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1.
Four most efficient phytase and phosphatase producing fungi belonging to genera Aspergillus, Trichoderma, and Penicillium were isolated from the rhizosphere soil of leguminous, cereal, and vegetable crops. Efficacy order of fungi in terms of phytate hydrolysis under laboratory conditions was Aspergillus > Penicillium > Trichoderma. The test fungi released more of extracellular (E) phytase than intracellular (I) phytase (E: I- 3.44 - 6.03:1) and produced acid phosphatase activity ranging from 367- 830 μmol pNP ml?1 h?1. Aspergillus niger possessed the twin ability of phosphate mineralization and solubilization. The incubation studies in compost-amended soil exhibited the higher competence of Penicillium chrysogenum to improve the soil available P and increase the level of extractable organic P under alkaline soil to benefit P nutrition. Developing microbial inoculant using P. chrysogenum strain and its subsequent application to soil may help the marginal farmer to replenish soil P more economically compared to chemical fertilizer.  相似文献   

2.
Seven most efficient phytase and phosphatases producing fungi were isolated from the soils of arid and semi-arid regions of India and tested for their efficiency on hydrolysis of two important organic P compounds: phytin and glycerophosphate. The native soil organic P may be exploited after using these organisms as seed inoculants, to help attain higher P nutrition of plants. The identified organisms belong to the three genera: Aspergillus, Emmericella and Penicillium. Penicillium rubrum released the most acid into the medium during growth. Aspergillus niger isolates were found to accumulate biomass the fastest. A significant negative correlation (r=−0.593,n=21, p<0.01) was observed between the development of fungal mat and pH of the media. The extracellular (E) phosphatases released by different fungi were less than their intracellular (I) counterpart, but the trend was reversed in case of phytase production. The E:I ratio of different fungi ranged from 0.39 to 0.86 for acid phosphatase, 0.29 to 0.41 for alkaline phosphatases and 9.4 to 19.9 for phytase. The efficiency of hydrolysis of different organic P compounds of different fungi varied from 2.12-4.85 μg min−1 g−1 for glycerophosphate to 0.92-2.10 μg min−1 g−1 for phytin. The trend of efficiency was as follows: Aspergillus sp.>Emmericella sp.>Penicillium sp. The results indicated that the identified fungi have enough potential to exploit native organic phosphorus to benefit plant nutrition.  相似文献   

3.
Rhizobium leguminosarum biovarviceae strain TAL 1236 growing on different organic P compounds as sources of phosphate exhibited phosphatase activities. The strain was able to produce both acid and alkaline phosphatase. However, its ability to produce alkaline phosphatase was much higher. When cellular phosphate fell to 0.115% of cell protein, cellular and extracellular phosphatase activities were enhanced. Mg2+, Co2+, and Ca2+ stimulated the activity of alkaline phosphatase more than acid phosphatase. However, Mn2+ and Fe2+ activated acid phosphatase rather than alkaline phosphatase. It may be concluded thatR. leguminosarum contributes significantly to the release of P from organic compounds through the action of phosphatase which can be activated by a range of cations.  相似文献   

4.
Bacillus coagulans, a phosphatase- and phytase-producing bacterium was isolated and tested under greenhouse conditions and in the field in a loamy sand soil. Bacterial population build-up and efficiency was compared under sterilized and non-sterilized soil conditions. Exploitation of plant unavailable (poorly soluble) P was higher in sterilized soil, mainly due to an increased bacteria population. A gradual increase in microbial build-up of up to 21 times the inoculated population was observed over a 4-week period under the sterilized soil condition. Clusterbean influenced acid phosphatase and phytase activity. The depletion of organic P was much higher than the depletion of mineral and phytin P. The microbial contribution to the hydrolysis of the different P fractions was significantly higher than the plant contribution. The maximum effect of inoculation on different enzyme activities (acid phosphatase, alkaline phosphatase, phytase and dehydrogenase) was observed in pants between 5 and 8 weeks of age. A significant improvement in plant biomass (25%), root length (28%), plant P concentration (22%), seed (19%) and straw yield (28%) resulted from inoculation. The results suggested that B. coagulans produces phosphatases and phytase, which mobilized P from unavailable native P sources and enhanced the production of clusterbean.  相似文献   

5.
Periphytic biofilms exist widely in paddy fields, but their influences on the hydrolysis of organic phosphorus(P) have rarely been investigated. In this study,a periphytic biofilm was incubated in a paddy soil solution, and hydrolysis kinetic parameters(half-saturation constant(Km) and maximum catalytic reaction rate(Vmax)), optimal environmental conditions, substrate specificity, and response to different P regimes of the phosphatase activities in the periphytic biofilm were determined, in order to characterize extracellular phosphatase activities in periphytic biofilms from paddy fields. The results indicated that the periphytic biofilm could produce an acid phosphomonoesterase(PMEase), an alkaline PMEases, and a phosphodiesterase(PDEase). These three phosphatases displayed high substrate affinity, with Km values ranging from 141.03 to 212.96 μmol L-1. The Vmax/Km ratios for the phosphatases followed the order of alkaline PMEase > acid PMEase > PDEase, which suggested that the PMEases, especially the alkaline PMEase, had higher catalytic efficiency. The optimal pH was 6.0 for the acid PMEase activity and 8.0 for the PDEase activity, and the alkaline PMEase activity increased with a pH increase from 7.0 to 12.0. The optimal temperature was 50℃ for the PMEases and 60℃ for the PDEase. The phosphatases showed high catalytic efficiency for condensed P over a wide pH range and for orthophosphate monoesters at pH 11.0, except for inositol hexakisphosphate at pH 6.0. The inorganic P supply was the main factor in the regulation of phosphatase activities. These findings demonstrated that the periphytic biofilm tested had high hydrolysis capacity for organic and condensed P,especially under P-limited conditions.  相似文献   

6.
The fungal PhyA protein, which was first identified as an acid optimum phosphomonoesterase (EC 3.1.3.8), could also serve as a vanadate haloperoxidase (EC 1.11.1.10) provided the acid phosphatase activity is shut down by vanadate. To understand how vanadate inhibits both phytate and pNPP degrading activities of fungal PhyA phytase and bacterial AppA2 phytase, kinetic experiments were performed in the presence and absence of orthovanadate and metavanadate under various acidic pHs. Orthovanadate was found to be a potent inhibitor at pH 2.5 to 3.0. A 50% activity of fungal phytase was inhibited at 0.56 μM by orthovanadate. However, metavanadate preferentially inhibited the bacterial AppA2 phytase (50% inhibition at 8 μM) over the fungal phytase (50% inhibition at 40 μM). While in bacterial phytase the K(m) was not affected by ortho- or metavanadate, the V(max) was reduced. In fungal phytase, both the K(m) and V(max) was lowered. The vanadate exists as an anion at pH 3.0 and possibly binds to the active center of phytases that has a cluster of positively charged Arg, Lys, and His residues below the enzymes' isoelectric point (pI). The active site fold of haloperoxidase was shown to be very similar to fungal phytase. The vanadate anions binding to cationic residues in the active site at acidic pH thus serve as a molecular switch to turn off phytase activity while turning on the haloperoxidase activity. The fungal PhyA phytase's active site housing two distinct reactive centers, one for phosphomonoesterase and the other for haloperoxidase, is a unique example of how one protein could catalyze two dissimilar reactions controlled by vanadate.  相似文献   

7.
Summary The distribution of phosphatase activity and of phosphate fractions of the soil in the proximity of roots was studied in order to evaluate the significance of phosphatases in P nutrition of various plants (Brassica oleracea, Allium cepa, Triticum aestivum, Trifolium alexandrinum). A considerable increase in both acid and alkaline phosphatase activity in all the four soil-root interfaces was observed. Maximum distances from the root surface at which activity increases were observed ranged from 2.0 mm to 3.1 mm for acid phosphatase and from 1.2 mm to 1.6 mm for alkaline phosphatase. The increase in phosphatase activity depended upon plant age, plant species and soil type. A significant correlation was noticed between the depletion of organic P and phosphatase activity in the rhizosphere soil of wheat (r = 0.99**) and clover (r = 0.97**). The maximum organic P depletion was 65% in clover and 86% in wheat, which was observed within a distance from the root of 0.8 mm in clover and 1.5 mm in wheat. Both the phosphatases in combination appear to be responsible for the depletion of organic P.  相似文献   

8.
The chloroform fumigation technique has been successfully employed to quantify intracellular and extracellular urease and arylsulfatase activities in soil. In this study, the same approach was evaluated for its ability to differentiate between various pools of phosphomonoesterase activities in soils and reference proteins purified from plant and microbial sources. The activities of acid and alkaline phosphatases were assayed in 10 surface soils and reference proteins at their optimal pH values before and after chloroform fumigation and in the presence and absence of toluene. Chloroform fumigation decreased the activities of acid and alkaline phosphatases in soils, on average, by 6 and 8%, respectively. Similarly, the activities of two purified reference enzyme proteins were decreased after fumigation, with acid and alkaline phosphatase activities exhibiting a reduction of 17 and 8%, respectively. Toluene treatment caused an increase in the activities of acid and alkaline phosphatases by 8 to 18% in nonfumigated soils, but showed no effect in the fumigated soils. Average enzyme protein concentrations, calculated for the 10 soils based on the activity values of the soils and the specific activity of the purified enzymes (i.e., activity values per mg protein), were 22.5 and 2.1 mg protein (kg soil)—1 for acid and alkaline phosphatase, respectively. The decrease in enzyme activity by the fumigant was either by direct denaturing of the periplasmic and extracellular portion of the particular protein after lysis of the microbial cell membrane, by absorption and/or inhibition of the released phosphomonoesterases by organic and inorganic constituents or by degradation of the protein by soil proteases. The ratios of acid phosphatase protein concentrations relative to organic C in six soils were significantly, but negatively correlated with soil organic C, suggesting differences in organic C quality. Comparison of the activity values of soil phosphatases with those of the protein concentrations present in soils indicated that alkaline phosphatase has greater catalytic efficiency than does acid phosphatase.  相似文献   

9.
Most studies on phosphatase activity in soils have been concerned with acid phosphatase. This study was conducted to determine the activity of phosphomonoesterases (acid and alkaline phosphatases), phosphodiesterase, and “phosphotriesterase”. The results indicate that acid phosphatase is predominant in acid soils and that alkaline phosphatase is predominant in alkaline soils. With universal buffer, the pH optima of phosphodiesterase and phosphotriesterase were at pH 10. The activities of these phosphatases in soils were much lower than those of the acid and alkaline phosphatases. Studies on the effects of various soil treatments on the activity of phosphatases in soils indicated that air-drying increased the activity of acid phosphatase and phosphotriesterase, decreased the activity of alkaline phosphatase, but did not affect the activity of phosphodiesterase. Steam sterilization of soils at 121 C for 1 h inactivated alkaline phosphatase, phosphodiesterase, and phosphotriesterase, but did not completely inactivate acid phosphatase. Addition of toluene to the incubation mixture did not markedly affect the activity of acid phosphatase, alkaline phosphatase, phosphodiesterase, but increased the activity of phosphotriesterase in soils.Studies of the kinetic parameters of phosphatases in the soils studied showed that the Km values ranged from 1.11 to 3.40 mm for acid phosphatase. from 0.44 to 4.94 mm for alkaline phosphatase, and from 0.25 to 1.25 mm for phosphodiesterase. Expressed as μg p-nitrophenol released·h?1·g?1 soil, the Vmax values ranged from 200 to 625 for acid phosphatase, from 124 to 588 for alkaline phosphatase, and from 46 to 127 for phosphodiesterase. The substrate of phosphotriesterase (tris-p-nitrophenyl phosphate) is insoluble in water; hence, the Km and Vmax values of this enzyme in soils could not be determined.  相似文献   

10.
Phosphate in solutions of model esters and polyphosphates (glucose phosphate, inositol hexaphosphate, pyrophosphate, ribonucleic acid, tripolyphosphate and trimetaphosphate) was quantitatively released in <6 h by acid phosphatase or phytase at pH 5.0. Interference from insoluble, ion association complexes formed between protein in the enzymes and the phosphomolybdenum blue during the colorimetric determination of the molybdate reactive phosphorus released was removed by adding dimethyl sulphoxide. Filtered (0.45 μm) soil solution from a peaty soil contained 590 μg dm–3 total dissolved phosphorus (TDP), of which 13% was molybdate reactive phosphorus (MRP), 26% dissolved organic phosphorus (DOP) and 61% dissolved condensed phosphorus (DCP). When acid phosphatase was added to the soil solution under the conditions used to hydrolyse the model compounds, MRP increased to 54% of the TDP in about 10 h and then remained constant. From a mass balance, at least 25% of the DCP was hydrolysed. Incubation of the soil solution at 35°C without enzyme increased MRP to 44% of the TDP, reflecting native enzyme activity. Soil solution containing a higher concentration of TDP (1.27 mg dm–3) was also obtained. The distribution of MRP, DOP and DCP fractions was similar but acid phosphatase hydrolysed a greater proportion of the P and MRP increased to 64% of the TDP and at least 40% of the DCP was hydrolysed. The results of hydrolysis with phytase were similar to those with acid phosphatase. The protection of part of the DOP or DCP fraction from hydrolysis was likely caused by occlusion within colloids or the existence of P compounds unlike those of the model substrates. Received: 7 January 1996  相似文献   

11.
Fungal phytases belonging to "histidine acid phosphatase" or HAP class of phosphohydrolases that catalyze the hydrolysis of phytic acid could also hydrolyze O-phospho-L-tyrosine, which is also called phosphotyrosine. Two phytases from Aspergillus niger and Aspergillus awamori with pH optima 2.5 were tested for phosphotyrosine hydrolase activity; both enzymes cleaved the phosphomonoester bond of phosphotyrosine efficiently at acidic pH. The Km for phosphotyrosine ranged from 465 to 590 microM as opposed to 135 to 160 microM for phytate. The Vmax, however, is 2-4 times higher for phosphotyrosine than it is for phytate. The catalytic efficiency of phytase for phosphotyrosine is on the same order as it is for phytate (3.5 x 10(6) to 1.6 x 10(7) M(-1) s(-1)); the pH versus activity profile for phosphotyrosine is, however, different from what it is for phytate. The temperature optima shifted 5 degrees C higher to 70 degrees C when phosphotyrosine was used as the substrate. Taken together, the kinetic data show that fungal HAPs that are known as PhyB are capable of cleaving the phosphomonoester bond in phosphotyrosine. This is the first time that phosphotyrosine phosphatase (PTPase) activity has been reported for the subgroup of HAP known as phytase.  相似文献   

12.
Enzyme activities have the potential to indicate biological functioning of soils. In this study, soil urease, dehydrogenase, acid phosphatase and invertase activities and fluorescein diacetate（FDA） hydrolysis were measured in two red soils spiked with Pb^2＋ ranging from 0 to 2 400 mg kg^-1 to relate the enzyme activity values to both plant growth and the levels of available and total Pb^2＋ concentrations in soils, and to examine the potential use of soil enzymes to assess the degrees of Pb contamination. Soil samples were taken for enzyme activities assaying during 3 month’s incubation and then after planting of celery（Apium graveolens L.） and Chinese cabbage（Brassica chinensis L.）. Enzyme activities in the red soil derived from arenaceous rock（RAR） were generally lower than those in the red soil developed on Quaternary red earths（REQ）. At high Pb^2＋ loadings, in both incubation and greenhouse studies, urease activity and FDA hydrolysis were significantly inhibited. But there were no significant relationships between soil dehydrogenase, acid phosphatase or invertase activity and soil Pb^2＋ loadings in both RAR and REQ soils. The growth of celery and Chinese cabbage increased soil urease activity and FDA hydrolysis, but had minimal effect on dehydrogenase and invertase activities. There were positive correlations between celery biomass and soil urease activity and FDA hydrolysis. These results demonstrate that urease activity and FDA hydrolysis are more sensitive to Pb^2＋ than acid phosphatase, dehydrogenase and invertase activities in the RAR and REQ soils.  相似文献   

13.
Summary The effects of heavy metals on microbial biomass and activity were investigated in 30 urban soils, contaminated mainly with Zn and Pb to different extents, in terms of the physicochemical and biological characteristics of the soils. Evaluated by simple and multiple regression analyses, the microbial biomass was not affected significantly by easily soluble Zn + Pb (extractable with 0.1 NHCI). The biomass was accounted for as a function of cation exchange capacity (CEC), total organic C and the numbers of fungal colonies present (R 2 = 0.692). Carbon dioxide evolution from soils, which reflected microbial activity, was studied on soils incubated with microbial-promoting substrates (glucose and ammonium sulfate) or without. Carbon dioxide evolution was negatively related to Zn+Pb, and this inhibitory effect of the metals was greater in the soils incubated with substrates. Carbon dioxide evolution in soils with substrates was closely related to Zn+Pb, bacterial numbers and the numbers of fungal colonies (R 2 = 0.718). Carbon dioxide evolution in soils without substrates was accounted for as a function of Zn + Pb, biomass and the C/N ratio (R 2 = 0.511). Using these relationships, the effects of heavy metals on soil microorganisms are discussed in terms of metabolically activated and dormant populations.  相似文献   

14.
Soil microbes and phosphatase enzymes play a critical role in organic soil phosphorus (P) cycling. However, how long-term P inputs influence microbial P transformations and phosphatase enzyme activity under grazed pastures remains unclear. We collected top-soil (0–75 mm) from a grazed pasture receiving contrasting P inputs (control, 188 kg ha−1 year−1 of single super phosphate [SSP], and 376 kg ha−1 year−1 of SSP) for more than 65 years. Olsen P, microbial biomass P, and acid and alkaline phosphatase enzyme activities were measured regularly over a 2-year period. Pasture dry matter and soil chemical properties were also investigated. Results showed that long-term P inputs significantly increased pasture dry matter, total N, and the concentrations of NO 3 – –N but significantly decreased soil pH and the concentrations of NH 4 + –N. Total C was not affected by P fertilization. Although Olsen P significantly increased with increasing long-term P inputs, microbial biomass P was similar under P fertilized treatments. Long-term P inputs decreased acid phosphatase activity but increased alkaline phosphatase activity. Microbial biomass P was similar across seasons in the control but decreased in spring and autumn while increased in summer and winter under P fertilized treatments. Acid and alkaline phosphatase activities were significantly affected by season and followed similar seasonal trends being maximum in summer and minimum in winter regardless of P treatment. Correlation and principal component analysis revealed that acid and alkaline phosphatase activities were significantly positively correlated with soil temperature and significantly negatively correlated with soil moisture. In contrast, Olsen P and microbial biomass P were weakly correlated with environmental conditions. The findings of this study highlight the intertwined relationship between organic P cycling and the availability of C and N in soil systems and the need to integrate both soil moisture and temperature in models predicting organic P mineralization, especially in the context of global climate change.  相似文献   

15.
The role of disulfide bridges in the folding of Aspergillus niger phytase pH 2.5-optimum (PhyB) was investigated using dynamic light scattering (DLS). Guanidinium chloride (GuCl) at 1.0 M unfolded phytase; however, its removal by dialysis refolded the protein. The thiol reagent tris(2-carboxyethyl)phosphine (TCEP) reduces the refolding activity by 68%. The hydrodynamic radius (R(H)) of PhyB phytase decreased from 5.5 to 4.14 nm when the protein was subjected to 1.0 M GuCl concentration. The active homodimer, 183 kDa, was reduced to a 92 kDa monomer. The DLS data taken together with activity measurements could indicate whether refolding took place or not in PhyB phytase. The correlation between molecular mass and the state of unfolding and refolding is a very strong one in fungal phytase belonging to histidine acid phosphatase (HAP). Unlike PhyA phytase, for which sodium chloride treatment boosted the activity at 0.5 M salt concentration, PhyB phytase activity was severely inhibited under identical condition. Thus, PhyA and PhyB phytases are structurally very different, and their chemical environment in the active site and substrate-binding domain may be different to elicit such an opposite reaction to monovalent cations.  相似文献   

16.
Phosphorus (P) deficiency is a major limitation to agricultural production in many parts of the world. It is therefore desirable to identify plants with enhanced abilities to utilize P more efficiently. Exudation of phosphatase from roots may improve P availability, yet there is little direct evidence for this. Here we report the dynamics of organic P in the rhizosphere of plants that have enhanced rhizosphere phosphatase activity. Agroforestry species and transgenic subterranean clover (engineered to produce phytase) were compared with crop and wild‐type plant controls, respectively. Depletion of organic P was measured in pools defined by chemical extraction, solution 31P NMR spectroscopy, and microbial immobilization of radio‐isotopic P. Plants that had greater extracellular phosphatase activity depleted more organic P from P‐deficient Oxisols than control plants. Depleted organic P forms were primarily phosphate monoesters. Plants with enhanced extracellular phosphatase activity also had access to a pool of soil P that was less isotopically exchangeable. Transgenic subterranean clover that expresses a microbial phytase gene appeared to have greater access to recently immobilized P, whereas plants expressing endogenous phosphatases utilized the unlabelled portion of soil organic P to a greater extent. Collectively, these results indicate that the enhancement of phosphatase activity in the rhizosphere of plants is implicated in the depletion of organic P forms from soils, most notably orthophosphate monoesters, whilst also suggesting that there is some exclusivity to the pools of organic P utilized by plants and microorganisms.  相似文献   

17.
Dehydrogenase activity, alkaline phosphatase activity and NH4 +, NO2 − and NO3 − concentrations were monitored in an aridisol treated with three commercially available humic amendments. The materials were of plant residue, lignite and peat origins. The humus plant residues, fulvic acids, with a high content of Kjeldahl-N, sustained high enzyme activities and highest levels of NH4 +, NO2 − and NO3 −. Humus lignite (mainly humic acids) produced the highest dehydrogenase activity, whereas the alkaline phosphatase activity was not as high as that amendment with humus plant residues. The lower activity of alkaline phosphatase could not be attributed to the higher P content of humus lignite. Nitrification was also low, probably due to the low N content of this fertilizer. The amendment of humus peat origin (only humic acids) did not increase enzyme activity or inorganic N concentrations of soil. Our results show that although these materials are widely utilized and recommended as microbial and plant activators, they all behave very differently, and the effects on soil microbiological activity cannot be predicted solely on the basis of their humic and/or fulvic acid contents.  相似文献   

18.
Co‐application of biosolids and water treatment residuals (WTR) land has not been extensively studied but may be beneficial by sorbing excess biosolid‐borne or soil phosphorus (P) onto WTR, reducing the likelihood of off‐site movement. Reduction of excess soil P may affect the role of specific P‐cleaving enzymes. The research objective was to understand the long‐term effects of single co‐applications and the short‐term impacts of repeated co‐applications on soil acid phosphomonoesterase, phosphodiesterase, pyrophosphatase, and phytase enzyme activities. Test plots were 7.5 × 15 m with treatments consisting of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha?1; 10 Mg biosolids ha?1) surface co‐applied once in 1991 or reapplied in 2002. Control plots consisted of those that received no WTR–biosolids co‐applications and plots that received only 10 Mg biosolids ha?1. Plots were sampled to a 5‐cm depth in 2003 and 2004, and soil phosphatases and phytase enzyme activities were measured. Soil phosphodiesterase activity decreased in WTR‐amended plots, and pyrophosphatase activity decreased with increasing WTR application rates. In contrast, acid phosphatase and phytase activity increased with WTR addition, with WTR application possibly triggering a deficiency response causing microorganisms or plants to secrete these enzymes. Biosolids and WTR co‐applications may affect enzymatic strategies for P mineralization in this study site. Reductions in phosphodiesterase activity suggest less P mineralization from biomass sources, including nucleic acids and phospholipids. Increased acid phosphatase and phytase activities indicate that ester‐P and inositol‐P may be important plant‐available P sources in soils amended with WTR.  相似文献   

19.
The aim of this study was to provide data to assess the additive effects of soil salinity on the toxicity of Cd to soil alkaline phosphatase (EC 3.1.3.1). Two soils (Langroud acid soil and Shervedan calcareous soil) were artificially salinized with NaCl. The natural and salinized soils were treated with CdSO4 solutions to give a Cd concentration in the range 3–5000 mg kg?1. Soil alkaline phosphatase activity was measured after 3 days of incubation. Salinity enhanced the extractable Cd concentration in both Langroud and Shervedan soils. The percentage of soil alkaline phosphatase activity inhibited by Cd was significantly increased from 27.8 to 45 in the Langroud acid soil as salinity increased from natural levels to 28 dS m?1. An increase in the inhibition percentage was not observed in the Shervedan soil. Lower values for the ecological dose causing 50% inhibition (ED50) under saline conditions in the Shervedan soil supported the hypothesis that Cd may be more toxic to soil alkaline phosphatase when the soil is more saline. We conclude that Cd toxicity to soil alkaline phosphatase is salinity dependent and that higher Cd concentrations under saline conditions are probably responsible for the enhanced Cd toxicity to soil alkaline phosphatase.  相似文献   

20.
淹水厌氧培养对水稻土中酶活性的影响   总被引：4，自引：0，他引：4  
WANG Xiao-Chang  LU Qin 《土壤圈》2006,16(4):532-539
An incubation experiment with soil water content treatments of 0.15 （W1）, 0.20 （W2）, and 0.40 （W3） g g^-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, P, and S cycling in a paddy soil from the Taihu Lake region, China, under waterlogged and aerobic conditions. Compared with air-dried soil, waterlogging resulted in a significant decrease （P ≤ 0.05） of fluorescein diacetate （FDA） and /3-D-glucosidase activities, and this effect was enhanced with increasing waterlogging time. Waterlogging also significantly inhibited （P ≤ 0.05） arylsulfatase as well as alkaline and acid phosphatase activities, but did not decrease the activities with the increase in waterlogging time. Short-term waterlogging did not affect urease activity, but prolonged waterlogging decreased it markedly. In contrast, the aerobic incubation （W1 and W2 treatments） significantly increased （P ≤ 0.05） FDA, alkaline phosphatase, and /3-D-glucosidase activities. With aerobic treatments the activities of FDA and alkaline phosphatase increased with incubation time, whereas /3-D-glucosidase activity decreased. A significant difference （P ≤ 0.05） was usually observed between the W1 and W2 treatments for the activities of FDA as well as alkaline and acid phosphatase; however,/3-D-glucosidase and urease were usually not significant （P ≤ 0.05）. No activity differences were observed between waterlogging and aerobic incubation for arylsulfatase and urease.  相似文献   

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