共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of Fermentation and Bioengineering》1995,79(3):290-293
The moderately thermophilic iron-oxidizing bacterium strain TI-1, which lacks enzyme systems involved in CO2 fixation, grows at 45°C in Fe2+ medium supplemented with yeast extract to give a maximum cell growth of 1.0 × 108 cells per ml, but does not grow in Fe2+ medium without yeast extract. To elucidate the physiology of the strain, a synthetic medium was developed. It was found that the best synthetic medium was Fe2+-6AA, containing Fe2+, salts, and the following six l-amino acids: alanine, aspartic acid, glutamic acid, arginine, serine, and histidine. In this medium, strain TI-1 showed a maximum cell growth of 10 × 108 cells/ml. The six amino acids in the Fe2+-6AA medium were used not only as a carbon source but also as a source of nitrogen. Inorganic nitrogen sources, such as ammonium ion, hydrazine, hydroxylamine, nitrite, and nitrate, were not used as a sole source of nitrogen, but rather strongly inhibited the utilization of the six amino acids at 1 mM. In the Fe2+ (10 mM)-6AA medium supplemented with 21 mM Fe3+, reduction of Fe3+ to Fe2+ that was dependent on the added amino acids was observed, suggesting another role of the amino acids in the growth of strain TI-1. Washed, intact cells of strain TI-1 had the activity to reduce Fe3+ to Fe2+. 相似文献
2.
Urszula Guzik Katarzyna Hupert-Kocurek Karina Sałek Danuta Wojcieszyńska 《World journal of microbiology & biotechnology》2013,29(2):267-273
The aim of this paper was to describe the effect of various metal ions on the activity of protocatechuate 3,4-dioxygenase from Stenotrophomonas maltophilia KB2. We also compared activity of different dioxygenases isolated from this strain, in the presence of metal ions, after induction by various aromatic compounds. S. maltophilia KB2 degraded 13 mM 3,4-dihydroxybenzoate, 10 mM benzoic acid and 12 mM phenol within 24 h of incubation. In the presence of dihydroxybenzoate and benzoate, the activity of protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase was observed. Although Fe3+, Cu2+, Zn2+, Co2+, Al3+, Cd2+, Ni2+ and Mn2+ ions caused 20–80 % inhibition of protocatechuate 3,4-dioxygenase activity, the above-mentioned metal ions (with the exception of Ni2+) inhibited catechol 1,2-dioxygenase to a lesser extent or even activate the enzyme. Retaining activity of at least one of three dioxygenases from strain KB2 in the presence of metal ions makes it an ideal bacterium for bioremediation of contaminated areas. 相似文献
3.
Nilanjan Chakraborty Manjushree Chatterjee Gouranga M. Sarkar Sujit Chandra Lahiri 《Bioenergy Research》2010,3(4):314-320
The effect of divalent metal ions on biomethanation was studied using pre-reduced methanogenic AC21 medium in absence or in presence of leaf or root extracts of Eichornia grassipes (water hyacinth) in vitro. The metal ions like Cu2+, Fe2+, Ni2+, and Co2+ were found to be effective in increasing methane production in vitro at low concentrations, but toxic inhibitory effects were observed at relatively high concentrations. Zn2+ ion was inhibitory in character with exceptions. The bioavailability of metal ions in AC21 medium alone or with juices from leaf or root extracts of plant (water hyacinth in the present case) was limited due to complex formation of metal ions with different constituents in the medium, precipitation, etc. However, the results of the microscopic experiments (in vials) with metal ions for methane production by isolated methanogens in the methanogenic medium should not be compared with the conversion of biomass to methane in biodigesters. In such cases, not only a large number of methanogenic bacteria of different strains but also a consortium of bacteria of different specificities is usually involved. Though the biomass may contain sufficient concentrations of metal ions, it is advisable to add metal ions like Cu2+, Fe2+ , Zn 2+ ,Co2+, etc. in the biomass, but the concentrations of the metal ions should be limited to 10–20 µM of the biomass to make methane generation successful. 相似文献
4.
Swati Srivastava Narender Kumar Rajani Salunke Thakur Partha Roy 《Biological trace element research》2013,152(1):135-142
In recent time, vanadium compounds are being used as antidiabetic drug and in orthopedic implants. However, the exact role of this incorporated vanadium in improving the quality of bone structure and morphology is not known. The impact of vanadium ion was studied and compared to other trace metal ions with respect to the proliferation and osteoblast differentiation of C3H10t1/2 cells. Toxicity profile of these trace metal ions revealed a descending toxicity trend of Fe2+ > Zn2+ > Cu2+ > Co2+ > Mn2+ > V5+ > Cr2+. The effect of vanadium and other trace metal ions on osteoblast differentiation was evaluated by culturing the cells for 10 days in osteoblastic medium supplemented with different trace ions at concentrations lower than their cytotoxic doses. The results indicated that vanadium has maximum impact on the induction of osteoblast differentiation by upregulating alkaline phosphatase activity and mineralization by up to 145 and 150 %, respectively (p?<?0.05), over control. Cu2+ and Zn2+ had a mild inhibitory effect, while Mn2+, Fe2+, and Co2+ demonstrated a clear decrease in osteoblast differentiation when compared to the control. The data as presented here demonstrate that orthopedic implants, if supplemented with trace metals like vanadium, may provide a source of better model for bone formation and its turnover. 相似文献
5.
Nucleotide pyrophosphatase from yeast was inhibited by thiols, o-phenanthroline, 8-hydroxyquinoline, EDTA, and 8-hydroxyquinoline-5-sulfonic acid. The inhibition by chelating agents was time and concentration dependent. Inhibition by EDTA was decreased by complexing the EDTA with metal ions before addition to the enzyme. The effectiveness of the metal ions in preventing inhibition by EDTA paralleled the stability constants of the EDTA-metal complexes. Partial recovery of EDTA-inhibited enzyme activity was achieved with Zn2+, Co2+, Fe2+, and Mn2+. Analyses for zinc in the purified enzyme by atomic absorption spectroscopy and by titration with 8-hydroxyquinoline-5-sulfonic acid revealed the presence of approximately 1 g atom/mol of enzyme (Mr 65,000). The data indicate that yeast nucleotide pyrophosphatase is a metalloenzyme in which the zinc plays some role in activity. 相似文献
6.
This report demonstrates that transition metal ions and selenite affect the arsenite methylation by the recombinant human arsenic (+3 oxidation state) methyltransferase (hAS3MT) in vitro. Co2+, Mn2+, and Zn2+ inhibited the arsenite methylation by hAS3MT in a concentration-dependent manner and the kinetics indicated Co2+ and Mn2+ to be mixed (competitive and non-competitive) inhibitors while Zn2+ to be a competitive inhibitor. However, only a high concentration of Fe2+ could restrain the methylation. UV-visible, CD and fluorescence spectroscopy were used to study the interactions between the metal ions above and hAS3MT. Further studies showed that neither superoxide anion nor hydrogen peroxide was involved in the transition metal ion or selenite inhibition of hAS3MT activity. The inhibition of arsenite methylating activity of hAS3MT by selenite was reversed by 2 mM DTT (dithiothreitol) but neither by cysteine nor by β-mercaptoethanol. Whereas, besides DTT, cysteine can also prevent the inhibition of hAS3MT activity by Co2+, Mn2+, and Zn2+. Free Cys residues were involved in the interactions of transition metal ions or selenite with hAS3MT. It is proposed that the inhibitory effect of the ions (Co2+, Mn2+, and Zn2+) or selenite on hAS3MT activity might be via the interactions of them with free Cys residues in hAS3MT to form inactive protein adducts. 相似文献
7.
At 10 mM, Cu+ was highly protective against killing of spores of Bacillus megaterium ATCC 19213 by H2O2, while at higher concentrations, from 15–100 mM, killing was augmented. In contrast, Cu2+, Fe2+, Fe3+, Co2+ or Co3+ ions acted only protectively. Cu+ itself was sporicidal in the absence of H2O2 or ascorbate, and its sporicidal action did not depend on generation of highly reactive oxygen species. It appeared that
killing involved either inhibition of germination or copper toxicity to germinated cells in that Cu+-inactivated spores did not germinate readily but chemical decoating of the cells prior to plating on a solid medium resulted
in reversal of the sporicidal effect.
Received 12 July 1996/ Accepted in revised form 03 November 1996 相似文献
8.
Brittany D. Bennett Evan D. Brutinel Jeffrey A. Gralnick 《Applied and environmental microbiology》2015,81(22):7938-7944
Shewanella oneidensis strain MR-1 is a dissimilatory metal-reducing bacterium frequently found in aquatic sediments. In the absence of oxygen, S. oneidensis can respire extracellular, insoluble oxidized metals, such as iron (hydr)oxides, making it intimately involved in environmental metal and nutrient cycling. The reduction of ferric iron (Fe3+) results in the production of ferrous iron (Fe2+) ions, which remain soluble under certain conditions and are toxic to cells at higher concentrations. We have identified an inner membrane protein in S. oneidensis, encoded by the gene SO_4475 and here called FeoE, which is important for survival during anaerobic iron respiration. FeoE, a member of the cation diffusion facilitator (CDF) protein family, functions to export excess Fe2+ from the MR-1 cytoplasm. Mutants lacking feoE exhibit an increased sensitivity to Fe2+. The export function of FeoE is specific for Fe2+, as an feoE mutant is equally sensitive to other metal ions known to be substrates of other CDF proteins (Cd2+, Co2+, Cu2+, Mn2+, Ni2+, or Zn2+). The substrate specificity of FeoE differs from that of FieF, the Escherichia coli homolog of FeoE, which has been reported to be a Cd2+/Zn2+ or Fe2+/Zn2+ exporter. A complemented feoE mutant has an increased growth rate in the presence of excess Fe2+ compared to that of the ΔfeoE mutant complemented with fieF. It is possible that FeoE has evolved to become an efficient and specific Fe2+ exporter in response to the high levels of iron often present in the types of environmental niches in which Shewanella species can be found. 相似文献
9.
Chastukhina I. B. Sharipova M. R. Gabdrakhmanova L. A. Balaban N. P. Safina D. R. Kostrov S. V. Rudenskaya G. N. Leshchinskaya I. B. 《Microbiology》2004,73(3):279-285
The growth of the recombinant Bacillus subtilis strain AJ73 carrying the Bacillus intermedius 3-19 glutamyl endopeptidase gene on a multicopy plasmid and the effect of some nutrients on the efficiency of extracellular glutamyl endopeptidase production in the stationary growth phase were studied. In this phase, the concentration of glutamyl endopeptidase in the culture liquid peaked at the 48th and 78th hours of cultivation and depended on the composition of the cultivation medium. Unlike the synthesis of glutamyl endopeptidase in the trophophase (i.e., during vegetative growth), which was suppressed by glucose, the synthesis of this enzyme during sporulation was resistant to glucose present in the cultivation medium. A multifactorial experimental design allowed optimal proportions between the concentrations of major nutrients (peptone and inorganic phosphate) to be determined. Inorganic phosphate and ammonium ions augmented the production of glutamyl endopeptidase by 30–150%, and complex organic substrates, such as casein and gelatin, enhanced the production of glutamyl endopeptidase by 50–100%. During sporulation, the production of glutamyl endopeptidase was stimulated by some bivalent cations (Ca2+, Mg2+, and Co2+) and inhibited by others (Zn2+, Fe2+, and Cu2+). The inference is drawn that the regulatory mechanisms of glutamyl endopeptidase synthesis during vegetative growth and sporulation are different. 相似文献
10.
The toxic effect of the Fe2+ and Fe3+ ions on the luminescent recombinant Escherichia coli strain with the luxCDABE operon was studied in short- and long-term experiments. At 30-min exposure of bacteria to the iron ions, the effective concentrations of Fe2+ and Fe3+ resulting in acute toxicity (EC50) were 8.5 and 1.3 mg/L, respectively. In the long-term (24 h) experiment, during active bacterial growth, the toxicity index for Fe2+ and Fe3+ was 65.5 and 62.8, respectively. Addition of the iron ions into the medium did not suppress growth, although it inhibited luminescence. Comparative analysis of the short- and long-term experiments made it possible to assess iron toxicity at the concentrations from 0.5 to 20 mg/L (as calculated for the Fe2+ and Fe3+ ions). Iron ions were found to affect only the reactions that were not vitally important for the cell. At the same time, they had no negative effect on the genetic mechanisms and protein synthesis, thus indicating non-specific toxicity of Fe2+ and Fe3+. 相似文献
11.
Uptake and degradation of EDTA by Escherichia coli 总被引:1,自引:0,他引:1
It was found that Escherichia coli exhibited a growth by utilization of Fe(III)EDTA as a sole nitrogen source. No significant growth was detected when Fe(III)EDTA
was replaced by EDTA complexes with other metal ions such as Ca2+, Co2+, Cu2+, Mg2+, Mn2+, and Zn2+. When EDTA uptake was measured in the presence of various ions, it was remarkable only when Fe3+ was present. The cell extract of E. coli exhibited a significant degradation of EDTA only in the presence of Fe3+. It is likely that the capability of E. coli for the growth by utilization of Fe(III)EDTA results from the Fe3+-dependent uptake and degradation of EDTA. 相似文献
12.
Extracts of Rhodopseudomonas spheroides contain two ferrochelatases: one is soluble and forms metalloporphyrins from deuteroporphyrin and haematoporphyrin; the other is particulate and forms metalloporphyrins from protoporphyrin, mesoporphyrin, deuteroporphyrin and haematoporphyrin. Neither enzyme incorporates Mg2+ into porphyrins or Fe2+ into porphyrin cytochrome c. By using the particulate enzyme, plots of 1/v versus 1/s when one substrate was varied and the other kept constant showed that neither substrate affected the Km of the other. The suggested sequential mechanism for the reaction is supported by derivative plots of slopes and intercepts. The Km for deuteroporphyrin was 21.3μm and that for Co2+ was 6.13μm. The enzyme incorporated Co2+, Fe2+, Zn2+, Ni2+ and Mn2+; Cd2+ was not incorporated and was an inhibitor, competitive with respect to Co2+, non-competitive with respect to deuteroporphyrin. The Ki for Cd2+ was 0.73μm. Ferrochelatase was inhibited by protohaem, non-competitively with respect to Co2+ or with respect to deuteroporphyrin. Inhibition by magnesium protoporphyrin was non-competitive with respect to deuteroporphyrin, uncompetitive with respect to Co2+. The inhibitory concentrations of the metalloporphyrins are lower than those required for the inhibition of δ-aminolaevulate synthetase by protohaem. Fe2+ is not incorporated aerobically into porphyrins unless an electron donor, succinate or NADH, is supplied; the low aerobic rate of metalloporphyrin synthesis obtained is insensitive to rotenone and antimycin. The rate of Fe3+ incorporation increases as anaerobic conditions are achieved. 相似文献
13.
《Process Biochemistry》2007,42(1):40-45
In this work, optimizing trace element composition was attempted as a primary strategy to improve surfactin production from Bacillus subtilis ATCC 21332. Statistical experimental design (Taguchi method) was applied for the purpose of identifying optimal trace element composition in the medium. Of the five trace elements examined, Mg2+, K+, Mn2+, and Fe2+ were found to be more significant factors affecting surfactin production by the B. subtilis strain. In the absence of Mg2+ or K+, surfactin yield decreased to 0.4 g/l, which was only 25% of the value obtained from the control run. When Mn2+ and Fe2+ were both absent, the production yield also dropped to ca. 0.6 g/l, approximately one-third of the control value. However, when only one of the two metal ions (Fe2+ or Mn2+) was missing, the B. subtilis ATCC 21332 strain was able to remain over 80% of original surfactin productivity, suggesting that some interactive correlations among the selected metal ions may involve. Taguchi method was thus applied to reveal the interactive effects of Mg2+, K+, Mn2+, Fe2+ on surfactin production. The results show that interaction of Mg2+ and K+ reached significant level. By further optimizing Mg2+ and K+ concentrations in the medium, the surfactin production was boosted to 3.34 g/l, which nearly doubled the yield obtained from the original control. 相似文献
14.
Illing AC Shawki A Cunningham CL Mackenzie B 《The Journal of biological chemistry》2012,287(36):30485-30496
Divalent metal-ion transporter-1 (DMT1) is a H+-coupled metal-ion transporter that plays essential roles in iron homeostasis. DMT1 exhibits reactivity (based on evoked currents) with a broad range of metal ions; however, direct measurement of transport is lacking for many of its potential substrates. We performed a comprehensive substrate-profile analysis for human DMT1 expressed in RNA-injected Xenopus oocytes by using radiotracer assays and the continuous measurement of transport by fluorescence with the metal-sensitive PhenGreen SK fluorophore. We provide validation for the use of PhenGreen SK fluorescence quenching as a reporter of cellular metal-ion uptake. We determined metal-ion selectivity under fixed conditions using the voltage clamp. Radiotracer and continuous measurement of transport by fluorescence assays revealed that DMT1 mediates the transport of several metal ions that were ranked in selectivity by using the ratio Imax/K0.5 (determined from evoked currents at −70 mV): Cd2+ > Fe2+ > Co2+, Mn2+ ≫ Zn2+, Ni2+, VO2+. DMT1 expression did not stimulate the transport of Cr2+, Cr3+, Cu+, Cu2+, Fe3+, Ga3+, Hg2+, or VO+. 55Fe2+ transport was competitively inhibited by Co2+ and Mn2+. Zn2+ only weakly inhibited 55Fe2+ transport. Our data reveal that DMT1 selects Fe2+ over its other physiological substrates and provides a basis for predicting the contribution of DMT1 to intestinal, nasal, and pulmonary absorption of metal ions and their cellular uptake in other tissues. Whereas DMT1 is a likely route of entry for the toxic heavy metal cadmium, and may serve the metabolism of cobalt, manganese, and vanadium, we predict that DMT1 should contribute little if at all to the absorption or uptake of zinc. The conclusion in previous reports that copper is a substrate of DMT1 is not supported. 相似文献
15.
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. 相似文献
16.
17.
Trejo-Tapia G. Jimenez-Aparicio A. Rodriguez-Monroy M. De Jesus-Sanchez A. Gutierrez-Lopez G. 《Plant Cell, Tissue and Organ Culture》2001,67(1):19-23
The effects of six microelements (Cu2+, Mn2+, Fe2+, Mo2+, Zn2+, Co2+) on the production of betalains and the growth of suspension cultures of Beta vulgaris were studied. The increase of Co2+ from 1–5 M resulted in a 60% increment on the production of betalains. A positive effect of this divalent ion was only accomplished when it was added at the beginning of the culture. This was related to a doubling in the specific betalains production rate compared to B5 control medium. No effects on cell growth and ratio of betacyanines to betaxanthines were observed. Mo2+, Fe2+ and Cu2+ presented a positive but less marked effect, while the increase of Mn2+ did not show effects on the production of betalains compared to B5 control medium. 相似文献
18.
Divalent metal ion effects on a mutant histidinol phosphate phosphatase from Salmonella typhimurium 总被引:1,自引:0,他引:1
The effect of divalent metal ions on the activity of a mutant histidinol phosphate phosphatase has been studied. The enzyme was isolated from strain TA387, a mutant of Salmonella typhimurium with a nonsense lesion near the midpoint of the bifunctional hisB gene. Mn2+, Mg2+, Co2+, and Zn2+ shift the optimal pH of phosphatase activity to 6.5 while Be2+ and Ca2+ have no effect on the shape of the pH profile. In the absence of divalent metal ions, the pH optimum is 7.5. Four Me2+ ions, Mn2+, Co2+, Zn2+, and Fe2+ decreased the Km of histidinol phosphate at pH 6.5 from 5.5 mm (without Me2+) to 0.14 mm. Ni2+ and Be2+ increased the Km to 22.2 and 25.0 mm, respectively, and Ca2+ and Mg2+ had an intermediate effect. Changes in maximal velocity were substantially less, only about 2-fold changes being observed. It was shown that the maximal velocity at optimal pH was the same in the absence and presence of Mn2+. Kinetic analysis indicated that there was a rapid equilibrium-ordered addition of Mn2+ to the enzyme before the addition of the substrate, histidinol phosphate. A kimn2+ of 4.3 μm was calculated for the metal ion activation at both pH 6.5 and 7.5. Addition of ethyl-enediaminetetracetate (EDTA) strongly inhibited the phosphatase; inhibition could be reversed by addition of several Me2+ ions, Mg2+ being the most efficient followed by Mn2+. Prolonged incubation with EDTA led to irreversible inactivation. 相似文献
19.
Copper toxicity has been studied in three nickel-resistant strains ofNeurospora crassa (NiR1, NiR2, and NiR3). NiR1 and NiR2, but not NiR3, were two-to threefold more sensitive than the parent wild strain (N. crassa EM 5297a) to Cu2+ on a normal N medium. On a nitrate N medium, Cu2+ was 16-fold more toxic to NiR3 because of reduced synthesis of nitrite reductase; NiR1 and NiR2 were only fivefold more sensitive to Cu2+, and nitrite reductase synthesis was unaffected. Mn2+ reversed Cu2+ toxicity on normal N medium only, in all strains. Fe3+ counteracted Cu2+ toxicity on nitrate N medium also. It was shown that Cu2+ affected Fe3+ utilization for nitrite reductase synthesis in NiR3 only and that in these Ni2+-resistant strains, Fe3+ antagonized effects of Cu2+, but not of other toxic metal ions. 相似文献
20.
《Journal of Fermentation and Bioengineering》1991,71(2):89-92
Adenosine deaminase was induced when the cells of Klebsiella sp. LF 1202 were cultured in the medium containing adenosine as a sole source of carbon and nitrogen. The induction was partially repressed by the addition of ammonium sulfate in the medium. The amount of adenosine deaminase reached approximately 4.6% of the total intracellular soluble proteins. The enzyme was purified approximately 22-fold with a 25% activity yield. The enzyme was a monomer with a molecular weight of 26,000. The optimal activity was obtained at pH 8.0, 37°C, and the Km value for adenosine was 37 μM. Metal ions such as Zn2+, Co2+, Fe2 and Ni+ inhibited the activity of the enzyme. Sulfhydryl blocking agents such as p-chloromercuribenzoate and HgCl2 were also found to be potent inhibitors for adenosine deaminase. 相似文献