Phosphorus Turnover Research Articles

Changes in Phosphorus Turnover and Microbial Communities of Two Kenyan Soils

Changes in Phosphorus Turnover and Microbial Communities of Two Kenyan Soils

Validating novel oligonucleotide primers targeting three classes of bacterial non-specific acid phosphatase genes in grassland soils

Microbially driven mineralization of organic phosphorus forms is of particular importance in the soil environment, where it becomes available to plants as inorganic orthophosphates. In acidic soils, microbes produce non-specific acid phosphatases (NSAPs; E.C. 3.1.3.2) which act on the most common forms of organic P in the soil. Our understanding of phosphorus turnover in soils would greatly benefit from an improvement in research tools targeting these genes. Thus, in this study we developed two novel oligonucleotide PCR primer sets, that will enable researchers to target the present and active communities of bacteria with the genetic potential of acid phosphatase production. A total of three primer sets were validated to target the three classes of NSAPs. Utilizing Illumina MiSeq, amplicons from grassland pasture soils were sequenced. The resulting target specificity was high for all three groups; CAAP (97.2%), CBAP (99.5%), and CCAP (94.8%). Quantification of target genes by qPCR indicated measurable differences between classes, ranging from 5 log to 7.5 log for CAAP, 6 log to 8 log for CBAP, and 4 log to 5 log for CCAP. The validated primer sets were specific to the target genes and identified potential quantitative differences between the NSAP classes.

Turnover of carbon and phosphorus in the microbial biomass depending on phosphorus availability

Adjustment of the mean residence time (MRT) of elements in the soil microbial biomass (SMB) might be an important process by which microbial communities adapt to nutrient-poor environments and maintain their element biomass ratio. Yet, little is known about the turnover of elements such as carbon (C) and phosphorus (P) in the SMB, which is partly due to methodological challenges. This is the first study to determine the MRT of C and P in SMB based on labeling of microbial DNA with 14C and 33P. We studied the MRT of C and P in the SMB of topsoil from a temperate, mesic grassland fertilized with five different amounts of P. For this purpose, soil was labeled with 14C-glucose and 33P-phosphate and incubated for 24 h, and then, 14C and 33P in the soil microbial DNA were determined. The MRT of C and P was calculated based on the C and P content of DNA, and the observation that soil microbial biomass C and microbial DNA are linearly correlated. The SMB-C and the MRT of C in the SMB were not affected by P availability, whereas the microbial community significantly increased the MRT of P in its biomass from 18.1 to 39.0 days with decreasing P availability. Our results indicate that the adjustment of the MRT of individual elements in the SMB is an important process by which microbes adapt to nutrient poor environments and are able to maintain their biomass element ratio when decomposing substrate with a very high C-to-nutrient ratio.

Phosphorus mobilization in the Yeyahu Wetland: Phosphatase enzyme activities and organic phosphorus fractions in the rhizosphere soils

Phosphatase enzymes regulate organic phosphorus (OP) turnover in eutrophic wetland soils, but a clear understanding of their relationships remains elusive. In this study, soil samples were collected from rhizosphere and non-rhizosphere soils of three dominant aquatic plants Phragmites communis, Zizania latifolia, and Scirpus planiculmis in Yeyahu Wetland of Beijing, China to investigate the phosphatase enzyme activities, including phosphomonoesterase, phosphodiesterase and phytase, and the impact on OP turnover dynamics in wetlands. Results demonstrated that soil phosphatase activities in rhizosphere were higher than those in non-rhizosphere for all the three plants. Phosphatase activities were correlated strongly with soil labile organic P, although the relationships showed different trends for the three kinds of phosphatases. Moderate liable organic P had a positive correlation to phosphomonoesterase (r = 0.367, P < 0.01) and phosphodiesterase (r = 0.564, P < 0.01). There was a significant negative correlation between highly resistant organic P and phytase (r = −0.438, P < 0.05), indicating that phytase had obvious effects on the process of degrading highly stable P compounds in soils. These results suggest that phosphatase enzymes regulated OP turnover to increase available P and phytase had a strong impact on wetland P cycle system.

Long-term fertilisation regimes affect the composition of the alkaline phosphomonoesterase encoding microbial community of a vertisol and its derivative soil fractions

Alkaline phosphomonoesterase (ALP) mainly originates from soil microbial secretion and plays a crucial role in the turnover of soil phosphorus (P). To examine the response of ALP-encoding microbial communities (analysed for the biomarker of the ALP gene, phoD) of soils and derivative soil fractions to different fertilisation regimes, soil samples were collected from a long-term experimental field (over 35 years). The different organic P (Po) pools of soil fractions and the ALP activity of soil were also determined. Compared with chemical-only fertilised soils, the ALP activity was 232–815% higher in organic-amended soils, and the highest enzyme activity was observed in the organic-only fertilised treatment. The abundance of the phoD gene harbouring in soil fractions, determined by quantitative PCR (qPCR), was affected by different fertilisations. The highest abundance of the phoD gene was generally detected in the 2–63-μm-sized fraction (silt), but most phoD-encoding microbial species were associated to the 0.1–2-μm-sized fraction (clay) in the chemical-only fertilised soil. The contents of labile Po (LPo), moderately labile Po (MLPo) and fulvic acid-associated Po (FAPo) were significantly correlated with the phoD gene abundance, whereas only LPo content was significantly correlated with the ALP activity. The dominant phoD-encoding phylas were Actinobacteria and Proteobacteria, according to a high-throughput sequencing. Bradyrhizobium, a N2-fixer identified as a phoD-encoding genus, showed the highest abundance in fertilised soils. The abundance of Bradyrhizobium, Streptomyces, Modestobacter, Lysobacter, Frankia and Burkholderia increased with the organic-only amendment and was significantly correlated with the ALP activity. According to structure equation models (SEM), pH and LPo content significantly and directly affected the ALP activity; the soil organic C (Corg) content was related to composition and abundances of phoD-harbouring microbial communities; since both microbial properties were correlated to the ALP activity, the Corg content was indirectly related to the ALP activity. In conclusion, soil management practices can be used to optimise the contents of soil available P and the organic P with regulation of soil ALP activity and the community composition of corresponding microbes.

Novel oligonucleotide primers reveal a high diversity of microbes which drive phosphorous turnover in soil

Phosphorus (P) is of central importance for cellular life but likewise a limiting macronutrient in numerous environments. Certainly microorganisms have proven their ability to increase the phosphorus bioavailability by mineralization of organic-P and solubilization of inorganic-P. On the other hand they efficiently take up P and compete with other biota for phosphorus. However the actual microbial community that is associated to the turnover of this crucial macronutrient in different ecosystems remains largely anonymous especially taking effects of seasonality and spatial heterogeneity into account. In this study seven oligonucleotide primers are presented which target genes coding for microbial acid and alkaline phosphatases (phoN, phoD), phytases (appA), phosphonatases (phnX) as well as the quinoprotein glucose dehydrogenase (gcd) and different P transporters (pitA, pstS). Illumina amplicon sequencing of soil genomic DNA underlined the high rate of primer specificity towards the respective target gene which usually ranged between 98% and 100% (phoN: 87%). As expected the primers amplified genes from a broad diversity of distinct microorganisms. Using DNA from a beech dominated forest soil, the highest microbial diversity was detected for the alkaline phosphatase (phoD) gene which was amplified from 15 distinct phyla respectively 81 families. Noteworthy the primers also allowed amplification of phoD from 6 fungal orders. The genes coding for acid phosphatase (phoN) and the quinoprotein glucose dehydrogenase (gcd) were amplified from 20 respectively 17 different microbial orders. In comparison the phytase and phosphonatase (appA, phnX) primers covered 13 bacterial orders from 2 different phyla respectively. Although the amplified microbial diversity was apparently limited both primers reliably detected all orders that contributed to the P turnover in the investigated soil as revealed by a previous metagenomic approach. Genes that code for microbial P transporter (pitA, pstS) were amplified from 13 respectively 9 distinct microbial orders. Accordingly the introduced primers represent a valuable tool for further analysis of the microbial community involved in the turnover of phosphorus in soils but most likely also in other environments.

Impact of land use and nutrient addition on phosphatase activities and their relationships with organic phosphorus turnover in semi-arid grassland soils

Information on the relationships between phosphatase activities and organic phosphorus (P) turnover is fundamental to understanding soil P dynamics but remains poorly understood. An 8-year field study was conducted in a steppe and an abandoned cropland under semi-arid grasslands to explore the effects of nitrogen (N) and P additions on P composition in soil as determined by 31P nuclear magnetic resonance (NMR) and associated phosphatase activities. Results showed that the phosphate monoester content, soil acid phosphomonoesterase, alkaline phosphomonoesterase, and phosphodiesterase activities were higher in the steppe than in the abandoned cropland soil. Nitrogen addition significantly suppressed phosphatase activities. Phosphorus addition significantly increased acid phosphomonoesterase, alkaline phosphomonoesterase, and phosphodiesterase activities in the steppe but significantly decreased them in the abandoned cropland. Structural equation modeling revealed that both phosphodiesterase and alkaline phosphomonoesterase activities showed significant negative effects on diesters and monoesters in the steppe, but there were no significant effects of phosphatase activities on organic P composition in the abandoned cropland. Our findings highlight the variation of dominant mechanisms involved in organic P turnover with land use change. Phosphorus deficiency in the steppe appeared to promote the production of phosphatases and the subsequent biochemical mineralization of organic P. While in the abandoned cropland, previous cultivation resulted in a proportionally greater loss of soil organic carbon than that of organic P, indicating that organic P was mineralized as a result of biological mineralization of organic matter.

In situ stable isotope probing of phosphate-solubilizing bacteria in the hyphosphere.

This study used a [(13)C]DNA stable isotope probing (SIP) technique to elucidate a direct pathway for the translocation of (13)C-labeled photoassimilate from maize plants to extraradical mycelium-associated phosphate-solubilizing bacteria (PSB) that mediate the mineralization and turnover of soil organic phosphorus (P) in the hyphosphere. Inoculation with PSB alone did not provide any benefit to maize plants but utilized the added phytate-P to their own advantage, while inoculation with Rhizophagus irregularis alone significantly promoted shoot biomass and P content compared with the control. However, compared with both sole inoculation treatments, combined inoculation with PSB and R. irregularis in the hyphosphere enhanced organic P mineralization and increased microbial biomass P in the soil. There was no extra benefit to plant P uptake but the hyphal growth of R. irregularis was reduced, suggesting that PSB benefited from the arbuscular mycorrhizal (AM) fungal mycelium and competed for soil P with the fungus. The combination of T-RFLP (terminal restriction fragment length polymorphism) analysis with a clone library revealed that one of the bacteria that actively assimilated carbon derived from pulse-labeled maize plants was Pseudomonas alcaligenes (Pseudomonadaceae) that was initially inoculated into the hyphosphere soil. These results provide the first in situ demonstration of the pathway underlying the carbon flux from plants to the AM mycelium-associated PSB, and the PSB assimilated the photosynthates exuded by the fungus and promoted mineralization and turnover of organic P in the soil.

Phosphatase activity and phosphorus turnover rate in Lakes Ladoga and Onega

The rates of inorganic phosphorus regeneration and the alkaline and acid phosphatase activities in Lakes Ladoga and Onega have been determined. The rate of phosphorus turnover in the eutrophic areas of Lakes Ladoga and Onega ranges from 1 to 4 hours.

Phosphorus Removal With Grass In An Apple Orchard Under Influence Of Mulch And Irrigation

Phosphorus leaching from intensive agriculture systems is one of major contributors responsible for pollution of ground-water and surface water bodies. The aim of this study was to determine the content of phosphorus in orchard lawn for reduction of phosphorus fertilizer application and to include the phosphorus from mown grass into P balance and turnover calculation. The investigation was done at the Latvia State Institute of Fruit–Growing in 2009. Three treatments were compared: control, mulch and fertigation. Inter-row strips were covered by grass vegetation. Grass samples were collected at the time of grass mowing. The removal of phosphorus was calculated as kilograms per hectare area. The concentration of phosphorus in the lawn and the height of grass growth were significantly influenced by the mowing time and the soil moisture treatment. These results can be a base for further studies of phosphorus turnover in an orchard, as well as for fertilizer planning and management.

Characterization of phosphorus in marshland sediments by 31phosphorus nuclear magnetic resonance spectroscopy

Phosphorus turnover is vital to understand algal blooms and nutrient export in coastal waters; however, little is known about the composition and dynamic of sediment phosphorus in marshes. In this study, the relative composition of various organic phosphorus in sodium hydroxide (NaOH) extracts of freshwater and saltwater sediments in the Pelham Bay Park, New York City, the USA, were investigated, using solution 31phosphorus nuclear magnetic resonance Spectroscopy. The correlation between sodium hydroxide-extractable organic phosphorus and the organic matter content fitted to a linear model. Moreover, it is indicative that the species of organic phosphorus compounds in sediments are mainly dependent on salinity and the organic matter content in the sediments. The representative phosphorus compounds in the marshland sediments were glucose-6-phosphate nucleoside monophosphate and dihydroxyacetone phosphate. The composition of various phosphorous compounds was more complex in the saltwater sediments than in the freshwater sediments. Monoester phosphorus was the major component in most of the marshland, and diester phosphorus dominated the anoxic area.

Turnover and losses of phosphorus in Swedish agricultural soils: long-term changes, leaching trends, and mitigation measures.

Transport of phosphorus (P) from agricultural fields to water bodies deteriorates water quality and causes eutrophication. To reduce P losses and optimize P use efficiency by crops, better knowledge is needed of P turnover in soil and the efficiency of best management practices (BMPs). In this review, we examined these issues using results from 10 Swedish long-term soil fertility trials and various studies on subsurface losses of P. The fertility trials are more than 50 years old and consist of two cropping systems with farmyard manure and mineral fertilizer. One major finding was that replacement of P removed by crops with fertilizer P was not sufficient to maintain soil P concentrations, determined with acid ammonium lactate extraction. The BMPs for reducing P leaching losses reviewed here included catch crops, constructed wetlands, structure liming of clay soils, and various manure application strategies. None of the eight catch crops tested reduced P leaching significantly, whereas total P loads were reduced by 36% by wetland installation, by 39 to 55% by structure liming (tested at two sites), and by 50% by incorporation of pig slurry into a clay soil instead of surface application. Trend analysis of P monitoring data since the 1980s for a number of small Swedish catchments in which various BMPs have been implemented showed no clear pattern, and both upward and downward trends were observed. However, other factors, such as weather conditions and soil type, have profound effects on P losses, which can mask the effects of BMPs.

Bacterial Community Features Are Shaped by Geographic Location, Physicochemical Properties, and Oil Contamination of Soil in Main Oil Fields of China.

Geographic location and physicochemical properties are thought to represent major factors that shape soil bacterial community abundance and diversity. Crude oil contamination is becoming a notable concern with respect to soil property variation; however, the quantifiable influences of geographic location, physicochemical properties, and oil contamination are still poorly understood. In this study, the 16S ribosomal RNA genes of bacteria in the four oil fields in China were analyzed by using pyrosequencing. Results showed that physicochemical properties were the most dominant factor of bacterial community distribution, followed by geographical location. Oil contamination was a driving factor whose indirect influence was stronger than its direct influence. Under the impact of these three factors, different oil fields presented diversified and distinguishable bacterial community features. The soil of sites with the highest total petroleum hydrocarbon content (HB), nitrogen content (DQ), and phosphorus content (XJ) contained the largest proportion of functional groups participating in hydrocarbon degradation, nitrogen turnover, and phosphorus turnover, respectively. The first dominant phylum of the site with loam soil texture (HB) was Actinobacteria instead of Proteobacteria in other sites with sandy or sandy loam soil texture (DQ, SL, XJ). The site with the highest salinization and alkalization (SL) exhibited the largest proportion of unique local bacteria. The site that was located in the desert with extremely low precipitation(XJ) had the most diversified bacteria distribution. The bacterial community diversity was strongly influenced by soil physicochemical properties.

A revised semi-empirical mass balance model for phosphorus in Baltic coastal areas

A decade of research on the phosphorus dynamics in Baltic Sea coastal areas using a combination of mathematical modelling, sediment surveys and time series of water quality data from monitoring programs has led to an improved understanding of processes controlling phosphorus turnover and coastal primary production. This paper presents a revised model for phosphorus turnover in non-tidal enclosed Baltic coastal areas. Using a new dataset from 500 sediment sampling stations it was possible to quantify and develop new simplified algorithms for sedimentary processes i.e. burial and erosion that did not decrease the model's predictive power. Our results indicate that erosion of old clays can be an important primary source to phosphorus water concentrations in enclosed coastal areas. A simple laboratory experiment using Common Duckweed (Lemna minor) supports to some extent that phosphorus originating from old clays is partly bioavailable and hence may influence the trophic state in the studied areas.

Extraction and quantification of phosphorus derived from DNA and lipids in environmental samples

Understanding the flux and turnover of phosphorus (P) in the environment is important due to the key role P plays in eutrophication and in the ambition to find cost-effective measures to mitigate it. Orthophosphate diesters, including DNA and phospholipids (PLs), represent a potentially degradable P pool that could support future primary production and eutrophication. In this study, extraction techniques were optimized and combined with colorimetric determination of extracted P to provide a selective quantification method for DNA-P and PL-P in agricultural soil, sediment and composted manure. The proposed method is rapid and reproducible with an RSD of <10%. Recovery, evaluated by spiking the sample matrices with DNA and PL standards, was over 95% for both DNA and PLs. The method can be used for the determination of the pool size of the two organic P fractions. Results show that DNA-P comprises 3.0% by weight of the total P (TP) content in the studied soil, 10.4% in the sediment and 8.4% in the compost samples. The values for PL-P are 0.5%, 6.0% and 1.7% for soil, sediment and compost, respectively.

Steady‐state bioassay approach applied to phosphorus‐limited continuous cultures: A growth study of the marine chlorophyte Dunaliella salina

Phosphorus‐limited growth and phosphate uptake kinetics of the marine phytoplankter Dunaliella salina were studied using continuous‐culture techniques. Determination of residual phosphate concentrations in the cultures were made using a steady‐state bioassay approach in which short‐term phosphate uptake rates as measured by 33P‐radiotracer were balanced with the turnover of phosphorus in the culture. This allowed the determination of low‐nanomolar ambient phosphate concentrations (8–95 nmol P L−1) at seven unique specific growth rates, which agreed closely with an alternative kinetics bioassay phosphate determination. The relationship of specific growth rate to ambient phosphate concentration for the D. salina cultures was well‐described by the Monod growth equation with μmax = 1.8 d−1 and Kμ = 28 nmol P L−1. Phosphate uptake kinetics were evaluated at three growth rates and adhered to Michaelis‐Menten kinetics, with evidence of growth‐rate‐dependent variability of uptake affinities (1.9–3.0 L µmol−1 h−1) and half‐saturation constants (1.85–3.8 µmol P L−1). Maximum uptake rates were constant across growth rates when measured in either carbon‐specific (220 µmol P mol C−1 min−1), volume‐specific (7 amol P µm−3 min−1), cell‐specific (1 fmol P cell−1 min−1), or phosphorus‐specific units (7 h−1). This represents a phosphate uptake rate capacity between 200‐fold and 600‐fold greater than the requirements for growth. Finally, we compared the results from our study with previous studies across four phytoplankton species and found that the Monod half‐saturation constant for phosphorus‐limited growth (Kμ) is well‐predicted by the theoretical ratio of the maximum specific growth rate to the phosphorus‐specific uptake affinity.

The cycling of readily available phosphorus in response to elevated phosphate in acidic temperate deciduous forests

The biogeochemical cycling of phosphorus (P) in temperate forest ecosystems is poorly understood relative to nitrogen (N) cycling because of the assumption that N is the main factor that limits plant growth. This dichotomous way of understanding nutrient regimes is likely an oversimplification of these dynamic, interacting cycles within the evermore-dynamic framework of soil development. In order to better understand P cycling in temperate deciduous forests, we sought to quantify labile (resin) P flux and determine if soil shows signs of P stress. Labile P flux was quantified in nine ambient and nine elevated P plots on unglaciated eastern deciduous forests in Eastern Ohio. Anion exchange membranes (AEMs) were deployed in situ for two weeks, in the fall and the winter. Flux values were contextualized by resin P pools, N and P mineralization, and phosphatase enzyme activities determined from soil samples collected both at the time of AEM deployment and harvest. Phosphorus flux was 0.64±0.23μgPd−1 (mean±SD) in ambient plots and 3.47±2.39μgPd−1 in amended P plots. Resin P pools were 4.16mgkg−1 and 10.26mgkg−1 in the control and elevated plots, respectively. Phosphorus turnover rate increased from one week in control plots, to 3 days in elevated P plots. Results indicate mild P stress relative to N, as N was mineralized (0.84±0.18mgNkg−1d−1) while P was immobilized (−0.22±0.09mgPkg−1d−1). The elevated P treatment did not increase P mineralization. Phosphatase enzyme activities were significantly suppressed by 34% with P amendment. Results suggest labile P is a shallow pool, but is rapidly cycling.

Studying the response of Lake Ladoga ecosystem to a decrease in phosphorus load

A study of the transformation of Lake Ladoga ecosystem in 1996–2005 shows that a decrease in the phosphorus load after 1995 has not cause a decrease in lake ecosystem productivity. Mathematical modeling provided an explanation of the observed phenomenon, thus justifying limnologists’ hypothesis that phosphorus turnover within a water body accelerates with increasing abundance of bacterioplankton and aquatic fungi. Computational experiments have shown that the additional amount of phosphorus that is required for maintaining phytoplankton productivity is additionally released by destructors (bacterioplankton and aquatic fungi) from detritus and organic matter dissolved in water.

Phosphate exchange across the sediment-water interface under oxic and hypoxic/anoxic conditions in the southern Baltic Sea

Abstract Benthic fluxes of phosphate and phosphorus distribution in sediments from the southern Baltic Sea were investigated in spring and autumn in 2005 and 2007–2010. Strong spatial variability of phosphate fluxes was observed across the sediment-water interface. The highest values of phosphate flux from sediment (up to 37 μmol m−2 h−1), resulting from the high mineralization rate of organic matter and rapid phosphorus turnover due to macrofaunal activity and hydrodynamic conditions, were observed in the shallow area at depths ranging from 50 to 69 m. The rate of phosphate exchange in the transportation and accumulation bottom area with the water depth ≥72 m was several times lower (2.12–6.22 μmol m−2 h−1). In continuously hypoxic or anoxic sediments, phosphorus was preserved in the refractory organic form, and sediments were depleted of redox-dependent phosphorus forms. In shallow area with well oxygenated near-bottom water, phosphorus was present mainly in the calcium-bound form.

Assessing turnover of microbial biomass phosphorus: Combination of an isotopic dilution method with a mass balance model

Abstract Microbial biomass phosphorus (P) can play an important role in P cycling and availability to plants by acting as a source (remineralization) or sink (immobilization) of phosphate ions (iP). To assess the role of the microbial P pools, both the dynamics (i.e. the turnover) and the size of the microbial P pools were studied in forest soils. Combining an isotopic dilution method with a modelling approach, we showed the existence of two pools of microbial P with different dynamics and therefore of different importance in soil P availability and cycling. In particular, we showed that the largest pool of microbial P (80%) had a fast turnover (nine days). Microbial P increased with an increase in soil organic matter and represented up to 53% of total P in contrasting forest soils. By combining these results with the turnover times of microbial P obtained in the modelling study, we evaluated that 8.5–17.3 kg P ha −1 of microbial P could turn over in a few days. This suggests that microbial biomass P is a potentially significant source of available iP, and that micro-organisms can play a major role in P cycling in the forest studied here. However, microbial biomass can also be in competition with the trees since most of the remineralized P could be immobilized again in the microbial turnover.