scholarly journals Contributions of Microbial “Contact Leaching” to Pyrite Oxidation under Different Controlled Redox Potentials

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 856
Author(s):  
Bingxu Dong ◽  
Yan Jia ◽  
Qiaoyi Tan ◽  
Heyun Sun ◽  
Renman Ruan
Keyword(s):  
Redox Potential ◽  
Dissolution Rate ◽  
Elemental Sulfur ◽  
Microbial Consortium ◽  
Pyrite Oxidation ◽  
Microbial Consortia ◽  
Redox Potentials ◽  
Sulfur Passivation ◽  
Sulfur Oxidizing ◽  
Contact Oxidation

The function of microbial contact leaching to pyrite oxidation was investigated by analyzing the differences of residue morphologies, leaching rates, surface products, and microbial consortia under different conditions in this study. This was achieved by novel equipment that can control the redox potential of the solution and isolate pyrite from microbial contact oxidation. The morphology of residues showed that the corrosions were a little bit severer in the presence of attached microbes under 750 mV and 850 mV (vs. SHE). At 650 mV, the oxidation of pyrite was undetectable even in the presence of attached microbes. The pyrite dissolution rate was higher with attached microbes than that without attached microbes at 750 mV and 850 mV. The elemental sulfur on the surface of pyrite residues with sessile microorganisms was much less than that without attached microbes at 750 mV and 850 mV, showing that sessile acidophiles may accelerate pyrite leaching by reducing the elemental sulfur inhibition. Many more sulfur-oxidizers were found in the sessile microbial consortium which also supported the idea. The results suggest that the microbial “contact leaching” to pyrite oxidation is limited and relies on the elimination of elemental sulfur passivation by attached sulfur-oxidizing microbes rather than the contact oxidation by EPS-Fe.

Control of the Redox Potential by Oxygen Limitation Inhibits Bioleaching of Pyrite

2009 ◽  
Vol 71-73 ◽  
pp. 401-404 ◽  
Author(s):  
Biao Wu ◽  
Jian Kang Wen ◽  
Gui Ying Zhou ◽  
Ren Man Ruan
Keyword(s):  
Redox Potential ◽  
Dissolution Rate ◽  
Oxygen Limitation ◽  
Metal Sulfides ◽  
Electrochemical Studies ◽  
Redox Potentials ◽  
Nitrogen Gas ◽  
Copper Sulfides ◽  
Fe Content ◽  
Constant Potential

Based on the bioleaching mechanism and electrochemical studies of metal sulfides, the dissolution rate of secondary copper sulfides and pyrite are controlled by redox potentials. Experiment on the bioleaching of the secondary copper sulfides under constant potential by sparging with nitrogen gas demonstrated, by analyzing Cu and Fe content of the bioleaching solution and residues, the pyrite and secondary cooper sulfides dissolution rates have large difference in various redox potential. The pyrite and secondary cooper sulfides have good selection when the redox potential controlled between 700mV and 760mV, we can realize the secondary copper sulfides bioleaching process be controlled, then supply theoretical guide for the iron-acid balance during copper bioleaching process.

scholarly journals Role of redox-inactive metals in controlling the redox potential of heterometallic manganese–oxido clusters

2021 ◽  
Author(s):  
Keisuke Saito ◽  
Minesato Nakagawa ◽  
Manoj Mandal ◽  
Hiroshi Ishikita
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Quantum Chemical Calculations ◽  
Catalytic Reaction ◽  
Quantum Chemical ◽  
Ionic Radius ◽  
Redox Potentials ◽  
Oxygen Evolving ◽  
Highest Occupied Molecular Orbitals

AbstractPhotosystem II (PSII) contains Ca2+, which is essential to the oxygen-evolving activity of the catalytic Mn4CaO5 complex. Replacement of Ca2+ with other redox-inactive metals results in a loss/decrease of oxygen-evolving activity. To investigate the role of Ca2+ in this catalytic reaction, we investigate artificial Mn3[M]O2 clusters redox-inactive metals  [M] ([M]  = Mg2+, Ca2+, Zn2+, Sr2+, and Y3+), which were synthesized by Tsui et al. (Nat Chem 5:293, 2013). The experimentally measured redox potentials (Em) of these clusters are best described by the energy of their highest occupied molecular orbitals. Quantum chemical calculations showed that the valence of metals predominantly affects Em(MnIII/IV), whereas the ionic radius of metals affects Em(MnIII/IV) only slightly.

Metagenomics Study To Compare The Taxonomy And Metabolism of a Lignocellulolytic Microbial Consortium Cultured in Different Carbon Conditions

2021 ◽  
Author(s):  
Qinggeer BORJIGIN ◽  
Bizhou ZHANG ◽  
Xiaofang Yu ◽  
Julin Gao ◽  
Xin ZHANG ◽  
...  
Keyword(s):  
Microbial Consortium ◽  
Agricultural Waste ◽  
Taxonomic Diversity ◽  
Taxonomic Composition ◽  
Microbial Consortia ◽  
Rich Diversity ◽  
Cazy Database ◽  
Taxonomic Affiliation ◽  
In Situ Biodegradation

Abstract A lignocellulolytic microbial consortium holds promise for the in situ biodegradation of crop straw and the comprehensive and effective utilization of agricultural waste. In this study, we applied metagenomics technology to comprehensively explore the metabolic functional potential and taxonomic diversity of the microbial consortia CS (cultured on corn stover) and FP (cultured on filter paper).Analyses of the metagenomics taxonomic affiliation data showed considerable differences in the taxonomic composition and functional profile of the microbial consortia CS and FP. The microbial consortia CS primarily contained members from the genera Pseudomonas, Stenotrophomonas, Achromobacter, Dysgonomonas, Flavobacterium and Sphingobacterium, as well as Cellvibrio, Azospirillum, Pseudomonas, Dysgonomonas and Cellulomonas in FP. The COG and KEGG annotation analyses revealed considerable levels of diversity. Further analysis determined that the CS consortium had an increase in the acid and ester metabolism pathways, while carbohydrate metabolism was enriched in the FP consortium. Furthermore, a comparison against the CAZy database showed that the microbial consortia CS and FP contain a rich diversity of lignocellulose degrading families, in which GH5, GH6, GH9, GH10, GH11, GH26, GH42, and GH43 were enriched in the FP consortium, and GH44, GH28, GH2, and GH29 increased in the CS consortium. The degradative mechanism of lignocellulose metabolism by the two microbial consortia is similar, but the annotation of quantity of genes indicated that they are diverse and vary greatly. The lignocellulolytic microbial consortia cultured under different carbon conditions (CS and FP) differed substantially in their composition of the microbial community at the genus level. The changes in functional diversity were accompanied with variation in the composition of microorganisms, many of which are related to the degradation of lignocellulolytic materials. The genera Pseudomonas, Dysgonomonas and Sphingobacterium in CS and the genera Cellvibrio and Pseudomonas in FP exhibited a much wider distribution of lignocellulose degradative ability.

scholarly journals Current Advances in the Biodegradation and Bioconversion of Polyethylene Terephthalate

2021 ◽  
Vol 10 (1) ◽  
pp. 39
Author(s):  
Xinhua Qi ◽  
Wenlong Yan ◽  
Zhibei Cao ◽  
Mingzhu Ding ◽  
Yingjin Yuan
Keyword(s):  
Polyethylene Terephthalate ◽  
Microbial Consortium ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Microbial Consortia ◽  
Plastic Pollution ◽  
One Step ◽  
Complex Polymers ◽  
The One

Polyethylene terephthalate (PET) is a widely used plastic that is polymerized by terephthalic acid (TPA) and ethylene glycol (EG). In recent years, PET biodegradation and bioconversion have become important in solving environmental plastic pollution. More and more PET hydrolases have been discovered and modified, which mainly act on and degrade the ester bond of PET. The monomers, TPA and EG, can be further utilized by microorganisms, entering the tricarboxylic acid cycle (TCA cycle) or being converted into high value chemicals, and finally realizing the biodegradation and bioconversion of PET. Based on synthetic biology and metabolic engineering strategies, this review summarizes the current advances in the modified PET hydrolases, engineered microbial chassis in degrading PET, bioconversion pathways of PET monomers, and artificial microbial consortia in PET biodegradation and bioconversion. Artificial microbial consortium provides novel ideas for the biodegradation and bioconversion of PET or other complex polymers. It is helpful to realize the one-step bioconversion of PET into high value chemicals.

scholarly journals Detecting Redox Potentials Using Porous Boron Nitride/ATP-DNA Aptamer/Methylene Blue Biosensor to Monitor Microbial Activities

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 83
Author(s):  
Kai Guo ◽  
Zirui Song ◽  
Gaoxing Wang ◽  
Chengchun Tang
Keyword(s):  
Methylene Blue ◽  
Microbial Community ◽  
Boron Nitride ◽  
Redox Potential ◽  
Microbial Activity ◽  
Potential Change ◽  
Dna Aptamer ◽  
Redox Potentials ◽  
Microplate Reader

Microbial activity has gained attention because of its impact on the environment and the quality of people’s lives. Most of today’s methods, which include genome sequencing and electrochemistry, are costly and difficult to manage. Our group proposed a method using the redox potential change to detect microbial activity, which is rooted in the concept that metabolic activity can change the redox potential of a microbial community. The redox potential change was captured by a biosensor consisting of porous boron nitride, ATP-DNA aptamer, and methylene blue as the fluorophore. This assembly can switch on or off when there is a redox potential change, and this change leads to a fluorescence change that can be examined using a multipurpose microplate reader. The results show that this biosensor can detect microbial community changes when its composition is changed or toxic metals are ingested.

scholarly journals Organic Stabilization of Extracellular Elemental Sulfur in a Sulfurovum-Rich Biofilm: A New Role for Extracellular Polymeric Substances?

2021 ◽  
Vol 12 ◽  
Author(s):  
Brandi Cron ◽  
Jennifer L. Macalady ◽  
Julie Cosmidis
Keyword(s):  
Crystal Structures ◽  
Extracellular Polymeric Substances ◽  
Elemental Sulfur ◽  
Dense Matrix ◽  
Cave System ◽  
Carboxylic Groups ◽  
Sulfur Oxidizing ◽  
New Evidence ◽  
Sulfur Oxidizing Bacteria

This work shines light on the role of extracellular polymeric substance (EPS) in the formation and preservation of elemental sulfur biominerals produced by sulfur-oxidizing bacteria. We characterized elemental sulfur particles produced within a Sulfurovum-rich biofilm in the Frasassi Cave System (Italy). The particles adopt spherical and bipyramidal morphologies, and display both stable (α-S8) and metastable (β-S8) crystal structures. Elemental sulfur is embedded within a dense matrix of EPS, and the particles are surrounded by organic envelopes rich in amide and carboxylic groups. Organic encapsulation and the presence of metastable crystal structures are consistent with elemental sulfur organomineralization, i.e., the formation and stabilization of elemental sulfur in the presence of organics, a mechanism that has previously been observed in laboratory studies. This research provides new evidence for the important role of microbial EPS in mineral formation in the environment. We hypothesize that the extracellular organics are used by sulfur-oxidizing bacteria for the stabilization of elemental sulfur minerals outside of the cell wall as a store of chemical energy. The stabilization of energy sources (in the form of a solid electron acceptor) in biofilms is a potential new role for microbial EPS that requires further investigation.

Sulfur-oxidizing enzyme of Ferrobacillus ferrooxidans (Thiobacillus ferrooxidans)

1968 ◽  
Vol 46 (5) ◽  
pp. 457-461 ◽  
Author(s):  
Marvin Silver ◽  
D. G. Lundgren
Keyword(s):  
Enzyme Preparation ◽  
Elemental Sulfur ◽  
Thiobacillus Ferrooxidans ◽  
Reduced Glutathione ◽  
Heme Iron ◽  
Ph Optimum ◽  
Non Heme Iron ◽  
Sulfur Oxidizing

The sulfur-oxidizing enzyme was purified about 15-fold from sulfur-grown Ferrobacillus ferrooxidans. The enzyme has a pH optimum of 7.8 and requires both elemental sulfur and reduced glutathione (GSH); however, a glutathione–polysulfide complex could also serve as substrate. The Km for GSH was determined to be 2 × 10−3 M. Non-heme iron and labile sulfide were present in the enzyme preparation, and sulfite was found to be the end product of the reaction.

scholarly journals Temperature-induced diurnal redox potential in soil

2021 ◽  
Author(s):  
Kristof Dorau ◽  
Bianca Bohn ◽  
Lutz Weihermüller ◽  
Tim Mansfeldt
Keyword(s):  
Redox Potential ◽  
Temporal Resolution ◽  
High Temporal Resolution ◽  
Redox Potentials ◽  
Soils And Sediments

With the capabilities to measure redox potentials (EH) at a high temporal resolution, scientists have observed diurnal EH that occur in a distinct periodicity in soils and sediments. These patterns...

Sulfurovum indicum sp. nov., a novel hydrogen- and sulfur-oxidizing chemolithoautotroph isolated from a deep-sea hydrothermal plume in the Northwestern Indian Ocean

2019 ◽  
Vol 71 (3) ◽  
Author(s):  
Shaobin Xie ◽  
Shasha Wang ◽  
Dengfeng Li ◽  
Zongze Shao ◽  
Qiliang Lai ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Deep Sea ◽  
Type Species ◽  
Elemental Sulfur ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Phenotypic Data ◽  
Content Type ◽  
Link Type ◽  
Sulfur Oxidizing

A novel mesophilic, hydrogen-, and sulfur-oxidizing bacterium, designated strain ST-419T, was isolated from a deep-sea hydrothermal vent plume on the Carlsberg Ridge of the Northwestern Indian Ocean. The isolate was a Gram-staining-negative, non-motile and coccoid to oval-shaped bacterium. Growth was observed at 4–50 °C (optimum 37 °C), pH 5.0–8.6 (optimum pH 6.0) and 1.0–5.0 % (w/v) NaCl (optimum 3.0 %). ST-419T could grow chemlithoautotrophically with molecular hydrogen, sulfide, elemental sulfur and thiosulfate as energy sources. Molecular oxygen, nitrate and elemental sulfur could be used as electron acceptors. The predominant fatty acids were C16 : 1ω7c, C18 : 1ω7c and C16 : 0. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The respiratory quinone was menaquinone MK-6 and the G+C content of the genomic DNA was 42.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that ST-419T represented a member of genus Sulfurovum and was most closely related to Sulfurovum riftiae 1812ET, with 97.6 % sequence similarity. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between ST-419T and S. riftiae 1812ET were 74.6 and 19.6 %, respectively. The combined genotypic and phenotypic data indicate that ST-419T represents a novel species within the genus Sulfurovum , for which the name Sulfurovum indicum sp. nov. is proposed. The type strain is ST-419T (=MCCC 1A17954T=KCTC 25164T).

scholarly journals Site-directed mutations in fungal laccase: effect on redox potential, activity and pH profile

1998 ◽  
Vol 334 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Feng XU ◽  
Randy M. BERKA ◽  
Jill A. WAHLEITHNER ◽  
Beth A. NELSON ◽  
Jeffrey R. SHUSTER ◽  
...  
Keyword(s):  
Redox Potential ◽  
Phenol Oxidase ◽  
Ascorbate Oxidase ◽  
Single Mutation ◽  
Redox Potentials ◽  
Wild Type ◽  
Ph Optimum ◽  
Ph Profile ◽  
Potential Activity

A Myceliophthora thermophila laccase and a Rhizoctonia solani laccase were mutated on a pentapeptide segment believed to be near the type-1 Cu site. The mutation L513F in Myceliophthora laccase and the mutation L470F in Rhizoctonia laccase took place at a position corresponding to the type-1 Cu axial methionine (M517) ligand in Zucchini ascorbate oxidase. The triple mutations V509L,S510E,G511A in Myceliophthora laccase and L466V,E467S,A468G in Rhizoctonia laccase involved a sequence segment whose homologue in ascorbate oxidase is flanked by the M517 and a type-1 Cu-ligating histidine (H512). The single mutation did not yield significant changes in the enzymic properties (including any significant increase in the redox potential of the type-1 Cu). In contrast, the triple mutation resulted in several significant changes. In comparison with the wild type, the Rhizoctonia and Myceliophthora laccase triple mutants had a phenol-oxidase activity whose pH optimum shifted 1 unit lower and higher, respectively. Although the redox potentials were not significantly altered, the Km, kcat and fluoride inhibition of the laccases were greatly changed by the mutations. The observed effects are interpreted as possible mutation-induced structural perturbations on the molecular recognition between the reducing substrate and laccase and on the electron transfer from the substrate to the type-1 Cu centre.

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