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Soil phosphorus (P) partitioning could contribute to species diversity and structure in plant communities, but field-scale evidence for P partitioning remains scarce. We hypothesized that the presence of P partitioning could be inferred from statistical associations between the spatial distributions of plants and chemical forms of bioavailable soil P. We investigated this in a diverse tropical tree community on Barro Colorado Island, Panama. We quantified potentially bioavailable forms of soil P by extraction in 2 mM citric acid followed by treatment with phosphatase enzymes. We then linked these P forms to the distribution of 189 tree species in a 50 ha forest dynamics plot by testing species–P associations against null models of random dispersal. We found that 20% of tree species were significantly (α = 0.05) associated with the depletion of at least one soil organic P fraction, although around half of these associations might be false rejections of the null hypothesis due to type I error. Species in the Fabaceae (legumes), which are known to express high rates of phosphatase in their roots, were most frequently associated with soil P fractions. We interpret our findings as evidence of widespread P partitioning at the community scale, affecting a relatively small proportion of tree species in this moderately fertile forest. We predict that stronger evidence of partitioning will be found at sites with lower P availability. [ABSTRACT FROM AUTHOR]

Earthworms can increase the solubility of phosphorus (P) in soil, an effect which to a large extent is controlled by mineralisation of organic P. Phosphatases, a class of hydrolytic enzymes, catalyse this mineralisation process. However, a consistent comparison of their activity among earthworm species and for different soil spheres is still missing. Here we aim to better understand the activity of phosphatases in relation to earthworm-enhanced P-availability, and specifically that of phosphomonoesterases (PME) which directly liberate orthophosphate. We conducted a greenhouse pot experiment with five different earthworm species. The PME activity was assessed in earthworm casts, burrows and bulk soil for both single species and mixed communities. Analyses were performed at both the pH-H2O of the bulk soil (6.5) and of the casts (7.5). The PME activity measured at both pH values was highly correlated (R2 = 0.98; p = 2.2x10-16) and was strongly elevated by earthworm activity in the order cast > burrows > bulk soil. The PME activity was particularly high in the casts of A. longa relative to casts of other species. Large variation in PME activity in the drilosphere was observed among earthworm species, but this variation was not related to earthworm ecological categories. Our data also indicate that an elevated P concentration in grass shoots could result from increased PME activity via greater hydrolysis of organic P.

The objective of this study was to investigate the effects of different rates of straw returning on soil aggregate stability, phosphatase activities, and the available nitrogen (N) and phosphorus (P) within different soil aggregate sizes. The experiment included five treatments: 1) no straw returning and no chemical fertilizer, 2) chemical fertilizer only (150 kg N ha-1, 75 kg P ha-1, and 75 kg K ha-1), 3) 20% straw returning with chemical fertilizer, 4) 60% straw returning with chemical fertilizer, and 5) 100% straw returning with chemical fertilizer. Soil samples were collected 3.5 years after the start of the experiment and separated into four aggregate sizes (

In order to reveal the microbial processes regulating the responses of soil organic phosphorus (P) mineralization to nitrogen (N) addition, abundances of 3 soil bacterial phosphatase-encoding genes (phoC, phoD and appA)and corresponding acid phosphomonoesterase, alkaline phosphomonoesterase and phytase activities, as well as related soil physiochemical properties were measured in a Pinus sylvestris var. mongolica plantation that has subjected to 10 years of field N addition (100 kg N ha-2year-1). The results show that N addition reduced acidic and alkaline phosphomonoesterase activities in the soil of Pinus sylvestris var. mongolica plantation by 18.09% and 55.29%, and the phytase activity decreased by 41.88%. Nitrogen addition reduced the copy number of each gene by 40.97% (16S-rRNA), 78.38% (phoD), 67.92% (phoC), and 74.37% (appA), respectively. The proportion of the copy number of functional gene in the total bacterial gene 16S-rRNA decreased significantly by 61% (phoD), 44% (phoC), and 55% (appA). The contents of soil microbial biomass carbon and microbial biomass phosphorus were significantly positively correlated with the activities of acid phosphomonolipase, alkaline phosphomonoesterase, phytase and gene abundances of 16S rRNA, phoD, phoC and appA. Soil ammonium nitrogen content was significantly negatively correlated with the activities of acid phosphomonoesterase and alkaline phosphomonoesterase, as well as the abundance of 16S rRNA, phoC and appA genes. The activity of acid phosphomonoesterase was significantly positively correlated with its gene abundance, and the other two enzyme activities had no significant correlation with its gene abundance.The above results indicate that the N addition not only reduced abundance of soil phosphatedissolving bacteria, but also reduced the proportion of phosphate-dissolving bacteria in the total bacteria, thereby greatly reduced phosphatase activities and depressed organic phosphorus mineralization. [ABSTRACT FROM AUTHOR]

Drought is significant abiotic stress that affects the development and yield of many crops. The present study is to investigate the effect of arbuscular mycorrhizal fungi (AMF) and biochar on root morphological traits, growth, and physiological traits in soybean under water stress. Impact of AMF and biochar on development and root morphological traits in soybean and AMF spores number and the soil enzymes' activities were studied under drought conditions. After 40 days, plant growth parameters were measured. Drought stress negatively affected soybean growth, root parameters, physiological traits, microbial biomass, and soil enzyme activities. Biochar and AMF individually increase significantly plant growth (plant height, root dry weight, and nodule number), root parameters such as root diameter, root surface area, total root length, root volume, and projected area, total chlorophyll content, and nitrogen content in soybean over to control in water stress. In drought conditions, dual applications of AMF and biochar significantly enhanced shoot and root growth parameters, total chlorophyll, and nitrogen contents in soybean than control. Combined with biochar and AMF positively affects AMF spores number, microbial biomass, and soil enzyme activities in water stress conditions. In drought stress, dual applications of biochar and AMF increase microbial biomass by 28.3%, AMF spores number by 52.0%, alkaline phosphomonoesterase by 45.9%, dehydrogenase by 46.5%, and fluorescein diacetate by 52.2%, activities. The combined application of biochar and AMF enhance growth, root parameters in soybean and soil enzyme activities, and water stress tolerance. Dual applications with biochar and AMF benefit soybean cultivation under water stress conditions. [ABSTRACT FROM AUTHOR]

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Drought is significant abiotic stress that affects the development and yield of many crops. The present study is to investigate the effect of arbuscular mycorrhizal fungi (AMF) and biochar on root morphological traits, growth, and physiological traits in soybean under water stress. Impact of AMF and biochar on development and root morphological traits in soybean and AMF spores number and the soil enzymes’ activities were studied under drought conditions. After 40 days, plant growth parameters were measured. Drought stress negatively affected soybean growth, root parameters, physiological traits, microbial biomass, and soil enzyme activities. Biochar and AMF individually increase significantly plant growth (plant height, root dry weight, and nodule number), root parameters such as root diameter, root surface area, total root length, root volume, and projected area, total chlorophyll content, and nitrogen content in soybean over to control in water stress. In drought conditions, dual applications of AMF and biochar significantly enhanced shoot and root growth parameters, total chlorophyll, and nitrogen contents in soybean than control. Combined with biochar and AMF positively affects AMF spores number, microbial biomass, and soil enzyme activities in water stress conditions. In drought stress, dual applications of biochar and AMF increase microbial biomass by 28.3%, AMF spores number by 52.0%, alkaline phosphomonoesterase by 45.9%, dehydrogenase by 46.5%, and fluorescein diacetate by 52.2%, activities. The combined application of biochar and AMF enhance growth, root parameters in soybean and soil enzyme activities, and water stress tolerance. Dual applications with biochar and AMF benefit soybean cultivation under water stress conditions.

Buffers are widely used when performing soil enzyme assays, either to measure specific soil enzyme activities based on a standard protocol or to determine the pH optima of a soil enzyme. However, few studies have tested whether the existent buffer-making protocol they followed actually obtains the target pH during their enzyme assays. To test the pH stabilization capacity of modified universal buffer (MUB) commonly used in soil enzyme assays, four different soils with varying buffering capacity (proxied by contrasting soil pH and clay content) were used for phosphomonoesterase assays using a 1:5 (m/v) soil:buffer ratio, as per common practice for chromogenic enzyme assays. The original MUB working solution deviated from the target pH by as much as 1.6 units. Deviations were greatest when the soil and buffer had contrasting pH. Increasing MUB concentration by fourfold did not mitigate this pH discrepancy to a satisfactory level (± 0.1 unit). For the standardly used MUB concentration (1 ×), the deviation between the target pH and the assay pH was greatest when the difference between the target pH and the soil pH was > 1 unit. Therefore, forcing pH to a specific value in soil enzyme activity assays (1:5 soil:MUB) appears to be difficult for many soils, and increasing MUB concentration risks reducing enzyme activities due to higher ionic strength. Thus, the use of MUB to assay enzyme activity presents a tension between maintaining the target pH and maximizing the sensitivity of the assay. [ABSTRACT FROM AUTHOR]

We investigated spatiotemporal variations of nutrients, dissolved organic pools (C, N, P), phosphomonoesterase (PME) and phosphodiesterase (PDE) activities, heterotrophic prokaryotic production and planktonic microorganisms within the mixed layer (ML) in the Eastern Mediterranean Sea. We characterized two contrasted situations: autumn 2018 (highly stratified period, deep chlorophyll maximum within 100 m depth) and winter 2019 (including a bloom period). We compared the distribution of biogeochemical variables within the mixed layer and hydrological vertical structure between the different stations using a principal component analysis. Six groups of stations were identified (one group in autumn, 5 in winter), based on variable physical descriptors but also environmental biogeochemical conditions related to i) the seasonal aspect (for instance, all stations sampled within the Ierapetra anticyclone in autumn clustered in one, single group); ii) transitions between cyclonic and anticyclonic structures with a large range of ML depths (18–269 m) and indications of intense, preceding winter convection events: iii) progression of a high phytoplankton bloom during the winter cruise inferred from a series of observations: a strong nitrate drawdown, important growth of Synechococcus , pico and nano eukaryotes, accumulation of chlorophyll a (>60 mg m−2), primary production rates up to 509 mg C m−2 d−1, changes in the pigments' diversity, increase in biomass-specific ectoenzymatic activities and of heterotrophic prokaryotic production, all in conjunction with the vicinity of the Rhodes gyre. Here, we studied the distribution of biological and biogeochemical properties within the mixed layer, in particular by employing sensitive methods for the detection of low phosphate concentrations and of the labile dissolved organic phosphorus pool. From this data set, we demonstrate that the surface mixed layer classically considered as a P-depleted and uniform layer in the Eastern Mediterranean Sea was highly biologically dynamic, and prone to rapid spatio-temporal changes in phosphatase activities and phytoplankton dynamics. Altogether, these data reveal a strong short-term population dynamics. The results highlight the role of mixing episodes in winter, which provide pulsed supplies of phosphate and/or nitrate from the deeper layer to the euphotic zone, triggering transient blooms that often go undetected by satellites. • Significant role of mixing episodes in winter in eastern Mediterranean Sea. • Meso-scale variability in the mixed layer (P-depleted) affects P cycle and populations. • Phosphomonoesterase and phosphodiesterase kinetics tracers of P availability. • An important, winter phytoplankton bloom evidenced in the vicinity of the Rhodes gyre. • Highest cell specific phosphatases were seen in the Rhodes gyre. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is a finite and pivotal resource in determining plant yield. Intercropping with legumes is frequently proposed to improve P nutrition in many crops such as wheat, and the greater yield and P uptake observed are mostly attributed to legumes' root exudation of organic acids and phosphatases, which modify rhizosphere chemistry. The same rhizosphere modification drives the selection of specific bacterial communities by providing carbon sources such as organic acids and other metabolites. This study aimed to further understand the influence of P bioavailability on bacterial community selection and whether this can be extended to other crops through intercropping. Pea, lupin and wheat were grown as intercrops and as sole crops at four levels of P availability. This was achieved by using a low-P soil from the long-term experiment at Rothamsted Research, amended with available and low-available forms of P. After 62 days of growth, 16S rRNA gene amplicon sequencing was performed from rhizosphere samples, and acid and alkaline phosphomonoesterase (PME) activity was measured. The plant species was the main factor determining the structure of the bacterial community followed by P availability. When P was unavailable or depleted, legume monoculture as well as intercropping, was associated with reduced bacterial species richness and diversity, which was partly explained by an increased relative abundance of Variovorax , Pseudomonas and Bradyrhizobium spp. The complexity and interconnections of the bacterial community were increased in intercropping when P was unavailable as was alkaline PME activity, while the acid PME activity was more affected by the plant. In conclusion, wheat intercropping can generate a more complex and interconnected root-associated bacterial community, which can potentially contribute to the facilitation of P uptake. • Pea and lupin shape the rhizosphere microbial community due to P availability. • Alpha diversity is lower in the rhizosphere of legumes, than in wheat and bulk soil. • The selection of rhizobacteria is extended from legumes to wheat by intercropping. • At unavailable P, communities are more complex and interconnected in intercropping. • Alkaline phosphatase activity is higher in intercropping and when P is unavailable. [ABSTRACT FROM AUTHOR]

Background and aims: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of Quercus serrata, which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for Quercus serrata to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME. The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in Q. serrata. This regulatory mechanism may allow Q. serrata to grow across a wide soil P gradient.Methods: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of Quercus serrata, which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for Quercus serrata to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME. The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in Q. serrata. This regulatory mechanism may allow Q. serrata to grow across a wide soil P gradient.Results: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of Quercus serrata, which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for Quercus serrata to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME. The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in Q. serrata. This regulatory mechanism may allow Q. serrata to grow across a wide soil P gradient.Conclusion: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of Quercus serrata, which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for Quercus serrata to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME. The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in Q. serrata. This regulatory mechanism may allow Q. serrata to grow across a wide soil P gradient. [ABSTRACT FROM AUTHOR]

Background: Phosphoprotein phosphatases (PPP) belong to the PPP Sequence family, which in turn belongs to the broader metallophosphoesterase (MPE) superfamily. The relationship between the PPP Sequence family and other members of the MPE superfamily remains unresolved, in particular what transitions took place in an ancestral MPE to ultimately produce the phosphoprotein specific phosphatases (PPPs). Methods: We use structural and sequence alignment data, phylogenetic tree analysis, sequence signature (Weblogo) analysis, in silico protein-peptide modeling data, and in silico mutagenesis to trace a likely route of evolution from MPEs to the PPP Sequence family. Hidden Markov Model (HMM) based iterative database search strategies were utilized to identify PPP Sequence Family members from numerous bacterial groups. Results: Using Mre11 as proxy for an ancestral nuclease-like MPE we trace a possible evolutionary route that alters a single active site substrate binding His-residue to yield a new substrate binding accessory, the “2-Arg-Clamp”. The 2-Arg-Clamp is not found in MPEs, but is present in all PPP Sequence family members, where the phosphomonesterase reaction predominates. Variation in position of the clamp arginines and a supplemental sequence loop likely provide substrate specificity for each PPP Sequence family group. Conclusions: Loss of a key substrate binding His-in MPEs opened the path to bind novel substrates and evolution of the 2-Arg-Clamp, a sequence change seen in both bacterial and eukaryotic phosphoprotein phosphatases.General significance: We establish a likely evolutionary route from nuclease-like MPE to PPP Sequence family enzymes, that includes the phosphoprotein phosphatases.

Marine microbes use extracellular phosphatases to hydrolyze phosphate from organic matter. Dissolved organic phosphorus (DOP) is typically present in higher concentrations than phosphate in oceanic surface waters. Yet, the fate and role of different DOP components, such as phosphomonoester and phosphodiester, are poorly understood. Most of the investigations on extracellular enzymatic hydrolysis of marine DOP have focused on phosphomonoesterase (MEA) activity (i.e., alkaline phosphatase), whereas phosphodiesterase (DEA) measurements are scarce. This limits our understanding of the ecological and biogeochemical role of DOP sources other than P-monoesters in the sea. We determined extracellular MEA and DEA activities including their cell-free fractions on a bimonthly basis over 14 months in surface and mesopelagic subantarctic waters, thus covering a wide range of phosphate availability levels (from 70%) of extracellular MEA and DEA was found in the cell-free fraction, increasing with depth for MEA. Our results indicated that DOP hydrolysis mediated by DEA in the surface as well as in dark ocean is as important as the frequently measured MEA.

The production of enzymes involved in lignin degradation (laccase, ligninase), carbon cycling (β-glucosidase), and phosphorous cycling (phosphomonoesterase) by white rot fungi (Pleurotus sajor-caju) was studied. In the presence of chlorpyrifos, carbofuran, and their mixture, laccase activity was highest on the 7th day, i.e., 192.5 ± 0.31 U ml− 1, 213.6 ± 0.31 U ml− 1, and 164.6 ± 0.31 U ml− 1, respectively, compared to the control which produced maximum laccase on the 14th day (126.9 ± 0.15 U ml− 1). Phosphomonoesterase activity in the presence of chlorpyrifos, carbofuran, and their mixture was 31.5 ± 0.25, 24.1 ± 0.15, and 29.2 ± 0.35 µg PNP min−1 ml−1, respectively, which was more than the control on the 21st day (11.63 ± 0.21 µg PNP min−1 ml−1). β-Glucosidase production increased with the days of incubation in the presence of pesticides than in the control. β-Glucosidase activity on the 21st day in the presence of chlorpyrifos, carbofuran, and their mixture was 32.4 ± 0.1, 24.2 ± 0.3, and 28.4 ± 0.25 µg PNP min−1 ml−1, respectively, as compared to control (15.3 ± 0.6 µg PNP min−1 ml−1). Thus, chlorpyrifos, carbofuran, and their mixture were found to have a positive effect on the production of laccase, β-glucosidase, and phosphomonoesterase by P. sajor-caju, which can use these pesticides as a source of their nutrition, thereby improving the health of pesticide-polluted soils. [ABSTRACT FROM AUTHOR]

Excessive amounts of sewage sludge produced in sewage treatment plants along with the ban on its storage and dumping require rapid solutions to the problem of sewage sludge management. An example of a rational and environmentally viable method may be provided by its application in agriculture and environmental management. The optimal solution is to use sludge as a fertiliser for industrial plants, including energy crops, that is, those not used in food production. For environmental reasons it is essential to control soil quality and condition following sludge application. Analyses of the residual effect of sewage sludge and bacteria, actinobacteria, fungi microbial inoculant (BAF) on selected physiological parameters of plants and microbial activity of soil were conducted in the years 2013–2015 on experimental fields of the Poznan University of Life Sciences. The results indicate that the application of sewage sludge increased yields and improved selected photosynthesis activity and biometric traits of willow. Among the tested combinations the best results were obtained following the application of sewage sludge combined with the BAF medium microbial inoculant. Similar dependencies were observed when evaluating soil microbial activity.

Aims: We aimed to quantify the pool size of soil microbial biomass P (Pmic) during the early stage of soil development up to 125 years after glacial retreat in the Gongga Mountains, China and relate the pool size of Pmic to the plant P (Pplant) pools in the ecosystem. Methods: We determined the pool sizes of P in soil microbes, plants and soils and the P fluxes with plant uptake and litterfall in successional ecosystems at five study sites along the 125-year Hailuogou glacial retreat chronosequence. Moreover, we estimated the flux of P cycled through microbial biomass (Pmic cycling) based on literature data. We also approached the likelihood of P competition between plants and soil microbes based on the P status of the plants, soils and soil microbes. Results: The size of the Pmic pools (0.2–8.3 g m−2) in the organic layer and top 10 cm of the mineral soils was comparable to that of the Pplant pools (0.3–9.1 g m−2) at all study sites along the Hailuogou chronosequence. Based on the literature, the Pmic cycling at our study site (0.3–13.5 g m−2 year−1 if estimated based on temporal fluctuations of Pmic, 5.2–268 g m−2 year−1 if estimated based on the isotope dilution method) was at least one order of magnitude larger than the Pplant uptake (not detected-0.36 g m−2 year−1) and the Pplant return by litterfall (not detected-0.16 g m−2 year−1). Although Pmic became a major pool of biological P, we did not find indications of P competition between plants and soil microbes as indicated by the positive relationships between the concentrations of Pmic and plant-available P in soils and the P-rich status of plants and soil microbes. Conclusions: Soil microbial biomass already becomes a major P pool in the early stage of soil development. Our estimations based on the literature suggest that Pmic cycling is probably the largest P flux in the studied up to 125-year ecosystems. Plants likely did not suffer P competition with microbes, in part due to the preferential decomposition of the P-rich compounds from dead microbial biomass which led to net P mineralization. [ABSTRACT FROM AUTHOR]

The monitoring of atmospheric nitrogen deposition is necessary considering that this kind of environmental pollution is among the leading causes of global biodiversity loss. However, deploying and operating monitoring networks can be cost-prohibitive; the use of naturally occurring biomonitors can be a viable alternative for characterizing such nitrogenous pollution, with bryophytes being of particular promise. For instance, a previous dose-response greenhouse experiment evaluating potential biomonitors of different life-forms revealed that the activities of the enzymes phosphomonoesterase and nitrate reductase respond linearly to simulated nitrogen deposition for the generalist neotropical moss Braunia secunda. The present work is the field validation of B. secunda and Leptodontium pungens, a specialist of oak forests, as biomonitors of nitrogen deposition. Moss samples were collected during the 2009 dry and rainy seasons from fir and oak forests at "low-pollution" or "high-pollution" sites within the Valley of Mexico, where the megalopolis of Mexico City is located, and transported to the laboratory for colorimetric determinations of enzymatic activity. The phosphomonoesterase activity was consistently higher for both mosses from the high-pollution sites than for the low-pollution sites, while the nitrate reductase had a lower activity for the plants collected from the high-pollution sites. These results suggest that the proposed biomonitors are appropriate for the region of study. [ABSTRACT FROM AUTHOR]

In a field experiment in Palmira, Colombia, we studied mycorrhizal root colonization, phosphomonoesterase activities and P and N foliar content before and after N fertilization among different Brachiaria genotypes with demonstrated biological nitrification inhibition (BNI) capacity. Furthermore, we tested the potential nitrification rate (PNR) in soil in order to confirm the inhibition of nitrification of the selected genotypes and relate the BNI performance with P acquisition. We hypothesized that (i) genotypes will differ in key variables related to P acquisition, and that there will be a positive correlation between (ii) arbuscular mycorrhizal fungi (AMF) root colonization, P uptake, and BNI activity, and (iii) between the activity of acid and alkaline phosphomonoesterase and BNI performance. Higher N immobilization 1 week after application of synthetic fertilizer (ammonium sulfate) and low PNR of Brachiaria humidicola CIAT 679 and CIAT 16888 confirmed that these genotypes have high-BNI activity. Despite the relatively high soil P status, high affinity of Brachiaria grasses for AMF was observed at the study site: more than 60% of root length was colonized by AMF in high-BNI genotypes, versus 45% in low-BNI Brachiaria cv. Mulato. The N content of high-BNI genotypes was positively correlated with mycorrhizal root colonization suggesting the uptake of NH4+ by AMF and its transfer to high-BNI genotypes and/or regulation of AMF colonization by P demand. Furthermore, increased activity of acid phosphomonoesterase (6.98 and 7.68 μmol g−1 h−1 in high-BNI versus 5.20 μmol g−1 h−1 in low-BNI genotypes) and the depletion of the most labile available P fractions in the rhizosphere of high-BNI genotypes (by 21–32%) suggest enhanced P uptake and P-use efficiency. To the best of our knowledge, this is the first study that explored relations between BNI and biotic factors affecting P acquisition. Our results highlight the importance of AMF in Brachiaria grasses even under high P availability and warrant further studies including a larger number of different BNI genotypes that can elucidate biotic plant-soil interactions affecting nutrient-use efficiencies in improved pastures under low and high P status. [ABSTRACT FROM AUTHOR]

Excessive amounts of sewage sludge produced in sewage treatment plants along with the ban on its storage and dumping require rapid solutions to the problem of sewage sludge management. An example of a rational and environmentally viable method may be provided by its application in agriculture and environmental management. The optimal solution is to use sludge as a fertiliser for industrial plants, including energy crops, that is, those not used in food production. For environmental reasons it is essential to control soil quality and condition following sludge application. Analyses of the residual effect of sewage sludge and bacteria, actinobacteria, fungi microbial inoculant (BAF) on selected physiological parameters of plants and microbial activity of soil were conducted in the years 2013-2015 on experimental fields of the Poznan University of Life Sciences. The results indicate that the application of sewage sludge increased yields and improved selected photosynthesis activity and biometric traits of willow. Among the tested combinations the best results were obtained following the application of sewage sludge combined with the BAF medium microbial inoculant. Similar dependencies were observed when evaluating soil microbial activity. [ABSTRACT FROM AUTHOR]

Assays of enzyme activities in soil samples based on para -nitrophenol ( p NP) spectrophotometry are a powerful tool in soil biochemistry. We evaluated potential sources of error and optimization strategies for soil enzyme assays across 12 diverse soils (6 USDA orders, 31–127 mg g −1 soil organic carbon [SOC]), using the activity of soil phosphomonoesterase (PHO) as an example. We hypothesized that dissolved organic matter (DOM) interference, p NP recovery, and substrate concentration would affect calculated enzyme activities, and that this would reflect the method of assay termination: 0.5 M NaOH + 0.5 M CaCl 2 (Tabatabai, 1994), 0.2 M NaOH + 2.0 M CaCl 2 (Schneider et al., 2000), 0.5 M NaOH + 2.0 M CaCl 2 (this study), and 0.1 M Tris (pH 12) + 0.5 M CaCl 2 (Klose et al., 2003). Terminations using 0.5 M NaOH increased p NP recovery compared to termination with 0.1 M Tris, but resulted in greater DOM interference (absorbance at 410 nm), which for terminations using NaOH but not Tris was positively correlated with total SOC (R 2 = 0.45–0.38). Greatest DOM interference occurred for Andisols for termination with 0.5 M NaOH + 0.5 M CaCl 2 , which for two Andisols of intermediate SOC (97 and 68 mg g −1 ) was 1–2 orders of magnitude greater than other soils (346 and 246% overestimation of PHO activity). Increasing CaCl 2 concentration (0.5 M–2.0 M) decreased DOM interference, but this effect was less pronounced than the effects of base type or concentration. Enzyme activity tended to be overestimated in assays terminated with NaOH due to DOM interference, and was more greatly underestimated in assays terminated with Tris buffer due to low recovery of p NP, which was soil-specific. Soil PHO K m values, which were not correlated with SOC, varied by soil (4.2–13.3 mM g −1 soil) demonstrating that substrate concentrations routinely employed (typically ≤ 10 mM g −1 soil) are likely insufficient to achieve recommended substrate conditions (5 × K m ) for accurate measurement of PHO activity. This study illustrates the importance of a priori determination of soil enzyme K m to achieve conditions nearing substrate saturation, and recommends termination with 0.2 M NaOH + 2.0 M CaCl 2 , correction for p NP recovery, and correction for DOM absorbance at 410 nm to increase the accuracy of p NP-based enzyme assays in soils. Finally, to improve communication and thus comparison of measured enzyme activities among studies and assay methods ( p NP vs 4-methylumbelliferone [MUF]), it is suggested that studies report the concentration of substrate for the final volume used in enzyme assays, report K m values on a soil mass basis, express enzyme activities on a molar p NP basis, and qualify enzyme activities, K m , and V max as ‘apparent’ if corrections for interferences are not performed. [ABSTRACT FROM AUTHOR]

Previous meta-analyses revealed that the ratio of activities of carbon (C)-acquiring enzyme to nitrogen (N)-acquiring enzymes in tropical forest ecosystems was nearly identical to those in other ecosystems, despite of the N-rich condition in tropical forests. This could be explained by microbes in tropical forest soils, which require a large amount of N to produce N-rich acid phosphatase (AP) for catalyzation of the organic form of phosphorus (P) and compensation for poor P availability in soils. Based on this idea, we hypothesized that experimental P fertilization would reduce the allocation to N-acquiring enzymes compared with that of C-acquiring enzymes, i.e. that it would increase the ratios of activities of β-1,4-glucosidase (BG) to β-1,4-acetylglucosaminidase (NAG) and leucine aminopeptidase (LAP). We tested this hypothesis using an experimental fertilization site with factorial N (100 kg ha−1 yr−1) and P (50 kg ha−1 yr−1) addition in a primary tropical lowland forest in Bornean Malaysia, where our earlier work demonstrated that P fertilization reduced AP activity. Contrary to our hypothesis, the BG:NAG and BG:(NAG + LAP) ratios were not altered by either N or P fertilizations. This result indicated that AP production was not a reason for the maintenance of a relatively high investment in N-acquiring enzyme at our study site. Rather, NAG and LAP production was likely driven by C acquisition, rather than N acquisition, as the target substrates contained C as well as N. This idea was supported by the fact that neither the BG:NAG ratio nor the BG:(NAG + LAP) ratio was elevated by N addition. We propose that the ratios of activities of BG to NAG and LAP do not necessarily indicate the ratio of C:N acquisition, at least in our N-rich tropical forest ecosystem. [ABSTRACT FROM AUTHOR]

Among our collection of psychrophilic bacteria from various non-polar glaciers, the present study involves the study of the ability of the psychrophilic bacterial strains, isolated from Passu Glacier, Pakistan, to produce thermolabile alkaline phosphatase extracellularly as well as intracellularly. The biophysio-chemical characteristics and 16S rRNA signatures of the isolate MRLBA1 were similar to the members of genus Pseudomonas. This rod shaped MRLBA1 isolated from glacial ice exhibited aerobic growth cycle with cardinal limits of pH; 4-11 and temperature; 2-30°C. The strain showed highest extracellular alkaline phosphatase activity at pH 8.0 and 18°C when inoculated with 24 h old inoculum (5%), after 48 h of incubation in shake flask at 150 rpm. The strain’s targeting mechanism of alkaline phosphatase at cell membrane as well as in the extracellular medium is interesting. The results demonstrated that alkaline phosphatase being thermolabile, acts as a stress protein also in addition to harvesting the energy directly in carbon deficient ice. [ABSTRACT FROM AUTHOR]

The relations between anthropogenic environmental pollution and the level of inorganic phosphorus in soil, enzyme activities of extracellular soil acid phosphatase and the surface acid phosphatase of excised ectomycorrhizas of Scots pine (Pinus sylvestris L.) were studied. Soil and root samples were taken from two Scots pine stands in central Poland: a polluted site exposed to long-term pollution from a steelworks and the city of Warsaw and a reference plot (control) free from direct impact of pollution. The polluted site was characterised by high concentration of trace elements (Cd, Pb, Cu, Zn, Mn, Cr) and low level of inorganic phosphate in soil. This site had significantly lower enzyme activities of soil acid phosphatase (0.54 µmoles p-nitrophenol released g-1 dry weight h-1) and surface acid phosphatase of pine ectomycorrhizas (3.37 µmoles p-nitrophenol released g-1 fresh weight h-1) than the control site (1.36 µmoles p-nitrophenol released g-1 dry weight h-1 and 12.46 µmoles p-nitrophenol released g-1 fresh weight h-1, respectively). The levels of phosphate, carbon and nitrogen in pine fine roots were also analysed. Low concentrations of P04-P and high N: P ratio in pine fine roots from polluted site were found. The results suggest that soil pollutants may have a negative effect on the extracellular acid phosphatase of soil and Scots pine ectomycorrhizas and on the phosphorus status in fine roots of the plant.

The abundance of nitrogen (N)-fixing plants in ecosystems where phosphorus (P) limits plant productivity poses a paradox because N fixation entails a high P cost. One explanation for this paradox is that the N-fixing strategy allows greater root phosphatase activity to enhance P acquisition from organic sources, but evidence to support this contention is limited., We measured root phosphomonoesterase ( PME) activity of 10 N-fixing species, including rhizobial legumes and actinorhizal Allocasuarina species, and eight non-N-fixing species across a retrogressive soil chronosequence showing a clear shift from N to P limitation of plant growth and representing a strong natural gradient in P availability., Legumes showed greater root PME activity than non-legumes, with the difference between these two groups increasing markedly as soil P availability declined. By contrast, root PME activity of actinorhizal species was always lower than that of co-occurring legumes and not different from non-N-fixing plants., The difference in root PME activity between legumes and actinorhizal plants was not reflected in a greater or similar reliance on N fixation for N acquisition by actinorhizal species compared to co-occurring legumes., Synthesis. Our results support the idea that N-fixing legumes show high root phosphatase activity, especially at low soil P availability, but suggest that this is a phylogenetically conserved trait rather than one directly linked to their N-fixation capacity. [ABSTRACT FROM AUTHOR]

It is becoming more apparent that increased organic nutrient loads deriving from anthropogenic activities and natural processes frequently cause the eutrophication of coastal waters. Concurrently, an increasing number of phototrophs have been shown to make use of organic nutrients, mainly through indirect studies of surface enzyme activities or through direct studies of growth in media containing organic-only nutrients. The potential utilization of dissolved organic phosphorus (DOP) by microepiphytic-mats associated with frequently problematic, toxic dinoflagellate Ostreopsis cf. ovata , was investigated throughout a full cycle of a bloom that occurs annually (over the last few decades) during summer along several stretches of the Mediterranean coast. Measurements of phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities of the epiphytic mats (including cells and exopolymeric substances) and a range of chemico-physical parameters were made from late summer to early autumn at a eutrophic site. Analyses of ambient nutrient fractions revealed very high aquatic N:P values (TN:TP = 178 ± 50), very low filterable reactive P (FRP) concentrations (13 out 19 under the limits of detection) and DOP concentrations that were on average 85% of the total dissolved P. We recorded a rapid increase in PMEase and PDEase activities in the epiphytic microalgal community that coincided with the onset of a proliferation of the Ostreopsis population. Chromogenic staining of samples showed that activity was closely associated with the Ostreopsis cells, located both extracellularly (cell surface and within the EPS) and intracellularly (ventral cytoplasm). The increase in both phosphatases indicates that Ostreopsis can utilise a wide range of DOP types. The intense activity in the EPS was suggested to aid in the efficient entrapment and processing of high concentration nutrient pulses, for extracellular processing of larger organic materials and to prevent loss of substrates and products to the surrounding water. Based on the present findings, Ostreopsis seems to have adaptations that allow it to thrive in P-limited environments where organic P is the main source of P. [ABSTRACT FROM AUTHOR]

Aims: Soil hydrolysable P can be a main P source for biota in P-limited tropical rain forests. Soil hydrolysable P occurs in various chemical fractions, including, monoester P, diester P, pyrophosphate and phytate, which need enzymatic hydrolysis into orthophosphate before their assimilation into biota. We examined whether P-limited plants and microbes preferentially hydrolyzed specific fraction of soil hydrolysable P and whether those in different successional stages had different abilities to hydrolyze various soil hydrolysable P. Methods: We measured four classes of phosphatase (phosphomonoesterase, PME; phosphodiesterase, PDE; pyrophosphatase, PyP; and phytase, PhT) activities for fine-roots and soils in nitrogen (N) and P fertilized primary and secondary tropical rain forests in Sabah, Malaysia. Results: P fertilization reduced PME, PyP and PhT activities for fine-roots and PME and PyP activities for soils. Fine-roots in primary forests had higher PME and PyP activities whereas those in secondary forests had higher PhT activities. Conclusions: We suggest that P-limited trees and microbes depend more on hydrolysable P degraded by one step of enzymatic reaction (monoester P, pyrophosphate, and phytate) as a P source. We also suggest that trees have different soil-organic-P acquisition strategies in association with their life history strategies. [ABSTRACT FROM AUTHOR]

We characterized the vertical distribution of extracellular phosphatase enzymes; phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities in sediments of three subtropical lakes were characterized by different trophic states. We then explored relationships between phosphatase activities, phosphorus (P) compounds, and microbial biomass and activity. Sediment P compounds had been characterized previously by two different methods: sequential fractionation and solution P NMR spectroscopy. PMEase and PDEase activities declined with depth and were correlated strongly with microbial biomass and anaerobic respiration, indicating that bacterial phosphatase dominated in these sediments and is an important step in the anaerobic breakdown of organic matter. The oligo-mesotrophic lake had higher PMEase activity and the hypereutrophic lake had higher PDEase activity, while the eutrophic lake had the lowest activities of both enzymes. Principal component analyses showed that enzyme activities were related closely to concentrations of the P forms that they degrade: PMEase activity was correlated with phosphomonoesters, while PDEase activity was correlated with phosphodiesters (including nucleic acids and phospholipids). Enzyme activities were not related to the trophic state but with the concentration P forms found in the sediment. Overall, these results provide insight into the phosphorus cycle in subtropical lake sediments by demonstrating a link between phosphatase activity, P composition, and microbial activity. [ABSTRACT FROM AUTHOR]

Ubiquitous presence along with uncontrolled use of aluminum and increasing trends of ethanol consumption in India increased the chance of coexposure to aluminum and ethanol. Possibilities are there, that both of them follow common mechanisms to produce neurotoxicity. The phosphomonoesterases and glutamate transaminases are studied in rat brain cerebrum after combined exposure to aluminum and varied doses of ethanol for 4 weeks. Dose dependent decreases in growth have been observed. The impact of aluminum on cerebral acidic and alkaline phosphomonoesterases activities were shown to be altered in a dose dependent fashion by the coexposure to ethanol. Aspartate aminotransferase and alanine aminotransferase of the cerebrum were responding differentially to aluminum exposure in the presence of different doses of ethanol exposure. It has been suggested that the ethanolinduced augmentation of impacts of aluminum on the cerebrum is dose dependent and there might be a critical level of ethanol exposure for the observed effect on cerebrum. .

Motivated by decreasing foliar phosphorus (P) concentrations in Fagus sylvatica L. forests, we studied P recycling depending on P fertilization in mesocosms with juvenile trees and soils of two contrasting F. sylvatica L. forests in a greenhouse. We hypothesized that forests with low soil P availability are better adapted to recycle P than forests with high soil P availability. The P resorption efficiency from senesced leaves was significantly higher at the P-poor site (70 %) than at the P-rich site (48 %). P fertilization decreased the resorption efficiency significantly at the P-poor site to 41 %, while it had no effect at the P-rich site. Both acid and alkaline phosphatase activity were higher in the rhizosphere of the P-poor than of the P-rich site by 53 and 27 %, respectively, while the activities did not differ in the bulk soil. Fertilization decreased acid phosphatase activity significantly at the P-poor site in the rhizosphere, but had no effect on the alkaline, i.e., microbial, phosphatase activity at any site. Acid phosphatase activity in the P-poor soil was highest in the rhizosphere, while in the P-rich soil, it was highest in the bulk soil. We conclude that F. sylvatica resorbed P more efficiently from senescent leaves at low soil P availability than at high P availability and that acid phosphatase activity in the rhizosphere but not in the bulk soil was increased at low P availability. Moreover, we conclude that in the P-rich soil, microbial phosphatases contributed more strongly to total phosphatase activity than plant phosphatases. [ABSTRACT FROM AUTHOR]

We investigated whether three different types of moss transplants (devitalized moss bags with and without cover and auto-irrigated moss transplants) are suitable for use as biomonitors of the deposition of oxidised and/or reduced forms of N. For this purpose, we determined whether the concentration of atmospheric NO 2 was related to the % N, δ 15 N and the activity of the enzyme biomarkers phosphomonoesterase (PME) and nitrate reductase (NR) in the tissues of moss transplants. We exposed the transplants in 5 different environments of Galicia (NW Spain) and Cataluña (NE Spain): industrial environments, urban and periurban environments, the surroundings of a cattle farm and in a monitoring site included in the sampling network of the European Monitoring Programme. The results showed that the moss in the auto-irrigated transplants was able of incorporating the N in its tissues because it was metabolically active, whereas in devitalized moss bags transplants, moss simply intercepts physically the N compounds that reached it in particulate or gaseous form. In addition, this devitalization could limit the capacity of moss to capture gaseous compounds ( i.e. reduced N) and to reduce the oxidised compounds that reach the specimens. These findings indicate that devitalized moss transplants cannot be used to monitor either oxidised or reduced N compounds, whereas transplants of metabolically active moss can be used for this purpose. Finally, the NR and PME biomarkers should be used with caution because of the high variability in their activities and the limits of quantification should be evaluated in each case. [ABSTRACT FROM AUTHOR]

Ailanthus altissima (Mill.) Swingle and Robinia pseudoacacia L. are two aggressive invasive trees in riparian areas in Central Spain. We aim to test whether soil properties, nutrient mineralization rates and soil bacterial communities of riparian forest dominated by the native Populus alba L. can be altered by the presence of A. altissima or R. pseudoacacia . In autumn 2011 and spring 2012 we conducted a field soil sampling in three sites where invasive and native trees were paired. In addition, in a 6-month greenhouse experiment (GHE), we grew A. altissima , R. pseudoacacia and P. alba from seeds in a soil collected from a native area. We quantified soil organic matter (OM), nitrogen (N), phosphorous (P), nitrate (NO 3 − –N), ammonium (NH 4 + –N), pH, potential net ammonification and nitrification rates, phosphomonoesterase (PME) activity and the composition of soil bacterial community in soils from the field study and from the GHE. Both the field and the GHE results showed the capability of A. altissima to decrease soil total N and of R. pseudoacacia to increase soil mineral N. In the field, all invaded soils had greater NO 3 − –N than P. alba soils. R. pseudoacacia field soils had greater PME activity, total N and net ammonification rates while A. altissima soils had lower OM, NH 4 + –N, net nitrification and total N mineralization rates than those of P. alba . Differences in the composition of soil bacterial communities were only found in the field, being more evident between A. altissima and P. alba than between R. pseudoacacia and P. alba field soils. Symbiotic N 2 fixation could explain the capability of R. pseudoacacia to increase soil mineral N, while the potential of A. altissima to decrease total soil N may be attributed to changes in the balance between N input and losses from the soil. Although the GHE results indicated that the invasive trees can start changing soil conditions during early stages of establishment, more impacts found in the field study suggests that several soil properties, the composition of soil bacteria communities and microbial activities need longer time since invasion to be altered. [ABSTRACT FROM AUTHOR]

Presented are the data on detection and characterization of phosphomonoesterase and phosphodiesterase activities in detoxicated cultural fluid of production Vibrio cholerae strains 569B and M41, and in choleragen-anatoxin and O-antigenic fraction, the vaccine components. These enzymes were demonstrated to be present in the cholera vaccine tablet, thus its biochemical properties were characterized more completely.