Phosphomonoesterase Activity Research Articles

Quercetin as a Modulator of PTPN22 Phosphomonoesterase Activity: A Biochemical and Computational Evaluation.

Cancer, a group of diseases characterized by uncontrollable cell proliferation and metastasis, remains a global health challenge. This study investigates quercetin, a natural compound found in many fruits and vegetables, for its potential to inhibit the phosphomonoesterase activity of protein tyrosine phosphatase nonreceptor type 22 (PTPN22), a key immune response regulator implicated in cancer and autoimmune diseases. We started by screening seven (7) natural compounds against the activities of PTPN22 in vitro. The initial screening identified quercetin with the highest percentage inhibition (81%) among the screened compounds when compared with ursolic acid that has 84%. After the identification of quercetin, we proceeded by investigating the effect of increasing concentrations of the compound on the activity of PTPN22. In vitro studies showed that quercetin inhibited PTPN22 with an IC50 of 29.59 μM, outperforming the reference standard ursolic acid, which had an IC50 of 37.19 μM. Kinetic studies indicated a non-competitive inhibition by quercetin with a Ki of 550 μM. In silico analysis supported these findings, showing quercetin's better binding affinity (ΔGbind -24.56 kcal/mol) compared to ursolic acid, attributed to its higher reactivity and electron interaction capabilities at PTPN22's binding pocket. Both quercetin and ursolic acid improved the structural stability of PTPN22 during simulations. These results suggest quercetin's potential as an anticancer agent, meriting further research. However, in vivo studies and clinical trials are necessary to fully assess its efficacy and safety, and to better understand its mechanisms of action.

Altitudinal Variation in Soil Acid Phosphomonoesterase Activity in Subalpine Coniferous Forests in China

Studying the altitudinal variation and driving factors of soil acid phosphomonoesterase (ACP) activity in subalpine regions is crucial for understanding nutrient cycling processes within mountainous ecosystems. This study focused on fir (Abies fabri (Mast.) Craib) forests located at three altitudes (2781 m, 3044 m, and 3210 m) on the eastern slope of Mt. Gongga in southwest China. We measured soil ACP activity alongside soil climate, nutrients, and microorganisms at various depths and elevations to investigate how these factors influence ACP activity. The results indicated that in the organic matter horizons (Oe and Oa horizons), ACP activity gradually decreased with elevation. However, the surface mineral horizon (A horizon) did not show a decline in ACP activity with increasing elevation, which could be attributed to significantly lower ACP activity recorded at the 2781 m sample site compared to the 3044 m site. Variance partitioning analysis revealed that among soil climate, nutrients, and microorganisms, soil nutrients had the most substantial impact on ACP activity across all horizons, with a particularly high contribution of 89.4% observed in the A horizon. Random forest model analysis further demonstrated that soil total carbon (TC) played a crucial role in determining ACP activity in the Oe and Oa horizons, with importance values of 8.5% and 7.3%, respectively. Additionally, soil total nitrogen (TN) was identified as the primary factor influencing ACP activity in the A horizon, with an importance value of 12.6%. Furthermore, soil ACP activity was positively regulated by the soil TC:TP and TN:TP ratios, indicating a stoichiometric control of ACP activity in the Abies fabri (Mast.) Craib forests on Mt. Gongga.

Faba bean in crop rotation shapes bacterial and fungal communities and nutrient contents under conventional tillage of triticale

Legumes in cropping sequence can strongly moderate soil biodiversity and its biochemical status, which could influence soil fertility and productivity. However, their impact on soil microbes and their relationships with soil chemical variables during the subsequent crop growth is not understood enough. In this study, we analyzed the changes in bacterial and fungal communities structure through 16S rRNA and ITS amplicon sequencing, respectively, across crop rotation with faba bean (faba bean-wheat-triticale, F) and without faba bean (wheat-wheat-triticale, W). Rhizosphere and bulk soil samples were taken during the triticale growth stages (stem elongation and maturity). Soil enzymatic activity and chemical properties were also determined. Study factors (crop rotation, soil compartment, growth stage) affected N, C, and P transformations, as indicated by the activity of soil enzymes, and F was more beneficial than W for protease, urease, and acid phosphomonoesterase activities, as opposed to cellulase activity. Changes in the chemical properties led to the shift in soil microbial communities with different bacterial and fungal communities' responses. F treatment enhanced the abundance of the bacterial genera representatives such as Streptomyces and Candidatus Udaeobacter while suppressing the abundance of Jatrophihabitans and Terrabacter. Crop rotation significantly influenced fungal genera and a greater abundance of Helgardia, Pseudogymnoascus, Monocillium, Fusarium, Chaetomium, and Vishniacozyma under F than W was noted and the adverse situation was noted for Peziza and Rhizopus. Rotation type significantly affected the alfa-diversity of the fungal, but not bacterial community. Beta-diversity analyses (nMDS, cluster) indicated that the main factor grouping samples were soil compartment and growth stage for the bacterial and fungal microbiome, respectively. The PERMANOVA results revealed significant effects of all factors on bacterial and fungal microbiomes. Different soil chemical variables governed bacterial and fungal communities. Corg, pH, P, Mg, and Corg, pH were the most important soil factors regulating bacterial and fungal community structure by crop rotation, respectively. Bacterial and fungal communities were more related to the content of Ntot in rotation with than without faba bean. The findings of this study contribute to a deeper insight into the relation between the faba bean in cropping sequence and soil microbiome, and modulation crucial soil conditions for the productivity of the successive crop.

Assessment of waterlogging-induced changes in enzymatic antioxidants and carbohydrate metabolism in peanuts genotypes

Soil flooding, manifesting as submergence or waterlogging stress, significantly impacts plant species composition and agricultural productivity, particularly in regions with low rainfall. This study investigates the biochemical responses of two peanut (Arachis hypogaea L.) genotypes, DH-86 and GJG-32, under waterlogging stress. The experiment involved in-vivo pot trials where peanut plants were subjected to continuous waterlogging for 12 days at the flowering stage. Biochemical analyses of leaves conducted and revealed significant alterations in enzyme activities and metabolite concentrations. Key findings include variations in superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPOD), α-amylase, invertase, acid phosphomonoesterase activities, and changes in starch, proline, reducing sugars, and chlorophyll content. SOD, CAT, and GPOD activities exhibited differential responses between genotypes, highlighting DH-86's quicker recovery post-waterlogging. Notably, DH-86 demonstrated higher resilience, reflected in its rapid normalization of biochemical parameters, while GJG-32 showed prolonged stress effects. These findings underscore the importance of antioxidative enzyme systems in mitigating oxidative damage induced by waterlogging. This study enhances our understanding of the biochemical adaptations of peanut genotypes to waterlogging stress, offering valuable insights for breeding programs focused on improving flood tolerance in crops.

Termite mound soil based potting media: a better approach towards sustainable agriculture.

Termite mound soils are known to possess unique physico-chemical and biochemical properties, making them highly fertile. Considering their rich nutrient content, the objective of the current experiment is to assess the physico-chemical properties and enzyme activities of termite mound based potting media and evaluate theirperformance for further exploration in floriculture. Potting media consisting of termite mound soil (TS) of a subterranean termite, Odontotermes obesus were prepared in 7 different combinations with garden soil (GS), sand (S) and farmyard manure (FYM) and a control (without termite mound soil), i.e., T1 (TS, GS, S, FYM (v:v:v:v /1:2:1:1)), T2 (TS, GS, S, FYM (v:v:v:v / 2:1:1:1)), T3 (TS, S, FYM (v:v:v / 2:1:1)), T4 (TS, GS, FYM (v:v:v / 2:1:1)), T5 (TS, GS, S (v:v:v / 2:1:1)), T6 (TS, S, FYM (v:v:v / 3:1:1)), T7 (TS, S, FYM (v:v:v / 1:1:2)) and control (GS, S, FYM (v:v:v / 2:1:1)). The samples were then analysed in laboratory. Experimental analysis on physico-chemical and biological parameters revealed superiority of T7 (TS, S, FYM (v:v:v / 1:1:2)) in terms of pH (7.15), organic carbon (2.13%), available nitrogen (526.02 kg ha-1), available phosphorus (56.60 kg ha-1), available potassium (708.19 kg ha-1), dehydrogenase activity (18.21 μg TTF g-1 soil day-1), Phosphomonoesterase (PME) activity (46.68 54 μg p-nitrophenol/gsoil/h) and urease activity (3.39 μg NH4-N g-1 soil h-1). Whereas T4 (TS, GS, FYM (v:v:v /2:1:1)) registered superiority in terms of PME activity (50.54 μg p-nitrophenol/gsoil/h), Fluorescein diacetate (FDA) activity (11.01 μgfluorescein/gsoil/h) and Soil Microbial Biomass Carbon (SMBC) (262.25 μg/g). Subsequent to the laboratory analysis, two best potting mixtures (T7 & T4) were selected and their performance was assessed by growing a test crop, Tagetes erecta cv. Inca Orange. Considering the growth parameters, the potting media: T7 was found to be significantly superior in terms of plant spread (39.64 cm), leaf area index (4.07), fresh weight (37.72 g), yield (317.81 g/plant), and diameter (9.38 cm) of flower over T4 & control. The Benefit:Cost (B:C) ratio meaning the ratio of net returns to total cost of cultivation was determined. The B:C ratio of raising marigold flower as potted plant in T7 was 1.10 whereas the B:C ratio of the potting mixture of T7 was 2.52. This shows that T7 potting media is also economically viable choice for commercial purposes.

Phosphorus acquisition by faba bean, blue lupin, and chickpea in relation to soil phosphorus status

AbstractThe efficiency of soil phosphorus (P) mobilization and uptake by plants depends on a complex combination of factors, including plant P acquisition strategies and soil P availability. The objective of this study was to assess and compare the capabilities of three legume species (blue lupin (Lupinus angustifolius L.), faba bean (Vicia faba L.), and chickpea (Cicer arietinum L.)), which may be used as green manures in temperate crop systems to acquire P from a soil with different levels of plant‐available P. Three cycles of each legume were grown in a glasshouse over a 6 month period in the same soil type with high (Olsen P: 47 mg kg−1) and low (Olsen P: 9 mg kg−1) levels of plant‐available P. Measurements included above—and below—ground plant biomass and P uptake, in addition to determination of acid and alkaline phosphomonoesterase activities, microbial P, and P fractions in soil at the end of the experiment. In both soils, plant biomass, P uptake, and microbial P were all higher under faba bean compared to blue lupin and chickpea (p < .05). In the low‐P soil, faba bean increased alkaline phosphomonoesterase activity (p < .05). Significant depletion of inorganic P in the soluble (46%–69%), labile (29%–42%), and moderately labile (15%–16%) pools and increase of organic P in the labile (13%–18%) and total (7%–13%) pools occurred under faba bean compared with blue lupin, while changes under chickpea were between those determined for faba bean and blue lupin (p < .05). The findings of this study indicated that inclusion of faba bean green manure may have the potential to improve overall P use efficiency by enhancing mobilization of labile soil inorganic P, although further research is required to investigate mobilization of more stable forms of soil legacy P and quantify the potential of faba bean as a green manure crop under field conditions.

Microbial Biomass and Rhizosphere Soil Properties in Response to Heavy Metal-Contaminated Flooding

Mining and metallurgy are the main sources of soil contamination with harmful metals, posing a significant threat to human health and ecosystems. River floodplains in the vicinity of metal mines or industrial plants are often subject to flooding with sediments containing heavy metals, which can be harmful to the soil ecosystem. This study aimed to investigate the microbial properties of the soil at a metal-contaminated site and to determine the significant relationships between the biological and chemical properties of the soil. The study site was located near the village of Gyöngyösoroszi, in the Mátra mountain region of Northwest Hungary. A phytoremediation experiment was conducted in a metal-polluted floodplain using willow and corn plantations. The soil basal respiration, substrate-induced respiration, soil microbial biomass carbon (MBC), acid phosphatase activities, and soil chemical properties were measured. The soil of the contaminated sites had significantly higher levels of As, Pb, Zn, Cu, Cd, and Ca, whereas the unpolluted sites had significantly higher levels of phosphorus and potassium. The substrate-induced respiration showed a positive correlation with MBC and negative correlations with the metabolic quotient (qCO2). The soil plasticity index and phosphorus showed a positive correlation with MBC, whereas salinity and the presence of Cd, Pb, Zn, As, and Cu showed a negative correlation. Acid phosphomonoesterase activity negatively correlated with the plant-available phosphorus content and MBC, but was positively correlated with the contents of toxic elements, including cadmium, lead, zinc, arsenic, and copper. This study found a significant correlation between the qCO2 and the toxic element content. This suggests that an enhanced metabolic quotient (qCO2), together with a decreased MBC/SOC ratio, could be used to indicate the harmful effect of soil contamination by heavy metals in floodplain soils.

Soil microeukaryotic communities and phosphorus-cycling microorganisms respond to chloropicrin fumigation and azoxystrobin application

Fumigants and fungicides are effective at controlling soil-borne pathogens but might also adversely affect soil beneficial microbes, such as soil phosphorus (P) solubilizing microbes, further altering nutrient cycling processes. Therefore, this study investigated the effects of the fumigant chloropicrin (CP) and the fungicide azoxystrobin (AZO) on soil microeukaryotes and P-cycling related soil bacteria through a greenhouse experiment. Soil microeukaryotic communities and bacterial communities containing two phosphomonoesterase encoding genes (phoC and phoD) were analysed using high-throughput sequencing methods. Results showed that, when applied at the field recommended application dosage, the fungicide AZO had no significant influence on the community structure of soil microeukaryotes and phoD-containing bacteria. However, in CP-fumigated soils, the soil microeukaryotic community composition changed from fungi-dominated to protist-dominated. CP fumigation significantly decreased the total phoC/phoD gene copy number but increased the relative abundance of some phoC/phoD-containing bacteria (such as Sinorhizobium and Streptomyces), which are significantly positively correlated to available P compositions in soil. The structural equation model (SEM) confirmed that CP fumigation could affect soil available P content directly by altering phoC-/phoD-containing bacteria, or indirectly by affecting phoC/phoD gene abundance and acid/alkaline phosphatases activity in soil. The inconsistent changes in phoC/phoD-containing bacteria, phoC/phoD gene number, and the phosphomonoesterase activities indicated that enzyme secretion may not be the only way for P solubilizing soil microorganisms to regulate P availability after soil fumigation. The outcome of this study can provide theoretical support for the design of soil beneficial microorganism recovery strategies and the regulation of phosphate fertilizer after soil fumigation.

Phytin recovered from grain distillation can serve as a phosphorus fertilizer for maize and soybean

AbstractPhosphorus (P) recovery from waste streams can increase food system P use efficiency while simultaneousl mitigating point source P losses. Phytin is a P‐rich waste product generated from maize grain biorefineries, largely located in the US Midwest. However, since the majority of P in phytin is organic, phytin‐P is likely to have limited crop availability in soil following application, as it must first be mineralized to orthophosphate‐P by soil phosphatases. To evaluate the fertilizer potential of phytin recovered from a maize wet milling plant and test hypothesized mechanisms of P mineralization, a five‐step gradient of phytin substitution for monoammonium phosphate (MAP) (0%, 25%, 50%, 75%, and 100% substitution) was evaluated for maize (Zea mays L.) and soybean (Glycine max L.) growth in a P‐deficient Aquic Argiudoll. Irrespective of crop species, aboveground biomass at end of vegetative growth (VT stage) was similar for up to 75% phytin substitution as MAP, but was 21% lower for maize and 49% for soybean when phytin was fully substituted for MAP. Soil microbial biomass carbon (C), nitrogen (N), and P, as well as activities of phosphomonoesterase and phosphodiesterase were invariant across the phytin substitution gradient, suggesting negligible mineralization of phytin P. Full substitution of MAP with phytin lowered soil microbial biomass C:N by 121% for maize and by 153% for soybean, and soil phosphatase activities per unit microbial biomass C were 24% higher under soybean. Our results indicate that phytin can be partially substituted for highly water‐soluble P fertilizers for the two major crop species of the US Midwest in which phytin waste generation is co‐located.

Root phosphatase activity is coordinated with the root conservation gradient across a phosphorus gradient in a lowland tropical forest.

Soil phosphorus (P) is a growth-limiting nutrient in tropical ecosystems, driving diverse P-acquisition strategies among plants. Particularly, mining for inorganic P through phosphomonoesterase (PME) activity is essential, given the substantial proportion of organic P in soils. Yet, the relationship between PME activity and other nutrient-acquisition root traits remains unclear. We measured root PME activity and commonly measured root traits, including root diameter, specific root length (SRL), root tissue density (RTD), and nitrogen concentration ([N]) in 18 co-occurring species across soils with varying P availability to better understand trees response to P supply. Root [N] and RTD were inversely related, and that axis was not clearly related to soil P supply. Both traits, however, correlated positively and negatively with PME activity, which responded strongly to P supply. Conversely, root diameter was inversely related to SRL, but this axis was not related to P supply. This pattern suggests that limiting similarity influenced variation along the diameter-SRL axis, explaining local trait diversity. Meanwhile, variation along the root [N]-RTD axis might best reflect environmental filtering. Overall, P availability indicator traits such as PME activity and root hairs only tended to be associated with these axes, highlighting limitations of these axes in describing convergent adaptations at local sites.

Microbial strategies for phosphorus acquisition in rice paddies under contrasting water regimes: Multiple source tracing by 32P and 33P

Microbial acquisition and utilization of organic and mineral phosphorus (P) sources in paddy soils are strongly dependent on redox environment and remain the key to understand P turnover and allocation for cell compound synthesis. Using double 32/33P labeling, we traced the P from three sources in a P-limited paddy soil: ferric iron-bound phosphate (Fe-P), wheat straw P (Straw-P), and soil P (Soil-P) in microbial biomass P (MBP) and phospholipids (Phospholipid-P) of individual microbial groups depending on water regimes: (i) continuous flooding or (ii) alternate wetting and drying.32/33P labeling combined with phospholipid fatty acid analysis allowed to trace P utilization by functional microbial groups. Microbial P nutrition was mainly covered by Soil-P, whereas microorganisms preferred to take up P from mineralized Straw-P than from Fe-P dissolution. The main Straw-P mobilizing agents were Actinobacteria under alternating wetting and drying and other Gram-positive bacteria under continuous flooding. Actinobacteria and arbuscular mycorrhiza increased P incorporation into cell membranes by 1.4–5.8 times under alternate wetting and drying compared to continuous flooding. The Fe-P contribution to MBP was 4–5 times larger in bulk than in rooted soil because (i) rice roots outcompeted microorganisms for P uptake from Fe-P and (ii) rhizodeposits stimulated microbial activity, e.g. phosphomonoesterase production and Straw-P mineralization. Higher phosphomonoesterase activities during slow soil drying compensated for the decreased reductive dissolution of Fe-P. Concluding, microbial P acquisition strategies depend on (i) Soil-P, especially organic P, availability, (ii) the activity of phosphomonoesterases produced by microorganisms and roots, and (iii) P sources – all of which depend on the redox conditions. Maximizing legacy P utilization in the soil as a function of the water regime is one potential way to reduce competition between roots and microbes for P in rice cultivation.

Contradiction with enzymatic stoichiometry theory: Persistent low ratios of β-glucosidase to phosphomonoesterase following 10-year continuous phosphorus fertilization in three subtropical forests

The ratio of β-glucosidase (BG) to phosphomonoesterase (PME) activity (BG:PME) is often used to predict the intensity of microbial phosphorus (P) shortage, with lower BG:PME indicating stronger P shortage (enzymatic stoichiometry theory). Here, we demonstrated that 10-year continuous P fertilization as high as 150 kg P ha−1 yr−1 in the form of NaH2PO4 solution did not elevate the BG:PME up to the level of other terrestrial ecosystems. The BG:PME of primary, secondary, and planted forests were 0.094, 0.067, and 0.089, respectively in P-fertilized plots, which were much lower than global average (0.62 ± 0.04), despite the fact that Bray-extracted P contents were substantially elevated (more than 600 times). Thus, the findings of the current study suggest that BG:PME overestimates P shortage in our P-enriched forests, implying that the enzymatic stoichiometry theory may not be universally applicable.

Domestication caused taxonomical and functional shifts in the wheat rhizosphere microbiota, and weakened the natural bacterial biocontrol against fungal pathogens

Modern crops might have lost some of their functional traits, required for interacting with beneficial microbes, as a result of the genotypic/phenotypic modifications that occurred during domestication. Here, we studied the bacterial and fungal microbiota in the rhizosphere of two cultivated wheat species (Triticum aestivum and T. durum) and their respective ancestors (Aegilops tauschii and T. dicoccoides), in three experimental fields, by using metabarcoding of 16S rRNA genes and ITS2, coupled with co-occurrence network analysis. Moreover, the abundance of bacterial genes involved in N- and P-cycles was estimated by quantitative PCR, and urease, alkaline phosphatase and phosphomonoesterase activities were assessed by enzymatic tests. The relationships between microbiota and environmental metadata were tested by correlation analysis. The assemblage of core microbiota was affected by both site and plant species. No significant differences in the abundance of potential fungal pathogens between wild and cultivated wheat species were found; however, co-occurrence analysis showed more bacterial–fungal negative correlations in the wild species. Concerning functions, the nitrogen denitrification nirS gene was consistently more abundant in the rhizosphere of A. tauschii than T. aestivum. Urease activity was higher in the rhizosphere of each wild wheat species in at least two of the research locations. Several microbiota members, including potentially beneficial taxa such as Lysobacter and new taxa such as Blastocatellaceae, were found to be strongly correlated to rhizospheric soil metadata. Our results showed that a functional microbiome shift occurred as a result of wheat domestication. Notably, these changes also included the reduction of the natural biocontrol potential of rhizosphere-associated bacteria against pathogenic fungi, suggesting that domestication disrupted the equilibrium of plant-microbe relationships that had been established during million years of co-evolution.

Selective logging impacts on soil microbial communities and functioning in Bornean tropical forest.

Rainforests provide vital ecosystem services that are underpinned by plant-soil interactions. The forests of Borneo are globally important reservoirs of biodiversity and carbon, but a significant proportion of the forest that remains after large-scale agricultural conversion has been extensively modified due to timber harvest. We have limited understanding of how selective logging affects ecosystem functions including biogeochemical cycles driven by soil microbes. In this study, we sampled soil from logging gaps and co-located intact lowland dipterocarp rainforest in Borneo. We characterised soil bacterial and fungal communities and physicochemical properties and determined soil functioning in terms of enzyme activity, nutrient supply rates, and microbial heterotrophic respiration. Soil microbial biomass, alpha diversity, and most soil properties and functions were resistant to logging. However, we found logging significantly shifted soil bacterial and fungal community composition, reduced the abundance of ectomycorrhizal fungi, increased the abundance of arbuscular mycorrhizal fungi, and reduced soil inorganic phosphorous concentration and nitrate supply rate, suggesting some downregulation of nutrient cycling. Within gaps, canopy openness was negatively related to ectomycorrhizal abundance and phosphomonoesterase activity and positively related to ammonium supply rate, suggesting control on soil phosphorus and nitrogen cycles via functional shifts in fungal communities. We found some evidence for reduced soil heterotrophic respiration with greater logging disturbance. Overall, our results demonstrate that while many soil microbial community attributes, soil properties, and functions may be resistant to selective logging, logging can significantly impact the composition and abundance of key soil microbial groups linked to the regulation of vital nutrient and carbon cycles in tropical forests.

No differences in phosphodiester-induced changes of phosphatase activities and bicarbonate-extractable inorganic phosphorus between long-term low and high phosphorus-fertilized soils

Soil organic phosphorus (P) mineralization is catalyzed by phosphatases synthesized by plants or microorganisms, particularly when organic P is present and inorganic P is limited. We investigated how P status affects the substrate induction response of phosphatase activities and changes in labile inorganic P (ΔNaHCO3-Pi) by adding phosphodiester to long-term low P and high P-fertilized soils. Phosphodiester addition significantly increased acid phosphomonoesterase activity and ΔNaHCO3-Pi, while exhibiting non-significant effect on phosphodiesterase activity. No significant differences were observed in phosphodiester-induced phosphatase activities and ΔNaHCO3-Pi between the low P and high P-fertilized soils. Our results indicate that phosphodiester may incentivize microbially mediated enzymatic P mineralization not necessarily for P but possibly for energy. This emphasizes the importance of phosphodiester in the development of microbial strategies for mobilizing soil P.

Soil enzyme activities in heavily manured and waterlogged soil cultivated with ryegrass (Lolium multiflorum)

Extended waterlogging (WL) conditions can alter soil enzyme activities and their role in maintaining healthy soils. We assessed the effects of soil moisture regimes (field capacity [FC] and WL) and phosphorus (P) rates (0, 15, 30, 45 kg available P ha–1) on ( i) soil enzymes and microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial biomass P (MBP); and ( ii) dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). The treatments were tested in a 4-month greenhouse experiment using intact soil columns under annual ryegrass ( Lolium multiflorum). WL decreased the activity of β-glucosidase and acid phosphomonoesterase but increased N-acetyl-β-glucosaminidase in soils. These changes were associated with changes in MBC, DOC, MBN, and TDN, but not MBP. Anoxic conditions in WL soil promote the activity of anaerobes and contribute to the reduction of Fe oxyhydroxides and the release of DOC, TDN, and P in the soil solution. The activity of the extracellular enzymes decreased in WL with additions of slurry indicating adequate supply of C, N, and P. Our results also showed that both enzyme activities and microbial biomass were restricted in the upper soil layer with limited downward movement along the soil profile. We can conclude that since these enzymes control the hydrolysis of cellulose, phosphomonoester, and chitin, soil moisture influences the direction and magnitude of C, N, and P in manured and waterlogged soil cultivated with ryegrass.

Effects of Adding Native Annual Seeds to South Korea Native Perennial Seed Mixture on Early Stage Vegetation Recovery, Soil Enzymes, and Nutrient Dynamics in Post-Fire Soils

Forests are degraded from various factors, and the first step in restoration frequently involves revegetation. One of the degradations is wildfires, which damage vegetation, affect soils, and lead to the loss of ecosystem functions. Using seed mixtures is a viable method for restoring the ecosystems. This research investigated the impacts of six perennial plant seed mixtures derived from native plants in South Korea and the addition of two types of annual plant seeds to these mixtures, both separately and combined. Cultivation of the seed mixtures was conducted by pot cultivation in a greenhouse for the early stage of vegetation (16 weeks). The seed mixture treatment enhanced plant species diversity, number, and biomass. The seed mixture treatment elevated the urease activity from 14.42 to values between 33.88 and 55.74 μg NH4-N g−1 2 h−1. A seed mixture integrated with two annual plants heightened the phosphomonoesterase activity from 482.79 to 543.75 μg p-nitrophenol g−1 h−1. Nitrogen leaching was reduced across all seed mixture treatments, while phosphorus leaching diminished with the addition of the annual legume. These findings illustrate the influence of seed mixture treatments and the inclusion of annual seeds on the beginning stage of revegetation, offering a basis for further ecosystem restoration.

Long-term organic fertilization reshapes the communities of bacteria and fungi and enhances the activities of C- and P-cycling enzymes in calcareous alluvial soil

Soil microbial communities and extracellular enzymes are pivotal in governing the dynamics of soil carbon (C) and phosphorus (P) cycling. Nevertheless, comprehending the underlying regulatory factors and intricate interactions among these vital indicators remains an inadequately explored aspect, especially within the scenario of long-term fertilization. Long-term fertilization experiments were conducted on calcareous alluvial soil. The five fertilization regimes selected were as follows: without fertilization treatment (CK); inorganic NK fertilization treatment (NK); inorganic NPK fertilization treatment (NPK); organic fertilization treatment (M); and combined inorganic NPK with organic fertilization treatment (NPKM). The soil physicochemical properties, β-glucosidase (BG), and alkaline phosphomonoesterase (ALP) activities were determined, together with microbial (bacterial and fungal) community DNA sequences and subsequent bioinformatics analysis after 38 years of different fertilization. The results showed that the content of soil organic carbon (SOC) and available P and the activities of BG and ALP were the highest after M and NPKM treatments, which were 79–104 %, 26–36 times, 161–171 %, and 75–91 % higher than CK, respectively. Hierarchical clustering analysis showed that the bacterial and fungal community structures in M and NPKM treatments were similar, but the community structures in non-organic fertilization treatments (CK, NK, and NPK) were significantly different from those in organic fertilization treatments. The indicator species and correlation analysis combined revealed that most indicator species in organic fertilizer treatments were significantly positively correlated with soil BG and ALP, while most indicator species in non-organic fertilizer (CK and NK) treatments were significantly negatively correlated with soil BG and ALP. Organic fertilization treatments favored the growth of the bacterial genus Lysobacter and the fungal genera Acremonium and Mortierella and were significantly positively correlated with BG and ALP activities. Redundancy analysis revealed that SOC is the most important factor in shaping microbial community structure. Co-occurrence network analysis showed organic fertilization had higher network complexity, more keystone taxa, and more associations among microbial taxa compared with non-organic fertilization (CK + NK). Structural equation models revealed that microbial community structure is the direct driving factor of BG and ALP activities and their interactions, and SOC modulated the relationship between microbial community structure and BG and ALP activities. This study highlights how the application of organic fertilizer enhanced the C- and P-cycling enzyme activities, reshaped the soil microbial communities, and regulated these crucial indicators and their interactions by SOC.

Land reclamation increased organic P fractions and phosphatase activities, and strengthened the co-occurrence networks of phoD community in calcareous soils

Organic phosphorus (Po) is an important constituent of P pool. Soil phoD community is primarily involved Po transformation. However, influences of agriculturally-driven land-use change on different Po fractions, phosphatase activities and phoD community are largely unknown. Here, an investigation was carried out containing three treatments: vegetable field (VF), cropland (CF) and uncultivated land (UL). Various Po fractions were measured by Hedley’s sequential extraction and 31P-NMR methods. The activities of alkaline phosphomonoesterase (ALP), acid phosphomonoesterase (ACP), phosphodiesterase activity (PD) and phytase were assayed; the abundance, and diversity of phoD community and its co-occurrence networks were analyzed. Compared with the UL treatment, soil total organic P (total-Po) in the VF and CF treatments significantly increased by 75.9% and 53.0%, respectively, mainly attributed to the increases in NaHCO3-Po, NaOH-Po and C.HCl-Po. 31P-NMR spectra showed that, when land was reclaimed from uncultivated land into agriculture fields (i.e., VF and CF), myo-inositol hexaphosphate (myo-IHP), α-glycerophosphate (α-glyc) and β-glycerophosphate (β-glyc) were increased by 9.5, 3.9 and 2.0 times, respectively. The activities of ACP, ALP and PD in the VF and CF treatments were higher than in the UL treatment. The α-diversity of phoD community was also significantly increased by land reclamation. Moreover, the linkage between soil Po and Po-cycling-related biological parameters (ACP, ALP and PD and phoD community) was more pronounced by NaHCO3-Po and NaOH-Po than the Po fractions measured by 31P-NMR method. Topological parameters (edges, node degree, and betweenness centrality) of phoD community’s network in the VF and CF networks were higher than in the UL network, implying that land reclamation favored to construct a more cooperative network of phoD community. Collectively, our findings demonstrated that when uncultivated land was converted to cropland, soil Po was notably increased, and phoD community’s co-occurrence network was also strengthened. The outcomes of this study emphasize that when land was reclaimed from nature (uncultivated land) into agriculture fields, the fertilization strategy of organic combined with chemical fertilizers application was beneficial for improving P fertility and assembling organic P-cycling related community.

Long-term nitrogen fertilization and sweetpotato cultivation in the wheat-sweetpotato rotation system decrease alkaline phosphomonoesterase activity by regulating soil phoD-harboring bacteria communities

The alkaline phosphomonoesterase (ALP)-harboring community (phoD-harboring community) plays a crucial role in the conversion of organic phosphorus (P) into available P (AP). However, the response mechanisms of phoD-harboring communities to fertilization strategies, crop types, and their interactions within the wheat-sweetpotato rotation are poorly understood. A nine-year field experiment of different fertilization strategies was established under the wheat-sweetpotato rotation. After harvesting the crop, we collected soil samples without fertilization (CK), inorganic NK fertilization (NK), inorganic NPK fertilization (NPK), and a combined application of inorganic NPK and organic fertilizer (NPKM). We employed high-throughput sequencing and enzymology techniques to analyze the composition and functional activity of phoD-harboring bacterial communities as well as their correlation with soil physicochemical properties. The results showed that long-term nitrogen (N) fertilization, especially inorganic N, significantly reduced soil pH and ALP activity while increasing AP compared with CK. The AP content in sweetpotato season was significantly higher than that in wheat season. Inorganic N fertilization dramatically reshaped the communities of phoD-harboring bacteria and decreased diversity. The phoD-harboring bacterial communities in sweetpotato season were significantly different from those in wheat season. The N fertilization significantly reduced the relative abundance of Acuticoccus, Methylibium, Rhizobacter, and Roseivivax, which was positively correlated with ALP activity. These groups in sweetpotato season decreased significantly compared with wheat season. A structural equation model indicates that pH and AP play a significant role in regulating the phoD-harboring bacteria communities, ALP activity, and their interactions. We demonstrate that fertilization strategies and crop types have a substantial impact on the phoD-harboring bacteria communities and functions, which are closely linked to soil pH and AP levels. Our study highlights the detrimental effects of soil acidification resulting from inorganic N fertilization on P-cycling bacterial communities and functions. However, the combination of inorganic and organic fertilizer can mitigate these adverse effects.