Pseudomonas Putida Strain MnB1 Research Articles

Biologically Assisted One-Step Synthesis of Electrode Materials for Li-Ion Batteries

Mn(II)-oxidizing organisms promote the biomineralization of manganese oxides with specific textures, under ambient conditions. Controlling the phases formed and their texture on a larger scale may offer environmentally relevant routes to manganese oxide synthesis, with potential technological applications, for example, for energy storage. In the present study, we sought to use biofilms to promote the formation of electroactive minerals and to control the texture of these biominerals down to the electrode scale (i.e., cm scale). We used the bacterium Pseudomonas putida strain MnB1 which can produce manganese oxide in a biofilm. We characterized the biofilm-mineral assembly using a combination of electron microscopy, synchrotron-based X-ray absorption spectroscopy, X-ray diffraction, thermogravimetric analysis and electron paramagnetic resonance spectroscopy. Under optimized conditions of biofilm growth on the surface of current collectors, mineralogical characterizations revealed the formation of several minerals including a slightly crystalline MnOx birnessite. Electrochemical measurements in a half-cell against Li(0) revealed the electrochemical signature of the Mn4+/Mn3+ redox couple indicating the electroactivity of the biomineralized biofilm without any post-synthesis chemical, physical or thermal treatment. These results provide a better understanding of the properties of biomineralized biofilms and their possible use in designing new routes for one-pot electrode synthesis.

Enhanced performance of thallium(I) removal by in situ-generated manganese oxides during biogenic Mn(II) oxidation

Little is known about the reciprocal effect of manganese-oxidizing bacteria (MOB), in situ-generated biogenic manganese oxide (BMO) and thallium (Tl) removal. In this study, the Tl(I) removal characteristics during extracellular BMO formation by Pseudomonas putida strain MnB1 were investigated. BMO with a final maturity of 91.25 % achieved 95.20 % Tl(I) removal during biogenic Mn(II) oxidation. The improvement mechanisms of Tl(I) removal in biological systems were mainly due to the involvement of Mn(III) intermediates and tyrosine and tryptophan protein-like substances from MOB. The addition of exogenous MOB reoxidized the residual Mn2+ to BMO, thus promoting Tl(I) removal. BMO showed a higher adsorption ability for Tl(I) at inner depths owing to its layer stacking structure, and 64.02 % Tl(I) was further oxidized to Tl(III) by highly matured BMO. Surface complexation also played an important role during Tl(I) removal. Moreover, BMO showed good adsorption selectivity for Tl(I) with coexisting Fe(III), Cr(III) and Cd(II). These findings expand existing knowledge on the characteristics of in situ-generated BMO and indicate that BMO has practical application value in Tl(I) decontamination from water.

Efficient removal of 17α-ethinylestradiol from secondary wastewater treatment effluent by a biofilm process incorporating biogenic manganese oxide and Pseudomonas putida strain MnB1

This study proposes a biofilm process to immobilize biogenic manganese oxide (BMO) and Pseudomonas putida MnB1 (BMO-MnB1), which shows excellent synergistic effects for 17α-ethinylestradiol (EE2) from secondary wastewater treatment effluent (WWTE). Modified granular activated carbon (M-GAC) was used as the packing carrier, inoculated with Pseudomonas putida MnB1 and Mn(II) to form the BMO-MnB1 biofilm. Feasibility tests were performed to compare the EE2 removal efficiency with that of the conventional biofilm process (BAC) for heterogeneous microbial communities. Results show that in the BAC, EE2 was removed mainly by adsorption, with biodegradation contributing only slightly to the overall performance. In contrast, the BMO-MnB1 biofilter outperformed the BAC. Furthermore, less than 4% of the total EE2 removed was extracted from the biofilter medium over 150 days of operation, confirming that EE2 was biodegraded by P. putida MnB1 or chemically oxidized by BMO. Our results suggest that BMO-MnB1 biofilm processes have high potential for practical applications in removal of endocrine disrupting compounds from wastewater effluent.

Synergistic effects of biogenic manganese oxide and Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1 on the degradation of 17 α-ethinylestradiol

While biogenic manganese oxide (BMO) generated via the oxidation of Mn(II) by the Mn-oxidizing bacteria (MOB) have received attention, the relative roles of biological activity by MOB themselves were not clearly investigated. In this study, the synergistic effects of BMO and MOB Pseudomonas putida strain MnB1 on the degradation of 17α-ethinylestradiol (EE2) was investigated. Experiments with BMO in the presence of P. putida MnB1 showed 15-fold higher removal than that with BMO alone, suggesting that EE2 degradation was mediated by the biological activity of MOB as well as abiotic reaction by BMO. Trapping experiments with pyrophosphate (PP) proved that Mn(III) intermediate formed during the biological process from Mn (II) to Mn (IV) contribute much to the EE2 removal. Also, sharp decreases in EE2 removal were observed when microbial activity was inactivated by heat treatment or sodium azide. From this study, the EE2 removal mechanisms by BMO in the presence P. putida MnB1 are described as follows: (1) abiotic oxidation of EE2 by BMO occurs. (2) P. putida MnB1 indirectly oxidizes EE2 by transferring electrons from the Mn (III) intermediate. (3) P. putida MnB1 continuously re-oxidizes the Mn(II) released from the oxidative degradation of EE2 by BMO, generating new Mn(III)-intermediates or BMO.

Manganese Removal from Metal Refinery Wastewater Using Mn(II)-Oxidizing Bacteria

There is a growing interest in the use of Mn (II)-oxidizing bacteria to treat Mn-containing metal refinery wastewaters instead of using conventional chemical approaches since the former could reduce the cost of alkaline agents and oxidants to remove Mn (II) as Mn oxides at alkaline pH. The Mn level was found naturally dropped in the industrial metal refinery wastewater treatment system, where the formation of Mn-enriched sludge was apparent. This observation motived us to investigate the possible involvement of microbially mediated reactions. From the sludge sample, Pseudomonas sp. strain SK3 was successfully isolated and tested for its Mn (II)-oxidation characteristics. Strain SK3 completely removed 100 ppm Mn (II) within 42 hours as birnessite ((Na,Ca,K)0.6(MnIV, MnIII)2O4·1.5H2O) under optimized conditions. Copper ions were found to be an important factor in promoting Mn (II) oxidation. Changes in the Mn (IV)/Mn (III) ratio during bacterial Mn (II)-oxidation indicated the involvement of 2-step one-electron transfer reactions in the formation of biogenic birnessite with Mn (III) as intermediate. Characteristics of strain SK3 were compared with those of a well-known Mn (II)-oxidizing bacterium, Pseudomonas putida strain MnB1. Strain SK3 displayed more robust Mn (II) oxidation capabilities under several severe conditions, showing its ideal characteristics for use in the industrial water treatment process.

Enhanced adsorption of heavy metals with biogenic manganese oxide immobilized on zeolite

Although nano-sized Biogenic Manganese Oxide (BMO) provides excellent adsorption capacity, its use in water treatment has been limited because it is too small to be readily separated from treated water. Therefore, this work investigated the feasibility of immobilizing BMO on zeolite (BMO/Zeolite) and the use of this material for heavy metal adsorption. BMO/Zeolite was prepared by incubating Pseudomonas putida strain MnB1 in the presence of Mn2+ and natural zeolite pretreated with NaCl (NaCl-Zeolite). BMO immobilization was confirmed by transmission electron microscopy and energy dispersive X-ray analysis. The maximum BMO loading (BMO/Zeolite) was 17.09 mg/g, and the specific surface area increased as the BMO loading was increased. Isotherms and kinetics studies were performed to evaluate the heavy metal adsorption characteristics. The maximum adsorption capacities of Pb2+, Cd2+, and Zn2+ with the BMO/Zeolite were 36.4-70.5% higher than with the NaCl-Zeolite. The amount of heavy metal adsorption increased with higher pH and temperature and with lower ionic strength. The results from this study demonstrate that immobilized BMO not only promotes heavy metal adsorption.

Effect of exopolymers on oxidative dissolution of natural rhodochrosite by Pseudomonas putida strain MnB1: An electrochemical study

Oxidative dissolution of natural rhodochrosite by the Mn(II) oxidizing bacterium Pseudomonas putida strain MnB1 was investigated based on batch and electrochemical experiments using natural rhodochrosite as the working electrode. Tafel curves and batch experiments revealed that bacterial exopolymers (EPS) significantly increased dissolution of natural rhodochrosite. The corrosion current significantly increased with reaction time for EPS treatment. However, the corrosion process was blocked in the presence of cells plus extra EPS due to formation of the passivation layer. Moreover, the scanning electron microscopy and the energy dispersive spectroscopy (SEM–EDS) results showed that the surface of the natural rhodochrosite was notably changed in the presence of EPS alone or/and bacterial cells. This study is helpful for understanding the role of EPS in bacterially oxidation of Mn(II). It also indicates that the Mn(II) oxidizing bacteria may exert their effects on Mn(II) cycle and other biological and biogeochemical processes much beyond their local ambient environment because of the catalytically dissolution of solid Mn(II) by EPS and the possible long distance transport of the detached EPS.

Heavy metal adsorption with biogenic manganese oxides generated by Pseudomonas putida strain MnB1

Biogenic Mn oxides (BMO) have attracted a great attention recently, due to their high heavy metals adsorption capacity. However, the characteristics of the heavy metals adsorption by BMO have not been explored in depth. In this study, nano-sized and poorly crystalline BMO was generated by Pseudomonas putida MnB1, and the heavy metals adsorption by BMO was investigated based on isotherm and kinetic studies. The adsorption capacities of BMO for Pb(II), Cd(II), and Zn(II) were 7–8 times higher than abiotic Mn oxide (i.e., birnessite). The results of the equilibrium adsorption study using several isotherm models showed that adsorption of Pb(II), Cd(II), and Zn(II) on BMO surfaces is a chemical adsorption. The adsorption of Pb(II) and Zn(II) was homogeneous but that of Cd(II) was heterogeneous, probably due to the contribution of ion exchange. Among three heavy metals, Pb(II) was preferentially adsorbed and the adsorption was faster than others. The adsorption capacity of heavy metals by BMO increased as pH increased and ionic strength decreased. It also increased as the temperature increased, indicating the adsorption is endothermic. The results of this study indicate that BMO is an excellent adsorbent due to the abundant vacancies in its amorphous structure.

Removal of 17α-Ethinylestradiol by Biogenic Manganese Oxides Produced by the Pseudomonas putida strain MnB1

Synthetic and persistent endocrine disrupting chemicals (EDCs) such as 17α-ethinylestradiol (EE2) have been frequently detected in the effluent of wastewater treatment plants and induce hazards to humans and wildlife. In this study, biogenic Mn oxides were tested for the removal of EE2, and factors affecting the reaction were also investigated. The biogenic Mn oxides produced by Pseudomonas putida strain MnB1 were nano-sized and poorly crystallized particles. A concentration of 7.9 mg l−1 biogenic Mn oxides showed 87% EE2 (1 mg l−1) removal efficiency in 2 h, which confirms the excellent potential of biogenic Mn oxides for removal of estrogens. EE2 removal was enhanced at high Mn oxide doses and at low pH. Co-existing heavy metals significantly inhibit EE2 removal, due to their competition for the reactive sites of biogenic Mn oxides. Humic acid (HA) also obstructed EE2 removal, but the adverse effect was alleviated as HA concentration increased, possibly due to the formation of soluble complexes with the released Mn2+, of which adsorption onto Mn oxides reduces surface reactive sites.

Characterization of the Biogenic Manganese Oxides Produced by Pseudomonas putida strain MnB1

Abstract Biogenic Mn oxides are expected to have great potential in the control of water pollution due to their high catalytic activity, al-though information on biological Mn oxidation is not currently sufficient. In this study, the growth of a Mn oxidizing microorganism, Pseudomonas putida MnB1, was examined, with the Mn oxides formed by this strain characterized. The growth of P . putida MnB1 was not significantly influenced by Mn(II), but showed a slightly decreased growth rate in the presence of Pb(II) and EE2, indicating their insignificant adsorption onto the cell surface. Mn oxides were formed by P . putida MnB1, but the liquid growth medium and resulting biogenic solids were poorly crystalline, nano-sized particles. Biogenic Mn oxidation by P . putida MnB1 followed Michaelis-Menten kinetics, with stoichiometric amounts of Mn oxides formed, which corresponded with the initial Mn(II) concentration. However, the formation of Mn oxides was inhibited at high initial Mn(II) concentration, suggesting mass transfer obstruction of Mn(II) due to the ac-cumulation of Mn oxides on the extracellular layer. Mn oxidation by

Characterization of the Manganese Oxide Produced by Pseudomonas Putida Strain MnB1

AbstractFor Abstract see ChemInform Abstract in Full Text.

Reductive Dissolution of Biogenic Manganese Oxides in the Presence of a Hydrated Biofilm

The chemical reactivity of the biogenic Mn oxide produced by Pseudomonas putida strain MnB1 was assessed in the presence of bacterial cells and biofilm through reductive dissolution experiments at pH 4.4, 5.2, and 6.0. The reactivity of the biogenic Mn oxide was compared to that of a synthetic (chemically produced) birnessite at pH 6.0. In addition, the effect of bacterial cells and biofilm on the reactivity of the synthetic birnessite was examined at pH 6.0. One-to-one (1:1) mole per mole reactions between total ascorbic acid species, [asc]TOT, and Mn(IV), and 1:2 mole per mole reactions between [asc]TOT and Mn(III) were proposed to explain the observed deviation from the oxidation-reduction reaction stoichiometry, Mn(IV)O2(s) + [asc]TOT xrArr; Mn(II)(aq) + products. The observed stoichiometry of the oxidation-reduction reactions was consistent with the known average oxidation number of Mn in the synthetic birnessite studied. The average oxidation number of Mn in the biogenic Mn oxide, calculated from the molar ratio of [asc]TOT oxidized to Mn dissolved, was in agreement with previous measurements of Mn average oxidation number (3.91–4.00). The rate coefficient for reductive dissolution of synthetic birnessite was equal to that of the biogenic Mn oxide at pH 6.0. The rate coefficient for reductive dissolution of the biogenic Mn oxide was found to decrease with solution pH. The bacterial cells and biofilm interfered with the net reductive dissolution of synthetic birnessite, perhaps by intercepting the Mn+ 2 (aq) reaction product.

Spatially resolved characterization of biogenic manganese oxide production within a bacterial biofilm.

Pseudomonas putida strain MnB1, a biofilm-forming bacterial culture, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of aqueous Mn+2 [Mn+2(aq)] by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm, using scanning transmission X-ray microscopy (STXM) combined with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Mn L2,3 absorption edges. Subsamples were collected from growth flasks containing 0.1 and 1 mM total Mn at 16, 24, 36, and 48 h after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at a 40-nm resolution. Manganese NEXAFS spectra were extracted from X-ray energy sequences of STXM images (stacks) and fit with linear combinations of well-characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III), and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn+2(aq) was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission X-ray microscopy is a promising tool for advancing the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.

Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium

The possible roles of siderophores (high affinity chelators of iron(III)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVD MnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVD MnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350–600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVD MnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A max = 408–410 nm) different from that of either PVD MnB1-Fe(III) or uncomplexed PVD MnB1. Mn(III) competed strongly with Fe(III) for binding by PVD MnB1 in culture filtrates (pH 8, 4°C). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVD MnB1 complex at a citrate/PVD MnB1 molar ratio of 830 (pH 8, 4°C), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVD MnB1 complex. Most of the PVD MnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVD MnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4°C) for the neutral species MnHPVD MnB1 (log K = 47.5 ± 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVD MnB1 (log K = 44.6 ± 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron.

Characterization of the manganese oxide produced by pseudomonas putida strain MnB1

Manganese oxides form typically in natural aqueous environments via Mn(II) oxidation catalyzed by microorganisms, primarily bacteria, but little is known about the structure of the incipient solid-phase products. The Mn oxide produced by a Pseudomonas species representative of soils and freshwaters was characterized as to composition, average Mn oxidation number, and N 2 specific surface area. Electron microscopy, X-ray diffraction, and X-ray absorption near edge structure spectroscopy were applied to complement the physicochemical data with morphological and structural information. A series of synthetic Mn oxides also was analyzed by the same methods to gain better comparative understanding of the structure of the biogenic oxide. The latter was found to be a poorly crystalline layer type Mn(IV) oxide with hexagonal symmetry, significant negative structural charge arising from cation vacancies, and a relatively small number of randomly stacked octahedral sheets per particle. Its properties were comparable to those of δ-MnO 2 (vernadite) and a poorly crystalline hexagonal birnessite (“acid birnessite”) synthesized by reduction of permanganate with HCl, but they were very different from those of crystalline triclinic birnessite. Overall, the structure and composition of the Mn oxide produced by P. putida were similar to what has been reported for other freshly precipitated Mn oxides in natural weathering environments, yielding further support to the predominance of biological oxidation as the pathway for Mn oxide formation. Despite variations in the degree of sheet stacking and Mn(III) content, all poorly crystalline oxides studied showed hexagonal symmetry. Thus, there is a need to distinguish layer type Mn oxides with structures similar to those of natural birnessites from the synthetic triclinic variety. We propose designating the unit cell symmetry as an addition to the current nomenclature for these minerals.