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1.
This study determined the cell density in the field and the biological activity of culturable phosphate-solubilizing microorganisms (PSMs) present in the Elaeis guineensis Jacq. rhizosphere at two locations in a commercial plantation. Promising isolates found in two soils under different agronomic management conditions were selected. We first calculated the cell density of cultivable PSMs grown in SRS medium (Sundara-Rao and Sinha, 1963) supplemented with the insoluble phosphate sources Ca3(PO4)2, AlPO4, and FePO4. Twenty-two bacteria, ten filamentous fungi, and eight yeast isolates were found. The 16 isolates with the clearest P solubilization halo in Petri dishes were selected to estimate their P solubilization potential in SRS medium with Ca3(PO4)2. No solubilization activity was registered using AlPO4 or FePO4 as the P sources. Ten of the isolates presented solubilization efficiencies between 20 and 82%. Some of these isolates showed high percentages of identity with the 16S and ITS rDNA sequences of the genera Aspergillus, Penicillium, Klebsiella, Burkholderia, and Staphylococcus according to the NCBI and EzTaxon-e databases. The solubilization activity of the isolates was associated with a decrease in the pH and the release of organic acids, such as gluconic, citric, succinic, and acetic acids. Gluconic acid was mainly released by the genera Aspergillus and Penicillium, and these isolates also showed the highest solubilization activities (82 and 80%, respectively). Therefore, these isolates were selected as the most promising isolates present in the oil palm rhizosphere for phosphate solubilization.  相似文献   

2.
几株高效溶磷菌株对不同磷源溶磷活力的比较   总被引：3，自引：0，他引：3  
在液体培养条件下，研究了4株溶磷菌株(Bmp5、Bmp6、Bmp7和Fmp9)对不同磷源溶解能力的差异并与荧光假单孢菌As1.867和巨大芽孢杆菌As1.223进行了比较，探讨了菌株组合培养对溶磷活力的影响。结果表明，4株菌株对磷酸钙、磷酸铝、磷酸氢钙溶解能力明显高于磷酸铁和卵磷脂。以磷酸钙为磷源时，Fmp9的溶磷量比As1.867和As1.223分别高出约92%和48%；而以磷酸铝为磷源时，As1.223的溶磷量明显高于其他菌株；在磷酸氢钙为磷源的条件下，Bmp6为优势菌株，溶磷量高达785.51mg/L。对比研究发现，Bmp5、Bmp6、Bmp7及Fmp9的优势磷源分别为卵磷脂、磷酸氢钙、磷酸铝和磷酸钙。组合培养表明，Bmp5+Fmp9和Bmp6+Fmp9较单株菌的溶磷量有所增加，为较好的组合。试验得到的溶磷微生物配方已经应用于生物复合肥料的研究，并进行了盆栽实验，得到了较好的效果。该研究可为土壤生物肥料工业的微生物学研究提供借鉴。  相似文献   

3.
Many soil microorganisms are able to transform insoluble forms of phosphorus to an accessible soluble form, contributing to plant nutrition as plant growth-promoting microorganisms (PGPM). The objective of this work was to isolate, screen and evaluate the phosphate solubilization activity of microorganisms in maize rhizosphere soil to manage soil microbial communities and to select potential microbial inoculants. Forty-five of the best isolates from 371 colonies were isolated from rhizosphere soil of maize grown in an oxisol of the Cerrado Biome with P deficiency. These microorganisms were selected based on the solubilization efficiency of inorganic and organic phosphate sources in a modified Pikovskaya's liquid medium culture containing sodium phytate (phytic acid), soybean lecithin, aluminum phosphate (AlPO4), and tricalcium phosphate (Ca3(PO4)2). The isolates were identified based on nucleotide sequence data from the 16S ribosomal DNA (rDNA) for bacteria and actinobacteria and internal transcribed spacer (ITS) rDNA for fungi. Bacteria produced the greatest solubilization in medium containing tricalcium phosphate. Strains B17 and B5, identified as Bacillus sp. and Burkholderia sp., respectively, were the most effective, mobilizing 67% and 58.5% of the total P (Ca3(PO4)2) after 10 days, and were isolated from the rhizosphere of the P efficient L3 maize genotype, under P stress. The fungal population was the most effective in solubilizing P sources of aluminum, phytate, and lecithin. A greater diversity of P-solubilizing microorganisms was observed in the rhizosphere of the P efficient maize genotypes suggesting that the P efficiency in these cultivars may be related to the potential to enhance microbial interactions of P-solubilizing microorganisms.  相似文献   

4.
To confirm whether endophytes are members that play important roles in phosphorus (P) solubilization in red acidic soil, five endophytes that have the potential to dissolve insoluble P were isolated from cassava (Manihot esculenta Crantz) root. Based on the maximum amount of soluble P in Ca3(PO4)2, AlPO4, and FePO4 liquid NBRIP, the strain Pantoea dispersa was selected to investigate the ability to solubilize phosphate over time. Our results showed that the solubilizing process of P. dispersa was accompanied by acid production. Beside succinate, oxalic acid, and citric acid, two special organic acids, salicylic acid, and benzeneacetic acid were found during microbial P solubilization. Based on PCR-DGGE (denaturing gradient gel electrophoresis) analysis, soil application of P. dispersa triggered natural soil microbial activity. This phenomenon could be maintained up to 25 days, suggesting that the endophyte P. dispersa would be a suitable candidate for optimizing agro-microecological systems via soluble P release in red acidic soil.  相似文献   

5.
A laboratory experiment was conducted to evaluate the P mobilization potentials of six bacterial strains isolated from three wheat-growing soils of Australia. Four different forms of insoluble phosphorus (P) were used in this experiment. Two strains (Pantoea ananatis and Pantoea sp.) mobilized more P from calcium phosphate [Ca3(PO4)2] when ammonium sulfate [(NH4)2SO4] was used as a source of nitrogen (N) compared to ammonium nitrate (NH4NO3) as the N source. The remaining four strains showed increased P-mobilizing ability with nitrate as sources of N. Cultures containing Burkholderia sp. showed a greater net increase in soluble P from rock phosphate compared to Ca3(PO4)2. Mobilization of P from aluminium phosphate (AlPO4) and iron phosphate (FePO4) was much lower than from calcium P sources in cultures containing all the bacterial strains tested. Pantoea ananatis and Pantoea sp. were significantly better than other strains in mobilizing P from AlPO4 whereas Pantoea sp. was identified as a minor P mobilizer from FePO4.  相似文献   

6.
黎耀辉 《土壤学报》1964,12(1):78-82
在前一报告中[1],作者通过室内化学分析及生物试验证明,在所试的六种测定土壤有效磷的方法中,以Olsen的0.5M NaHCO3法与生物反应的相关性最好,马乞金的1%(NH4)2CO3法和Radet的3.5%柠檬酸钠法次之,Egner-Rim的乳酸钙法、Burriel-Hern-ando的混合浸提液法和Joret-Herbert的草酸铵法又次之。另外,从浸提出的磷量看,碳酸氢钠法、马乞金法和柠檬酸纳法相当接近,可以列为同一数量级。乳酸钙法、混合浸提液法和草酸铵法浸出的磷量也很接近,可以列为另一较高的数量级。  相似文献   

7.
Almost 900 fungal isolates were obtained from eight coffee plantations in Colombia and Mexico. Of these, 76 isolates showed activity to solubilize Ca3(PO4)2 (PCa) and FePO4·H2O (PFe), which had been added to agar in a plate test. Generally, PCa was better solubilized than PFe. Colombian isolates were generally somewhat less effective than Mexican isolates. The two most effective isolates from each country with apparent highest PFe, solubilization potential were selected and cultivated in liquid medium containing PFe, which is more prevalent in tropical soils. The pH value, solubilized P in the medium and P uptake in fungal biomass were determined. After 24 days, Cylindrocarpon didymum and C. obtusisporum (both from Colombia) had solubilized 9.9 and 6.4 mg PO4 3--P L?1 and took up 8.6 and 11.6 mg P in biomass. Penicillium janthinellum and Paecilomyces marquandii (both from Mexico) solubilized 7.0 and 1.9 mg PO4 3--P L?1 and took up 11.3 and 17.3 mg P in biomass. The potential practical use of the four fungal isolates for different strategies in making more P available for coffee growth is discussed.  相似文献   

8.
Common sequential phosphorus (P) extraction methods are not specific to particular chemical species and have several limitations. This work presents the first chemical method for quantification of individual mineral and sorbed P species. It was developed by combining a conversion technique with a sequential extraction procedure. Mangrove sediments with different characteristics were incubated in pH‐adjusted 0.01 M CaCl2 with and without reference material additions of octacalcium phosphate (Ca8H2(PO4)6·5H2O; OCP), hydroxyapatite (Ca5(PO4)3OH), strengite (FePO4·2H2O) or variscite (AlPO4·2H2O). The changes in soluble phosphate concentration were measured in the supernatant solution, while pH‐induced variations in P composition were determined by subsequent sequential extraction of the sediments. Dissolved phosphate concentration was controlled by adsorption below pH 7.8. Above this pH, soluble phosphate concentration was governed by OCP, which was qualitatively determined by plotting the experimental values of pH + pH2PO4 and pH – 0.5 pCa on a solubility diagram including the isotherms of known crystalline phosphate compounds. In contrast to the often‐predicted slow dissolution rate of crystalline phosphates in soils or sediments, drastic changes in P composition by dissolution, precipitation and adsorption processes were detected after 7 days. These were mainly not observed indirectly by changes in dissolved phosphate through adsorption effects, but were determined quantitatively by subsequent sequential extraction, thus enabling the quantification of individual species. Evaluation of the method was performed by standard addition experiments. Besides P species quantification, the method provides the means for other applications, such as the determination of P mineral dissolution kinetics in soils and sediments, the prediction of P composition in changing environmental settings and the refinement of theoretical models of phosphate solubility in soil and sedimentary environments.  相似文献   

9.
A way to bring phosphate-saturated soils back to an environmentally safe P level is by P mining through plants. Phosphate-solubilizing bacteria (PSB) could be very useful for increasing mining efficiency over time. The goal of this research was to investigate the adaptation and performance of PSB in conditions of high total P content in soil. In the first experiment, the P-solubilizing capacity of five PSB species (three Bacillus spp. and two Pseudomonas spp.) were tested under fully controlled conditions on several growth media with different forms of insoluble phosphate (FePO4, AlPO4, or (Ca)3(PO4)2) added at different rates. The colony growth after 14 days of inoculation demonstrated that all five bacteria were able to proliferate and solubilize P on each of the tested growth media, in contradiction with the normally used technique of halo determination. In the second experiment, the same bacterial species were inoculated in pure quartz sand amended with a nutrient solution and P was added separately in an insoluble form, as Fe–P, Al–P, or Ca–P. The extractable ammonium lactate ranged from 3.2 to 6.9 and 29.0 to 40.7 mg?kg?1 sand for the insoluble Al–P and Fe–P treatments, respectively. Pseudomonas putida and Bacillus brevis performed best as PSB at high P concentration where the P is fixed with Al or Fe. In the third experiment, P. putida and B. brevis were inoculated in an acidic sandy, P-saturated soil for 4 weeks. The inoculation of the PSB gave promising results in solubilizing P.  相似文献   

10.
磷胁迫条件下油菜、肥田萝卜对难溶性磷的活化与利用   总被引：1，自引：2，他引：1  
通过砂培试验研究了北方食用油菜和南方绿肥作物肥田萝卜两种植物在缺磷胁迫条件下对难溶性磷酸盐Ca3(PO4)2和AlPO4的活化利用情况。试验结果表明,在仅供应一种难浴性磷酸盐时,油菜和肥田萝卜对磷酸铝和磷酸三钙都有较大程度的活化与利用。在施用AlPO4时肥田萝卜地上部吸磷量达到供应等磷量水溶性磷酸盐时的90％;在施用Ca2(PO4)2时油菜地上部吸磷量达到供应等磷量水溶性磷酸盐时的49％。植物干物重的测定结果说明,在缺磷时,难溶性的Ca3(PO4)2及AlPO4对油菜和肥田萝卜均有促进生长的作用。但是,油菜与肥田萝卜对Ca3(PO4)2和AlPO4的活化利用程度却存在着一定差异。表现为油菜对Ca3(PO4)2的利用能力强,而肥田萝卜对AlPO4的利用能力强。  相似文献   

11.

Purpose

The combined contamination of Pb, Zn, Cu, Cd, and As in the soils near lead/zinc mine waste posed a potential threat to the surrounding environment. Mitigation methods are needed to reduce the environmental risk. The aims of this paper were to evaluate the feasibility and efficiency of different forms of phosphates in remediating combined contamination caused by multi-metals and arsenic near the lead/zinc mining tailings.

Materials and methods

The tested soil was taken from a clayey illitic thermic typic epiaquepts soil (depth of 0–20 cm) near a lead and zinc mine tailing, located in Shaoxing, Zhejiang Province, China. Four pure chemical reagents, K2HPO4, Ca(H2PO4)2.2H2O, Ca3(PO4)2, and Ca5(PO4)3OH, were added to the soil in solution form as the trace metal stabilizing additives at a P application rate equivalent to 2,283 mg P/kg-soil and P/Pb molar ratio of 1. Shifts in trace metal speciation were determined using sequential extraction procedures and relative toxicities were evaluated using the standard EPA toxicity characteristic leaching procedure (TCLP).

Results and discussion

The addition of K2HPO4, Ca3(PO4)2, Ca5(PO4)3OH, and Ca(H2PO4)2.2H2O in the contaminated soil at the phosphorus application rate 2,283 mg P/kg-soil reduced Pb concentrations in TCLP extraction solution from 90.47 to 56.05, 83.80, 67.78, and 86.32 mg/kg (38.0, 7.36, 25.1, and 4.59% reduction), respectively. Sequential extraction analysis showed that phosphate treatments caused the transformation of easily available trace metal species to more stable forms. However, TCLP As in the soil increased from its initial value of 0.23 to 2.1, 0.70, 0.67, and 0.77 mg/kg, respectively, for the four treatments. The TCLP leachable As concentration of the K2HPO4-treated soil was about nine times of that from the untreated soil.

Conclusions

The addition of K2HPO4, Ca3(PO4)2, Ca5(PO4)3OH, and Ca(H2PO4)2.2H2O were effective in reducing water soluble and exchangeable Pb, Zn, Cu, and Cd, and minimizing TCLP-extractable Pb, Zn, and Cu. The sequential extraction test and the TCLP indicate that Ca5(PO4)3OH treatment has a higher potential in immobilizing Pb, Zn, Cu, and Cd, though a slight enhancement of As mobility, comparing with other phosphate treatments.  相似文献   

12.
Phosphorus (P) mobilizing bacteria play an important role in the availability of soil and fertilizer P for all crops including wheat. Two greenhouse experiments were conducted to evaluate the effects of six P mobilizing bacterial strains and three P sources tricalcium phosphate {[Ca3(PO4)2], calcium hydrogen phosphate [CaHPO4.2H2O] and rock phosphate} on yield and P uptake of wheat. All the bacterial inoculants increased grain yield significantly over control in one greenhouse experiment while only three strains produced significantly higher grain yield over control in a second experiment. Difference among P sources were not significant in acquiring grain yield in experiment 1 while Ca3(PO4)2 and CaHPO4.2H2O produced significantly higher grain yield over rock phosphate in experiment 2. The differential pattern in results in two experiments might be due to difference in growth conditions. More greenhouse studies as well field experiments are recommended to confirm the beneficial effects of these P mobilizing bacterial strains on wheat.  相似文献   

13.
Phosphorus availability is a major limiting factor for yield of most crop species. The objective of this study was to compare the solubilization of three sources of phosphorus (P) by different fungal isolates and to determine the possible mechanisms involved in the process. Talaromyces flavus (S73), T. flavus var flavus (TM), Talaromyces helicus (L7b) and T. helicus (N24), Penicillium janthinellum (PJ), and Penicillium purpurogenum (POP), fungal strains isolated from the rhizosphere of crops, are known to be biocontrol agents against pathogenic fungi. The P solubilization efficiency of these fungal strains in liquid media supplemented either with tricalcium phosphate (Ca3(PO4)2; PC), aluminum phosphate (AlPO4; AP), or phosphorite (PP) depended on the source of P and the fungal species. The type and concentration of organic acids produced by each species varied according to the source of available P. In the medium supplemented with PC, the highest proportion was that of gluconic acid, whereas in the media supplemented with the other P sources, the highest proportion was that of citric and valeric acids. This suggests that the release of these organic compounds in the rhizosphere by these microorganisms may be important in the solubilization of various inorganic P compounds. Results also support the hypothesis that the simultaneous production of different organic acids by fungi may enhance their potential for solubilizing insoluble phosphate.  相似文献   

14.
Abstract

Several phosphate solubility and availability parameters were obtained for calcareous soil samples fertilized with superphosphate, partially acidulated phosphate rock and a mixture of the two. Plant response to the fertilizer application was studied in a greenhouse experiment. The ionic product of calcium carbonate phosphate [Ca3(HCO3)3PO4] correlated best with the plant response parameters. The correlations of the plant response parameters with the other solubility parameters (CaPO4, H2PO4 or HPO4 potentials) were higher than that obtained with conventionally determined available soil phosphorus (P).  相似文献   

15.
Phosphate-solubilizing microorganisms play an important role in plant nutrition by enhancing phosphorus (P) availability to roots through converting the insoluble phosphates into soluble ions. We isolated phosphate-solubilizing bacteria (PSB) from acidic soil (Ultisols) in the field from the layer of 0–150 mm at a tea garden located at 28°38′26″ N and 116°24′27″ E. The capacity of bacterial isolates to solubilize mineral phosphate was tested on aluminum phosphate (AlPO4) in liquid medium. Among these PSB, isolate B1 (identified as Bacillus thuringiensis) exhibited the maximum P-solubilizing ability and was particularly efficient at solubilizing AlPO4 (up to 321 mg L?1) in vitro. The isolate B1 was inoculated to an acidic soil to study its effect on phosphate solubilization and growth of peanuts (Arachis hypogeae). The Olsen-P in the tested soil increased from 14.7 to 23.4 mg kg?1, with solubilization of 16.4 mg kg?1 soil of Occluded-P after 14-day incubation. The inoculation by B1 significantly increased plant height (from 37.7 to 45.7 cm), number of branches (from 34.0 to 52.7 per plant), hundred-seed weight (from 42.1 to 46.9 g) and crude protein content (from 243.5 to 268.2 g kg?1 dry weight). The phosphate-solubilizing B. thuringiensis strain B1 showed potential as a biological phosphorus fertilizer.  相似文献   

16.
The extent to which soil phosphorus (P) status affected the incidence of soil phosphate-solubilising bacteria (PSB) and their taxonomic abundance and diversity was examined at three long-term fertiliser trials (Whatawhata, Winchmore and Ballantrae) in New Zealand. Bacteria were isolated from rhizosphere (ryegrass and clover) and non-rhizosphere soils differing in P status. The P-solubilising phenotype was determined on agar supplemented with sparingly-soluble mineral phosphates (Ca2OH(PO4)3 and CaHPO4). The frequency of P-solubilisation in the bacterial population was significantly greater (P < 0.001) in soils of low-P status, demonstrating a selection pressure for this trait based on soil P availability. P-solubilising bacteria from high-P level soils and soils which had not received P fertiliser (nil-P soils) were identified based on 16S rRNA-gene sequence analysis. Across the samples, the P-solubilising community was very rich with 39 genera of PSB found, spanning 24 families and 4 phyla. At Ballantrae and Winchmore, the PSB composition differed (P < 0.05) across soil P status, which was associated with an alteration in abundance of Actinobacteria, Pseudomonadaceae and Moraxellaceae. The phylogenetic composition of PSB differed significantly (P < 0.05) between sites, however nearly half the families were common across all sites, constituting a ‘core community’ of P-solubilising bacteria for these New Zealand pasture soils. As the abundance and composition of P-solubilising bacteria are under strong selection pressure affected through farm management strategies, better understanding of their ecology provides the opportunity to increase the availability of soil P for plant-uptake.  相似文献   

17.
The immobilization of lead by the reaction with phosphate bearing materials is a promising remediation method for contaminated soils. Low soluble neo-formed lead-phosphate phases similar to chloropyromorphite [Pb5(PO4)3Cl], can control availability and mobility of lead in the environment, and consequently reduce human exposure, if soils are the main contamination pathway. We used three phosphate source materials [NaH2(PO4)3, commercial superphosphate and phosphate rock] to study lead immobilization in soil and mining waste samples. Products were examined after 1, 3 and 6 months of contact. The samples are from a contaminated area by former Pb mining and smelting activities, in southeastern Brazil, where epidemiological studies showed high lead blood levels in local population. The PBET (physiological based extraction test) bioaccessibility test was used to measure changes in the amount of soluble lead after sample treatment. Results show that the most efficient phosphate source was NaH2(PO4)3, which reduced lead solubility to 92% in acidic gastric conditions after the first month of contact. Superphosphate and phosphate rock also diminished Pb solubility, but the effect was more time dependent. None specific Pb–phosphate phases could be identified by XRD in whole treated samples, but the Pb–Ca–P elemental associations, observed on SEM images and EDS spectra of portions of the samples, combined with the reduced solubility, indicate that more insoluble lead phases were formed after the treatment. Based in these results, the in site phosphate application on soils to induce lead immobilization should be considered as a possible alternative to reduce human exposure at the area.  相似文献   

18.
Sorption isotherms and calcium phosphate solubility data were used to interpret the processes responsible for sorption of phosphate on three Jurassic oolitic limestones whose surface areas ranged from 1.0 to 1.5 m2/g CaCO3. It was concluded that total sorption was due to (1) an initial chemisorption reaction at final P concentrations below 0.5 μg/ml, with Langmuir adsorption parameters of about k = 10 ml/μg P and xm = 100 μg P/g; above this concentration most of the additional sorption was due to (2) phisical adsorption (of very low bonding energy) which may occur in multilayers on the initial chemisorbed layer, and (3) precipitation, probably of octacalcium phosphate, Ca8H2(PO4)6.5H2O, from solution and its deposition on the adsorbed layers. The last two reactions probably overlap and cannot be distinguished from each other.  相似文献   

19.
Desert soils are infertile, and the ability to improve them by P-fertilization is limited by the solubility of phosphate. We aimed to understand the function of phosphate solubilizing bacteria and the mechanisms behind phosphate solubilization in desert soils. Vegetated and barren desert soils, mine spoil and a fertile temperate grassland loam were sampled. Bacteria and fungi were isolated and identified, and their phosphate-solubilizing abilities were measured in vitro. The release of plant available PO4, SO4, NO3 and NH4 from desert soils did not compare with that of a grassland soil. Desert soils had substantially lower solubilization than grassland, 162 and 99–121 µg PO4-P g?1 dry soil, respectively. Phosphate-solubilizing bacteria and fungi were inhabiting the soils. Si addition increased phosphate solubilization of fungi by 50%. The isolated microbes were shown, using 31P nuclear magnetic resonance (NMR) analysis, to rapidly take-up both intracellular and extracellular phosphate during the phosphate solubilizing process. Desert soil had potentially active microbial populations that are capable to solubilize inorganic phosphorus; S and Si as the limiting factors. Acidification as the main mechanism to solubilize mineral phosphate was not as evident in our desert soils as in former studies dealing more fertile soils.  相似文献   

20.
Ericoid mycorrhizal fungi increase the ability of their host plants to colonize soils polluted with toxic metals, although the underlying mechanisms are not clearly understood. Two mycorrhizal strains of Oidiodendron maius isolated from contaminated soil were previously shown to tolerate high concentrations of toxic metals. We investigated further the biological mechanisms that may explain metal tolerance, focussing on the interactions between insoluble metal species and extracellular fungal metabolites. In particular, we demonstrate that fungal strains derived from polluted and unpolluted soils mobilize insoluble inorganic zinc compounds to different extents. Strains from polluted soils showed in fact little ability to solubilize Zn from both ZnO and Zn3(PO4)2, whereas strains from unpolluted soils showed a higher solubilization potential. This different behaviour was confirmed when the solubilization abilities of a wider range of fungal strains (25 isolates) was examined. Induction of organic acids (malate and citrate) by the metal compounds was at least in part responsible for metal solubilization. Our results suggest that ericoid mycorrhizal strains from polluted and unpolluted soils may interact differently with metal compounds. We speculate that this may reflect specific strategies to maintain homeostasis of essential metals under different soil conditions.  相似文献   

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