不同浓度Fe2+与Zn2+对羊草幼苗生长和生理特性的影响

以羊草幼苗为研究对象,通过调整全营养培养基(CK,0.05 mmol/L Fe²⁺、0.015 mmol/L Zn²⁺)中铁或者锌含量设置0、10倍、20倍Fe²⁺(Zn²⁺)浓度处理Fe₀(Zn₀)、Fe₁₀(Zn₁₀)、Fe₂₀(Zn₂₀),以及在高铁培养基中单独添加0.15 mmol/L Zn²⁺或同时添加10 mmol/L Ca²⁺、5 mmol/L Mg²⁺、20 mmol/L K⁺处理,测定培养6 d后幼苗生长指标和矿质元素含量、以及高铁(Fe₂₀)处理下幼苗根中抗氧化指标和相关基因表达量,探究不同浓度Fe²⁺、Zn²⁺对羊草幼苗生长、矿质元素吸收积累及抗氧化指标、基因表达的影响。结果表明：(1)缺锌(Zn₀)显著抑制羊草幼苗鲜重的增加和Zn元素的积累,但促进Fe、Mg元素的积累;高浓度锌(Zn₁₀、Zn₂₀)显著促进幼苗叶片生长和Zn元素的积累;缺铁(Fe₀)显著抑制幼苗的根长、鲜重和Fe元素的积累,促进Mg、Zn元素的积累;高浓度铁(Fe₁₀、Fe₂₀)显著抑制羊草幼苗根叶生长、根毛发育和Ca、Zn、Mg、K元素的积累。(2)增加Zn²⁺和Ca²⁺、Mg²⁺、K⁺浓度无法恢复高铁胁迫对幼苗生长的抑制作用。(3)高浓度铁(Fe₂₀)处理羊草幼苗48 h后,根部过氧化物酶、超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶活性和丙二醛、抗坏血酸、还原型谷胱甘肽含量显著升高;烟酰胺合成酶基因、过氧化物酶基因表达量显著下调,植物类萌发素蛋白基因表达量显著上调。研究发现,羊草幼苗生长发育和矿质元素积累对环境中Zn²⁺浓度变化不敏感,却受到环境中高浓度Fe²⁺的显著抑制,并造成严重的氧化胁迫伤害,这种伤害无法在添加Zn²⁺或同时添加Ca²⁺、Mg²⁺、K⁺的条件下恢复。     

Ca<Superscript>2+</Superscript> increases the specific coenzyme Q<Subscript>10</Subscript> content in <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

Of various metal ions (Ca²⁺, Cr³⁺, Cu²⁺, Fe²⁺, Mg²⁺, Mn²⁺, Ni²⁺ and Zn²⁺) added to the culture medium of Agrobacterium tumefaciens at 1 mM, only Ca²⁺ increased Coenzyme Q10 (CoQ₁₀) content in cells without the inhibition of cell growth. In a pH-stat fed-batch culture, supplementation with 40 mM of CaCO₃ increased the specific CoQ₁₀ content and oxidative stress by 22.4 and 48%, respectively. Also, the effect of Ca²⁺ on the increase of CoQ₁₀ content was successfully verified in a pilot-scale (300 L) fermentor. In this study, the increased oxidative stress in A. tumefaciens culture by the supplementation of Ca²⁺ is hypothesized to stimulate the increase of specific CoQ₁₀ content in order to protect the membrane against lipid peroxidation. Our results improve the understanding of Ca²⁺ effect on CoQ₁₀ biosynthesis in A. tumefaciens and should contribute to better industrial production of CoQ₁₀ by biological processes.     

A thermoalkaliphilic lipase of <Emphasis Type="Italic">Geobacillus</Emphasis> sp. T1

A thermoalkaliphilic T1 lipase gene of Geobacillus sp. strain T1 was overexpressed in pGEX vector in the prokaryotic system. Removal of the signal peptide improved protein solubility and promoted the binding of GST moiety to the glutathione-Sepharose column. High-yield purification of T1 lipase was achieved through two-step affinity chromatography with a final specific activity and yield of 958.2 U/mg and 51.5%, respectively. The molecular mass of T1 lipase was determined to be approximately 43 kDa by gel filtration chromatography. T1 lipase had an optimum temperature and pH of 70°C and pH 9, respectively. It was stable up to 65°C with a half-life of 5 h 15 min at pH 9. It was stable in the presence of 1 mM metal ions Na⁺, Ca²⁺, Mn²⁺, K⁺ and Mg²⁺ , but inhibited by Cu²⁺, Fe³⁺ and Zn²⁺. Tween 80 significantly enhanced T1 lipase activity. T1 lipase was active towards medium to long chain triacylglycerols (C10–C14) and various natural oils with a marked preference for trilaurin (C12) (triacylglycerol) and sunflower oil (natural oil). Serine and aspartate residues were involved in catalysis, as its activity was strongly inhibited by 5 mM PMSF and 1 mM Pepstatin. The T _m for T1 lipase was around 72.2°C, as revealed by denatured protein analysis of CD spectra.     

Expression,purification and characterization of pectate lyase A from <Emphasis Type="Italic">Aspergillus nidulans</Emphasis> in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Pectate lyase A (PelA) of Aspergillus nidulans was successfully expressed in Escherichia coli and effectively purified using a Ni²⁺-nitrilotriacetate-agarose column. Enzyme activity of the recombinant PelA could reach 360 U ml⁻¹ medium. The expressed PelA exhibited its optimum level of activity over the range of pH 7.5–10 at 50°C. Mn²⁺, Ca²⁺, Fe²⁺, Mg²⁺ and Fe³⁺ ions stimulated the pectate lyase activity, but Cu²⁺ and Zn²⁺ inhibited it. The recombinant PelA had a V _max of 77 μmol min⁻¹ mg⁻¹ and an apparent K _m of 0.50 mg ml⁻¹ for polygalacturonic acid. Low-esterified pectin was the optimum substrate for the PelA, whereas higher-esterified pectin was hardly cleaved by it. PelA efficiently macerated mung bean hypocotyls and potato tuber tissues into single cells.     

Solubilization of Phosphates and Micronutrients by the Plant-Growth-Promoting and Biocontrol Fungus Trichoderma harzianum Rifai 1295-22

We investigated the capability of the plant-growth-promoting and biocontrol fungus Trichoderma harzianum Rifai 1295-22 (T-22) to solubilize in vitro some insoluble or sparingly soluble minerals via three possible mechanisms: acidification of the medium, production of chelating metabolites, and redox activity. T-22 was able to solubilize MnO₂, metallic zinc, and rock phosphate (mostly calcium phosphate) in a liquid sucrose-yeast extract medium, as determined by inductively coupled plasma emission spectroscopy. Acidification was not the major mechanism of solubilization since the pH of cultures never fell below 5.0 and in cultures containing MnO₂ the pH rose from 6.8 to 7.4. Organic acids were not detected by high-performance thin-layer chromatography in the culture filtrates. Fe₂O₃, MnO₂, Zn, and rock phosphate were also solubilized by cell-free culture filtrates. The chelating activity of T-22 culture filtrates was determined by a method based on measurement of the equilibrium concentration of the chrome azurol S complex in the presence of other chelating substances. A size exclusion chromatographic separation of the components of the culture filtrates indicated the presence of a complexed form of Fe but no chelation of Mn. In liquid culture, T. harzianum T-22 also produced diffusible metabolites capable of reducing Fe(III) and Cu(II), as determined by the formation of Fe(II)-Na₂-bathophenanthrolinedisulfonic acid and Cu(I)-Na₂-2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid complexes. This is the first report of the ability of a Trichoderma strain to solubilize insoluble or sparingly soluble minerals. This activity may explain, at least partially, the ability of T-22 to increase plant growth. Solubilization of metal oxides by Trichoderma involves both chelation and reduction. Both of these mechanisms also play a role in biocontrol of plant pathogens, and they may be part of a multiple-component action exerted by T-22 to achieve effective biocontrol under a variety of environmental conditions.     

The spatial distribution of cations in nematocytes of Hydra vulgaris

The spatial distribution of cations was assayed qualitatively and quantitatively in tentacular nematocytes of Hydra vulgaris in a scanning transmission electron microscope by means of x-ray microanalysis performed on 100 nm thick freeze-dried cryosections. The matrix of undischarged cysts (stenoteles, desmonemes and isorhizas) was found to contain mainly K⁺. In isolated nematocysts of Hydra the intracapsular potassium can be readily substituted by practically any other mono- and divalent cation (Na⁺, NH₄ ⁺, Mn²⁺, Co²⁺, Mg²⁺, Ca²⁺, Fe²⁺) all, except Fe²⁺, without impairing the ability of the cyst to respond to the chemical triggering with dithioerythritol or proteases. Monovalent cations increase the osmotically generated intracapsular pressure compared to divalent ions.     

Toward a Reversible Mn4+/Mn2+ Redox Reaction and Dendrite‐Free Zn Anode in Near‐Neutral Aqueous Zn/MnO2 Batteries via Salt Anion Chemistry

Rechargeable aqueous Zn/MnO₂ batteries are very attractive large‐scale energy storage technologies, but still suffer from limited cycle life and low capacity. Here the novel adoption of a near‐neutral acetate‐based electrolyte (pH ≈ 6) is presented to promote the two‐electron Mn⁴⁺/Mn²⁺ redox reaction and simultaneously enable a stable Zn anode. The acetate anion triggers a highly reversible MnO₂/Mn²⁺ reaction, which ensures high capacity and avoids the issue of structural collapse of MnO₂. Meanwhile, the anode‐friendly electrolyte enables a dendrite‐free Zn anode with outstanding stability and high plating/stripping Coulombic efficiency (99.8%). Hence, a high capacity of 556 mA h g^?1, a lifetime of 4000 cycles without decay, and excellent rate capability up to 70 mA cm^?2 are demonstated in this new near‐neutral aqueous Zn/MnO₂ battery by simply manipulating the salt anion in the electrolyte. The acetate anion not only modifies the surface properties of MnO₂ cathode but also creates a highly compatible environment for the Zn anode. This work provides a new opportunity for developing high‐performance Zn/MnO₂ and other aqueous batteries based on the salt anion chemistry.     

Interactions between gramicidin S and its producer,Bacillus brevis

Gramicidin S (GS) inhibition of germination outgrowth ofBacillus brevis spores was reversed completely by a short pretreatment with sodium dodecyl sulfate, moderately by ethanol or by incubation at pH 10 but not by incubation at pH 4. Of five metal ions tested (Na⁺, Mg²⁺, Fe²⁺, Cu²⁺, Ca²⁺), only Ca²⁺ reversed GS inhibition. When Ca²⁺ (but not the other four metal ions) was added to the growth medium, there was a considerable portion of the biosynthesized GS found in the extracellular fluid. These findings are interpreted in terms of the binding of GS to the external layers of theB. brevis spore.     

Effect of calcium on synthesis of dipicolinic acid inPenicillium citreoviride and its feedback resistant mutant

Dipicolinic acid synthesis inPenicillium citreoviride strain 3114 was inhibited by Ca²⁺ ions, but not by Ba²⁺, Cu²⁺or Fe²⁺. Among the metals tested, only Zn²⁺ inhibited the synthesis of dipicolinic acid and promoted sporulation. None of these metals reversed the inhibition by Ca²⁺ or Zn²⁺. A mutant 27133-dpa-ca selected for resistance to feedback inhibition by dipicolinic acid: Ca²⁺ complex showed cross-resistance to inhibition by dipicolinic acid: Zn²⁺. Both 3114 and271 33-dpa-ca excreted a number of aliphatic and amino acids during secondary metabolism of dipicolinic acid. In the presence of 1000 ppm of Ca²⁺, accumulation of citric acid and α-aminoadipic acid was completely inhibited under conditions of inhibition of dipicolinic acid in parent strain 3114 but not in the mutant. Citric acid with or without Ca²⁺ did not inhibit thede novo synthesis of dipicolinic acid in the strain 3114. In fact, citric acid in the presence of Ca²⁺ improved significantly rate of dipicolinic acid synthesis. Apart from resistance to feed back inhibition by dipicolinic acid: Ca²⁺ complex, mutant differed from the parent in three other aspectsviz. (i) dipicolinic acid synthesis was not subject to catabolite repression by glucose, (ii) sporulation as well as dipicolinic acid synthesis was dependent on the presence of Ca²⁺ ions in the medium and (iii) Mg²⁺ requirement for the mutant increased three fold. Higher requirement of the Mg²⁺ could be partially relieved by Ca²⁺ during secondary metabolism. The results support the inference thatde novo synthesis of dipicolinic acid is regulated through feedback inhibition by dipicolinic acid: Ca²⁺complex.     

Defect Engineering of Oxygen‐Deficient Manganese Oxide to Achieve High‐Performing Aqueous Zinc Ion Battery

A major limitation of MnO₂ in aqueous Zn/MnO₂ ion battery applications is the poor utilization of its electrochemical active surface area. Herein, it is shown that by generating oxygen vacancies (V_O) in the MnO₂ lattice, Gibbs free energy of Zn²⁺ adsorption in the vicinity of V_O can be reduced to thermoneutral value (≈0.05 eV). This suggests that Zn²⁺ adsorption/desorption process on oxygen‐deficient MnO₂ is more reversible as compared to pristine MnO₂. In addition, because of the fact that fewer electrons are needed for Zn? O bonding in oxygen‐deficient MnO₂, more valence electrons can be contributed into the delocalized electron cloud of the material, which aids in enhancing the attainable capacity. As a result, the stable Zn/oxygen‐deficient MnO₂ battery is able to deliver one of the highest capacities of 345 mAh g^?1 reported for a birnessite MnO₂ system. This excellent electrochemical performance suggests that generating oxygen vacancies in MnO₂ may aid in the future development of advanced cathodes for aqueous Zn ion batteries.     

Effects of Metal Ions on the Conformation and Activity of Acutolysin D from Agkistrodon Acutus Venom

Acutolysin D, isolated from the venom of Agkistrodon acutus, possesses marked haemorrhagic and proteolytic activities. The molecular weight and the absorption coefficients (A ^1% ₂₈₀) of acutolyisn D have been determined to be 47,850 ± 8 amu and 9.3 by mass spectrometer and UV spectrum, respectively. The effects of metal ions on the conformation and activity of acutolysin D have been studied by following fluorescence, circular dichroism and biological activity measurements. Acutolysin D contains two Ca²⁺-binding sites and two Zn²⁺-binding sites determined by atomic absorption spectrophotometer. Zn²⁺ is essential for the enzyme activities of acutolysin D, however, the presence of 1 mM Zn²⁺ significantly decreases its caseinolytic activity and intrinsic fluorescence intensity at pH 9.0 due to Zn(OH)₂ precipitate formation. Ca²⁺ is important for the structural integrity of acutolysin D, and the presence of 1 mM Ca²⁺ markedly enhances its caseinolytic activity. Interestingly, the caseinolytic activity which is inhibited partly by Cu²⁺, Co²⁺, Mn²⁺ or Tb³⁺ and inhibited completely by Cd²⁺, is enhanced by Mg²⁺. The fluorescence intensity of the protein decreases in the presence of Cu²⁺, Co²⁺, Cd²⁺ or Mn²⁺, but neither for Ca²⁺, Mg²⁺ nor for Tb³⁺. Zn²⁺, Ca²⁺, Mg²⁺, Cu²⁺, Mn²⁺, Co²⁺ and Tb³⁺ have slight effects on its secondary structure contents. In addition, Cd²⁺ causes a marked increase of antiparallel β-sheet content from 45.5% to 60.2%.     

Role of calcium and calmodulin antagonist in photosynthesis and salinity tolerance inChlorella vulgaris

To cast light upon the role of Ca¹⁺ and calmodulin on photosynthetic rate (P_n), dark respiration (R_D) and amino acid and protein contents in salinity stressed and non-stressedChlorella cultures, the Ca²⁺ chelator EGTA [ethylene glycol-bis-(2-aminoethyl ether)-N,N- tetraacetate] and the calmodulin antagonist TFP (trifluperazine) were used. TFP markedly inhibited P_N while EGTA exerted a slight, if any, effect on P_N. NaCl tolerance, on the other side, was markedly abolished by TFP that inhibited P_N and lowered rate of proline accumulation. Calmodulin might be involved in osmoregulation and salt tolerance ofChlorella. R_D, however, was markedly enhanced by EGTA and Ca²⁺-free medium and hence the Ca²⁺ deprivation increased stress severity exerted by NaCl. Combinations of Na⁺ and Ca²⁺ enhanced P_N, decreased R_D and proline content in comparison with an osmotically equivalent reference culture containing only NaCl. Addition of Ca²⁺ to TFP treated cultures failed to reactivate calmodulin for proline synthesis. However, when Ca²⁺ was added to EGTA-treated cultures, only relatively reduced proline contents were recorded.     

Characteristics of extracellular proteases produced by Bacillus laterosporus and Flavobacterium sp. isolated from gelatinfactory effluents

Forty bacterial isolates from the effluents of a gelatin factory (Jabalpur, India) were screened for protease activity and the two most potent producers were identified as Bacillus laterosporus and a Flavobacterium sp. The enzymes of both isolates were optimal at pH 8 and 60°C, with maximum activity after 90 min. The enzyme activity of B. laterosporus was suppressed by Fe²⁺, Mg²⁺, Mn²⁺ and Zn²⁺ ions but was enhanced by Ba²⁺ and Ca²⁺. That of Flavobacterium sp. was suppressed by Mg²⁺ and Mn²⁺ ions but enhanced by Ba²⁺, Ca²⁺ and Fe²⁺. The enzyme activity of the former was strongly inhibited by KCN, whereas that of the latter was only slightly inhibited by 8-hydroxyquinoline.     

Purification and Characterization of Killer Toxin from a Marine Yeast <Emphasis Type="Italic">Pichia anomala</Emphasis> YF07b Against the Pathogenic Yeast in Crab

The molecular mass of the purified killer toxin from the marine killer yeast YF07b was estimated to be 47.0 kDa. The optimal pH and temperature of the purified killer toxin were 4.5 and 40°C, respectively. The toxin was activated by Ca²⁺, K⁺, Na⁺, Mg²⁺, Na⁺, and Co²⁺. However, Fe²⁺, Fe³⁺, Hg²⁺, Cu²⁺, Mn²⁺, Zn²⁺, and Ag⁺ acted as inhibitors in decreasing activity of the toxin. The toxin was strongly inhibited by phenylmethanesulphonyl fluoride (PMSF), iodoacetic acid, ethylenediaminetetraacetic acid, and 1,10-phenanthroline. The Km of the toxin for laminarin was 1.17 g L⁻¹. The toxin also actively hydrolyzed laminarin and killed the whole cells of the pathogenic yeast in crab.     

Biochemical characterization and sequence analysis of a xylanase produced by an exo-symbiotic bacterium of <Emphasis Type="Italic">Gryllotalpa orientalis</Emphasis>, <Emphasis Type="Italic">Cellulosimicrobium</Emphasis> sp. HY-12

An exo-symbiotic bacterium capable of hydrolyzing xylan was isolated from the gut of the mole cricket, Gryllotalpa orientalis, and identified as Cellulosimicrobium sp. HY-12. The xylanase (XylA _CspHY-12) of this organism bound tightly to both DEAE and mono Q resins, and its molecular mass (M _r) was about 39.0 kDa. The highest xylanase activity was observed at pH 6.0 and 60°C. The enzyme was greatly suppressed by Ca²⁺, Cu²⁺, Co²⁺, and Fe²⁺ ions but not by Mg²⁺ and Mn²⁺. Although XylA _CspHY-12 was capable of hydrolyzing various types of xylosic compounds, it could not decompose carboxymethyl cellulose or xylobiose. The xylA _CspHY-12 gene consisted of an 1,188 bp open reading frame that encoded a polypeptide of 395 amino acids with a deduced molecular mass of 42,925 Da. The domain structure of XylA _CspHY-12 was most similar to those of the glycoside hydrolase (GH) family 10 endoxylanases. However its sequence identity with any of the enzymes in this family was below 52%. The results of this study suggest that the XylA _CspHY-12 is a new cellulase-free endo-β-1,4-xylanase with some properties that are distinct from those of GH family 10.     

Calcium protects <Emphasis Type="Italic">Trifolium repens</Emphasis> L. seedlings against cadmium stress

The effect of calcium (Ca²⁺) on Trifolium repens L. seedlings subjected to cadmium (Cd²⁺) stress was studied by investigating plant growth and changes in activity of antioxidative enzymes. Physiological analysis was carried out on seedlings cultured for 2 weeks on half-strength Hoagland medium with Cd²⁺ concentrations of 0, 400 and 600 μM, and on corresponding medium supplied with CaCl₂ (5 mM). Exposure to increasing Cd²⁺ reduced the fresh weight of the upper part (stems + leaves) of the seedlings more strongly than that of the root system. In both parts of T. repens seedlings H₂O₂ level and lipid peroxidation increased. In the upper part, Cd²⁺ exposure led to a significant decrease in the activity of superoxide dismutase, catalase and glutathione peroxidase and an increase in ascorbate peroxidase activity. In contrast, the roots showed an increase in the activity of antioxidative enzymes under Cd²⁺ stress. Ca²⁺ addition to medium reduced the Cd²⁺ accumulation, and considerably reversed the Cd²⁺-induced decrease in fresh mass as well as the changes in lipid peroxidation in the both parts of T. repens seedlings. Ca²⁺ application diminished the Cd²⁺ effect on the activity of antioxidative enzymes in the upper part, even though it did not significantly affect these enzymes in the roots. So the possible mechanisms for the action of Ca²⁺ in Cd²⁺ stress were considered to reduce Cd²⁺ accumulation, alleviate lipid peroxidation and promote activity of antioxidative enzymes.     

Production and characterization of extracellular protease of mutant Aspergillus niger AB100 grown on fish scale

Fish scale, the chief waste material of fish processing industries was processed and tested for production of extracellular protease by mutant Aspergillus niger AB₁₀₀. Protease production by A. niger AB₁₀₀ was greatly enhanced in presence of processed fish scale powder. Where as among the three complex nutrients tested, soya bean meal shows maximum stimulatory effect over protease production (2,776 μmol/ml/min) when used in combination with glucose (5% w/v) and urea (2.5% w/v). The protease was optimally active at pH 7.0, retaining more than 60% of its activity in the pH range of 5–9. The enzyme was found to be most active at 50°C and stable at 30°C for 1 h. Purification of enzyme by CM-Cellulose and SDS-PAGE resulted in about 26-fold increase in the specific activity of the enzyme with a molecular weight of 30.9 kDa. HPLC study shows the purity of the enzyme as 75.92%. By the activating effect of divalent cations (Fe²⁺, Zn²⁺, Mn²⁺, Ca²⁺and Mg²⁺) and inhibiting effect of chelating agent (EDTA) and Hg²⁺, the enzyme was found to be a metalloprotease.     

Effects of divalent metal cations on lovastatin biosynthesis from <Emphasis Type="Italic">Aspergillus terreus</Emphasis> in chemically defined medium

Effects of six divalent metal cations: Fe²⁺, Ca²⁺, Zn²⁺, Mg²⁺, Cu²⁺and Mn²⁺ on fungal cell growth and lovastatin biosynthesis were investigated by submerged cultivation of Aspergillus terreus in a modified chemically defined medium. The influences of different initial concentrations of the above six metal cations were also examined at 1, 2, and 5 mM, respectively. Cu²⁺ apparently inhibited the cell growth, but had no influence on biosynthesis of lovastatin. All of Fe²⁺, Ca²⁺, Zn²⁺, Mg²⁺ and Mn²⁺ promoted the cell growth and lovastatin biosynthesis in different extents. The highest biomass of 13.8 ± 0.5 g l⁻¹ and specific lovastatin titres of 49.2 ± 1.4 mg gDCW⁻¹ were obtained at the level of 2 and 5 mM in the presence of Zn²⁺, respectively. The values were improved double and 14.4-fold. Excess Zn²⁺ inhibited the cell growth, but enhanced lovastatin biosynthesis with an increment of 17.6 mg l⁻¹ per mM. The interactions of all metal cations slightly inhibited the lovastatin production comparing with the existence of Zn²⁺, Fe²⁺ and Mg²⁺ solely, yet remarkably improved the cell growth. These results suggest that the divalent metal ions Zn²⁺ or Fe²⁺ influence the production by regulating the action of key enzymes such as LovD or LovF in lovastatin biosynthesis.     

钒钛磁铁尾矿土壤中水黄皮根瘤菌铁耐受性与钝化能力研究

铁是好氧微生物生长所必需的元素,而铁污染土壤环境中的根瘤菌是否对高浓度铁具有耐受性和钝化能力尚不清楚。以攀枝花钒钛磁铁尾矿土壤作为基质进行水黄皮共生根瘤菌捕获实验,获得水黄皮共生根瘤并从中分离纯化出根瘤菌39株。通过Fe~(2+)/Fe~(3+)耐受性和钝化能力测试筛选出耐受性和钝化能力均强的优势菌株PZHS20、PZHS90、PZHS87,其对Fe~(2+)的最大耐受质量浓度为1 600 mg/L,其中PZHS20在200 mg/L Fe~(2+)溶液中钝化效率最大,为73.54%;PZHS90对Fe~(3+)的最大耐受质量浓度为1 600 mg/L,而PZHS20和PZHS87对Fe~(3+)的最大耐受质量浓度为1 800 mg/L,其在200 mg/L Fe~(3+)溶液中钝化效率分别为84.25%和81.95%。16S rRNA基因系统进化分析将PZHS20鉴定为苍白杆菌(Ochrobactrum),将PZHS90和PZHS87鉴定为慢生根瘤菌(Bradyrhizobium)。研究结果表明,钒钛磁铁尾矿土壤中的水黄皮根瘤菌具有不同程度的Fe~(2+)/Fe~(3+)耐受性和钝化能力,筛选出的优势菌株为进一步利用水黄皮-根瘤菌联合修复高浓度铁污染土壤提供可利用的菌株资源。