sub) Humid Ethiopian Highlands

Establishing worldwide sustainable and phosphorus efficient cropping systems is urgently needed because the supply of suitable phosphate rock is limited, and excess phosphorus in streams causes eutrophication. One of the impediments in the developing world for sustainable P practices is the lack of studies on P transport and its eventual disposition in the environment. One of these regions with few studies is the Ethiopian Highlands, with permeable volcanic soils. The objective was to establish baseline data on P watershed export in the (sub)humid highlands. Two contrasting watersheds were selected near Lake Tana. For 2 years, stream discharge and sediment, total P, dissolved P, and bioavailable particulate P concentrations were determined at the watershed outlet. The first watershed is the 57 km2 Dangishta, with lava intrusion dikes, forcing subsurface flow through faults to the surface and preventing gully formation. Subsurface flow was half of the 1745 mm annual precipitation, and surface runoff and erosion were minimal. The second watershed is the 9 km2 Robit Bata with 1,420 mm precipitation. The banks of several river banks were slumping. The upper part of the watershed generates saturation excess runoff. A hillslope aquifer in the lower part provided interflow. The average sediment concentrations of 10.5 g L−1 in the stream in Robit Bata (11 times that in Dangishta) reflected the sediments from banks slipping in the stream. The hydrology and the soil loss directly affected the phosphorus export. In Dangishta, the total P concentration averaged 0.5 mg L−1 at the outlet. In Robit Bata, the average total P concentration was 2 mg L−1. The bioavailable particulate P concentration was only twice the concentration in the runoff water. The low phosphorus content of the subsoil slipping in Robit Bata moderated biologically available particulate P at the outlet. Average dissolved P concentrations for both watersheds were around 0.1 mg L−1 in the low range found in temperate climates. It reflects the difference in length of time that phosphorus fertilizers have been applied. Our research concludes that commonly implemented practices such as strengthening river banks and stabilizing gully might not lead to improved water quality in Lake Tana.

Speciation and pH- and particle size-dependent solubility of phosphorus in tropical sandy soils

Growing demands for crops have expanded agricultural production to sandy soils with low available phosphorus (P) content and high P mobility. Knowledge of P speciation and solubility in such soils is poorly understood. Here we investigated: i) the P speciation in the clay size fraction of sandy soils, ii) the pH-dependent solubility of soil orthophosphate (PO4–P), and iii) the particle size-dependent solubility of the soil P. The studied loamy sand soils were low in organic matter (2.6–7.9 g kg−1) and deficient in available P (1.5–8.5 mg kg−1), and kaolinite (21%) was the only clay mineral identified using X-ray diffraction technique in the clay-sized particles. The P K-edge X-ray absorption near edge structure analysis revealed that P associated with Al phases, 45% adsorbed to gibbsite and 35% in variscite (AlPO₄·2H₂O), dominated the P speciation in the clay-sized particles. The very low PO4–P solubilities in the investigated bulk soils exhibited a pronounced positive pH-dependent pattern that was consistent with the pH-dependent solubility of Al3+ and Fe3+. Geochemical modeling suggested that the maximum PO4–P solubilities were linked to the solubility of variscite and strengite (FePO₄·2H₂O), indicating that PO4–P solubilities were controlled by the solubility of Al3+ and Fe3+ as restricted by the pH-dependent solubility of Al phases and Fe (hydr)oxides. The analysis of particle size fractions revealed that the largest size fraction (1000–2000 µm), containing visible plant debris and contributing the least to total soil mass (<0.126%), contained most of the total soil P stocks (50–60%). The small size factions (<250 µm) were the key to available PO4–P. Our data highlighted the pivotal role of Al/Fe (hydr)oxides and kaolinite in controlling the pH-dependent solubility of PO4–P in these tropical sandy soils having very limited contents of total and available P and a high risk of P loss.

Growth and Nutrient Uptake Characteristics of Heterosigma akashiwo (Raphidophyceae) under Nitrogen and Phosphorus Concentrations in the East China Sea

Heterosigma akashiwo is classified as a harmful algal bloom (HAB) species that frequently occurs in eutrophic coastal waters and results in the contamination and mortality of fish and shellfish. The growth of H. akashiwo in four phosphate and nitrate concentration scenarios, representing the observed nutrient concentration ranges in the East China Sea (ECS), was evaluated to further understand the effect of nutrient concentrations on H. akashiwo blooms. The specific growth rate in the exponential growth phase (µ′) and the maximum cell density were lower (17–21% and 41%, respectively) under low phosphorus concentration scenarios, compared to the rates observed under high phosphorus concentration scenarios. The cellular nitrogen-to-phosphorus ratios of H. akashiwo were influenced by the initially supplied N:P ratio and the allocation strategy employed. Phosphorus concentration had a greater influence on the total growth of H. akashiwo than nitrate did, within the natural nutrient conditions of the ECS. These results could serve as a reference for coastal water management and marine ecological management and may be useful for further studies on the simulation and prediction of H. akashiwo blooms, particularly in the ECS.

Enzymatic Degumming of Rice Bran Oil Using Different Commercial Phospholipases and Their Cocktails.

Rice bran oil is a highly nutritious vegetable oil, as it is rich in tocols and γ-oryzanol. Degumming is the first step in the vegetable oil refining process, and its main objective is the removal of phospholipids or gums. In the present study, enzymatic degumming trials were performed on crude rice bran oil using the phospholipases PLA1, Purifine® PLC, their mixture (PLA1/PLC), and a cocktail known as Purifine® 3G. Enzymatic degumming applying 50 mg/kg of PLA1 for 120 min resulted in a residual phosphorus content of 10.4 mg/kg and an absolute free fatty acid increase of 0.30%. Enzymatic degumming applying 300 mg/kg of Purifine® PLC for 120 min at 60 °C resulted in a residual phosphorus content of 67 mg/kg and an absolute diacylglycerol increase of 0.41%. The mixture of phospholipases and the cocktail presented approximately 5 mg/kg of residual phosphorus content after the reaction times. For all degumming processes, the preservation of minor components such as tocols and γ-oryzanol were observed. These results indicate that the use of enzyme mixtures or their cocktails to attain low phosphorus content and high diacylglycerol/free fatty acid conversion during enzymatic degumming is a viable alternative.