scholarly journals Bioleaching of Manganese Oxides at Different Oxidation States by Filamentous Fungus Aspergillus niger

2021 ◽  
Vol 7 (10) ◽  
pp. 808
Author(s):  
Bence Farkas ◽  
Marek Bujdoš ◽  
Filip Polák ◽  
Michaela Matulová ◽  
Martin Cesnek ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Filamentous Fungus ◽  
Manganese Oxides ◽  
Culture Medium ◽  
Soil Fungi ◽  
Alternative Pathway ◽  
Manganese Content ◽  
Oxidation States ◽  
Reductive Dissolution ◽  
The Stability

This work aimed to examine the bioleaching of manganese oxides at various oxidation states (MnO, MnO·Mn2O3, Mn2O3 and MnO2) by a strain of the filamentous fungus Aspergillus niger, a frequent soil representative. Our results showed that the fungus effectively disintegrated the crystal structure of selected mineral manganese phases. Thereby, during a 31-day static incubation of oxides in the presence of fungus, manganese was bioextracted into the culture medium and, in some cases, transformed into a new biogenic mineral. The latter resulted from the precipitation of extracted manganese with biogenic oxalate. The Mn(II,III)-oxide was the most susceptible to fungal biodeterioration, and up to 26% of the manganese content in oxide was extracted by the fungus into the medium. The detected variabilities in biogenic oxalate and gluconate accumulation in the medium are also discussed regarding the fungal sensitivity to manganese. These suggest an alternative pathway of manganese oxides’ biodeterioration via a reductive dissolution. There, the oxalate metabolites are consumed as the reductive agents. Our results highlight the significance of fungal activity in manganese mobilization and transformation. The soil fungi should be considered an important geoactive agent that affects the stability of natural geochemical barriers.

scholarly journals Aspergillus niger Decreases Bioavailability of Arsenic(V) via Biotransformation of Manganese Oxide into Biogenic Oxalate Minerals

2020 ◽  
Vol 6 (4) ◽  
pp. 270
Author(s):  
Bence Farkas ◽  
Marek Kolenčík ◽  
Miroslav Hain ◽  
Edmund Dobročka ◽  
Gabriela Kratošová ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Manganese Oxide ◽  
Manganese Oxides ◽  
Culture Medium ◽  
Arsenic Content ◽  
Manganese Ions ◽  
Potentially Toxic Metals ◽  
Ability To Act ◽  
Static Cultivation ◽  
The Stability

The aim of this work was to evaluate the transformation of manganese oxide (hausmannite) by microscopic filamentous fungus Aspergillus niger and the effects of the transformation on mobility and bioavailability of arsenic. Our results showed that the A. niger strain CBS 140837 greatly affected the stability of hausmannite and induced its transformation into biogenic crystals of manganese oxalates—falottaite and lindbergite. The transformation was enabled by fungal acidolysis of hausmannite and subsequent release of manganese ions into the culture medium. While almost 45% of manganese was bioextracted, the arsenic content in manganese precipitates increased throughout the 25-day static cultivation of fungus. This significantly decreased the bioavailability of arsenic for the fungus. These results highlight the unique A. niger strain’s ability to act as an active geochemical factor via its ability to acidify its environment and to induce formation of biogenic minerals. This affects not only the manganese speciation, but also bioaccumulation of potentially toxic metals and metalloids associated with manganese oxides, including arsenic.

scholarly journals Fungal Mobilization of Selenium in the Presence of Hausmannite and Ferric Oxyhydroxides

2021 ◽  
Vol 7 (10) ◽  
pp. 810
Author(s):  
Bence Farkas ◽  
Hana Vojtková ◽  
Marek Bujdoš ◽  
Marek Kolenčík ◽  
Martin Šebesta ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Adverse Effects ◽  
Filamentous Fungus ◽  
Manganese Oxides ◽  
Fungal Growth ◽  
Soil Fungus ◽  
Mineral Phases ◽  
Manganese Uptake ◽  
Solid Phases ◽  
Iron And Manganese

Bioleaching of mineral phases plays a crucial role in the mobility and availability of various elements, including selenium. Therefore, the leachability of selenium associated with the surfaces of ferric and manganese oxides and oxyhydroxides, the prevailing components of natural geochemical barriers, has been studied in the presence of filamentous fungus. Both geoactive phases were exposed to selenate and subsequently to growing fungus Aspergillus niger for three weeks. This common soil fungus has shown exceptional ability to alter the distribution and mobility of selenium in the presence of both solid phases. The fungus initiated the extensive bioextraction of selenium from the surfaces of amorphous ferric oxyhydroxides, while the hausmannite (Mn3O4) was highly susceptible to biodeterioration in the presence of selenium. This resulted in specific outcomes regarding the selenium, iron, and manganese uptake by fungus and residual selenium concentrations in mineral phases as well. The adverse effects of bioleaching on fungal growth are also discussed.

scholarly journals On the manganese content of transplanted tumours

1913 ◽  
Vol 86 (586) ◽  
pp. 174-179 ◽  
Keyword(s):  
Aspergillus Niger ◽  
Culture Medium ◽  
Manganese Content ◽  
Biological Significance ◽  
Biological Properties ◽  
Animal Tissues ◽  
Quantitative Distribution ◽  
Close Relationship ◽  
The Subject ◽  
Points Of View

The occurrence of manganese in plants is well known. Its quantitative distribution and biological significance have been carefully studied from many points of view. A few examples of the more recent, especially experimental work, illustrating some of the biological properties of this metal, may be mentioned. Bertrand showed that there exists a close relationship between the activity of vegetable oxydases and the amount of manganese present. In a series of very exact experiments with Aspergillus niger , the same author demonstrated that the presence of manganese is necessary to the formation of conidia of this mould, and also that the rapidity of its growth may be largely influenced by the quantity of manganese added to the culture medium. The study of manganese in animals is far less advanced than in plants. Since the food-stuffs contain manganese, it is obvious that this element is continuously introduced into the animal body. The detection of manganese in animal tissues has been the subject of repeated investigation during the last 70 years. The conclusions, however, which the earlier authors have drawn are very contradictory, undoubtedly attributable mainly to the insufficiency and the defects of the methods and the technic used for the detection and estimation of this element.

scholarly journals Characterization and optimization of extracellular enzymes production by Aspergillus niger strains isolated from date by-products

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Reda Bellaouchi ◽  
Houssam Abouloifa ◽  
Yahya Rokni ◽  
Amina Hasnaoui ◽  
Nabil Ghabbour ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Culture Medium ◽  
Extracellular Enzymes ◽  
Enzyme Expression ◽  
Specific Enzyme ◽  
Enzymatic Production ◽  
High Production Rate ◽  
High Production ◽  
Incubation Temperatures ◽  
By Products

Abstract Background This work aims to study the optimal conditions of the fermentation culture medium used for the production of extracellular enzymes (amylase, cellulase, lipase, and protease) from previously isolated Aspergillus niger strains in date by-products. Results The five most powerful isolates selected based on the zone of degradation formed on Petri plates by the substrate were subjected to the quantitative evaluation of their enzymatic production. All five strains showed almost similar API-ZYM profiles, with minor variations observed at the level of some specific enzyme expression. The production of cellulase and amylase was depending on pH and incubation temperatures. ASP2 strain demonstrated the high production rate of amylase (at pH 5 and 30 °C) and cellulase (at pH 6 and 30 °C) for 96 h of incubation. Conclusion The A. niger showed the ability to produce several extracellular enzymes and can be used in the valorization of different agroindustrial residues.

scholarly journals Thermodynamic Behavior of Fe-Mn and Fe-Mn-Ag Powder Mixtures during Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 234
Author(s):  
Jakob Kraner ◽  
Jožef Medved ◽  
Matjaž Godec ◽  
Irena Paulin
Keyword(s):  
Selective Laser Melting ◽  
Manganese Oxides ◽  
Elevated Temperatures ◽  
Manganese Content ◽  
Chemical Compositions ◽  
Metal Powders ◽  
Laser Melting ◽  
Powder Mixtures ◽  
Ε Martensite ◽  
The Impact

Additive manufacturing is a form of powder metallurgy, which means the properties of the initial metal powders (chemical composition, powder morphology and size) impact the final properties of the resulting parts. A complete characterization, including thermodynamic effects and the behavior of the metal powders at elevated temperatures, is crucial when planning the manufacturing process. The analysis of the Fe-Mn and Fe-Mn-Ag powder mixtures, made from pure elemental powders, shows a high susceptibility to sintering in the temperature interval from 700 to 1000 °C. Here, numerous changes to the manganese oxides and the αMn to βMn transformation occurred. The problems of mechanically mixed powders, when using selective laser melting, were highlighted by the low flowability, which led to a less controllable process, an uncontrolled arrangement of the powder and a large percentage of burnt manganese. All this was determined from the altered chemical compositions of the produced parts. The impact of the increased manganese content on the decreased probability of the transformation from γ-austenite to ε-martensite was confirmed. The ε-martensite in the microstructure increased the hardness of the material, but at the same time, its magnetic properties reduce the usefulness for medical applications. However, the produced parts had comparable elongations to human bone.

Identification of Aspergillus flavus Isolates as Potential Biocontrol Agents of Aflatoxin Contamination in Crops

2013 ◽  
Vol 76 (6) ◽  
pp. 1051-1055 ◽  
Author(s):  
L. J. ROSADA ◽  
J. R. SANT'ANNA ◽  
C. C. S. FRANCO ◽  
G. N. M. ESQUISSATO ◽  
P. A. S. R. SANTOS ◽  
...  
Keyword(s):  
Biological Control ◽  
Aspergillus Flavus ◽  
Filamentous Fungus ◽  
Microscopic Examination ◽  
Genetic Recombination ◽  
Aflatoxin Contamination ◽  
Biocontrol Agents ◽  
Biological Control Agents ◽  
Nit Mutants ◽  
The Stability

Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops.

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