Oxalate formation byAspergillus nigeron minerals of manganese ores

Abstract

Microscopic fungi (micromycetes) play an important role in rock alteration often leading to formation of insoluble biogenic oxalates on rock/mineral surfaces. Oxalate crystallization under the influence of fungus Aspergillus niger (one of the most active stone destructors) was studied in vitro on two Mn,Ca-bearing minerals of manganese ores: todorokite (Na0.36,Ca0.09,K0.06,Sr0.03,Ba0.02)0.56(Mn5.53,Mg0.47)O12•3-4H2O and kutnohorite (Ca0.77,Mn0.23)(Mn0.74,Fe0.14,Mg0.11)(CO3)2. The underlying minerals and the products of their alteration were investigated using powder and single crystal X-ray diffraction, optical microscopy, SEM and EDX methods. It was shown that a more intense leaching of Ca-ions (compared to Mn-ions) from todorokite and kutnohorite leads to an earlier crystallization of calcium oxalates (predominantly whewellite) compared to manganese oxalates (lindbergite, falottaite). Crystallization of manganese oxalates on the surface of kutnohorite occurs in more acidic (compared to todorokite) medium through the formation of mycogenic Mn,Ca-bearing oxides, which are close in composition and structure to This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

Biogenic Orthorhombic α-Calcium Formate from Sediments of Alkali Lake, Oregon, USA

“…An interaction of biogenic and abiogenic systems in nature and in laboratory conditions quite often leads to the formation of new materials, in particular mineral or minerallike species. Oxalate minerals, which are formed when the metabolic products of bacteria, micromycetes and lichens interact with rocks and minerals [21][22][23][24], can be regarded as a striking example of such interactions. Oxalic acid is not the only known product of the living cycle; organic acids such as acetic, citric, formic, and etc.…”

Mycosynthesis of Zinc Oxide Nanoparticles Exhibits Fungal Species Dependent Morphological Preference

“…The goal of our study was to enhance our understanding of parameters that underlie the ability of fungi to synthesize ZnO NPs, specifically focusing on the role of fungal species and metal precursors. Here, we present the mycosynthesis of ZnO NPs from cell-free exudates of five fungi shown to produce organic acid-rich exudates: Aspergillus niger van Tieghem, [27][28][29] Aspergillus versicolor (Vuillemin) Tiraboschi, [29,30] Cladosporium cladosporioides (Fresen.) G.A.…”

Iron Oxalate Humboldtine Crystallization by Fungus Aspergillus niger

“…On the 18th day, they fully covered the pyrrhotite surface (Figure 3e). Spherulite-like intergrowths of humboldtine crystals on siderite (Figure 2c) were typical for Mn oxalate dihydrate lindbergite, synthesized by us under the action of A. niger [33], and are isostructural to humboldtine.…”

“…The earlier formation of humboldtine on pyrrhotite as compared to siderit indicates that the solubilization and crystallization processes leading to the iron oxalat formation on these substrates differ significantly. At the hypothesis level, by analogy with modeling Mn oxalates under the action of A. niger previously performed by us [33], thi can be explained via complex redox processes (Fe 2+ to Fe 3+ and vice versa), which depend on the oxidation state of iron ions in the underlying mineral substrate and on the pH o the crystallization medium. The slower crystallization of humboldtine on pyrrhotite a compared to siderite indicates a lower solubility of pyrrhotite and iron oxides and hy droxides replacing it in the products of fungus metabolism.…”