Manganese and iron oxidation by fungi isolated from building stone

Abstract

Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was necessary. Mn(II) oxidation in acidogenic strains was greater in a medium containing the highest concentrations of glucose, nitrate, and manganese. High concentrations of Fe(II), glucose, and mineral salts were optimal for iron oxidation. Mn(IV) precipitated as oxides or hydroxides adhered to the mycelium. Most of the Fe(III) remained in solution by chelation with organic acids excreted by acidogenic strains. Other metabolites acted as Fe(III) chelators in nonacidogenic strains, although Fe(III) deposits around the mycelium were also detected. Both iron and manganese oxidation were shown to involve extracellular, hydrosoluble enzymes, with maximum specific activities during exponential growth. Strains able to oxidize manganese were also able to oxidize iron. It is concluded that iron and manganese oxidation reported in this work were biologically induced by filamentous fungi mainly by direct (enzymatic) mechanisms.

Fungal biodeterioration in historic buildings of Havana (Cuba)

“…These acids form calcium salts or act as chelating agents of mineral kations, favouring the biodeterioration process. Ljaljevic and Vukojevic (2009) Torre & Gómez, 1994) have highlighted the acidogenic capacity of Alternaria tenuisima (isolated from wood), Cladosporium (from paper, textiles and wood), Mucor and Trichoderma (from textiles) and Fusarium (from protein-containing materials).…”

Mycotransformation of organic and inorganic substrates

“…pyromorphite (Pb 5 (PO 4 ) 3 Cl), contaminated soil and other solid wastes (Sayer et al, 1999). Fungi can also mobilize metals and attack mineral surfaces by redox processes (Grote & Krumbein, 1992;Gadd, 1993a;De la Torre & Gomez-Alarcon, 1994): Fe(III) and Mn(IV) solubility is increased by reduction to Fe(II) and Mn(II) respectively. Reduction of Hg(II) to volatile elemental Hg(0) can also be mediated by fungi (Gadd, 1993a,b).…”

“…The weathering of sandstone monuments by fungi has been attributed to the production of acetic, oxalic, citric, formic, fumaric, glyoxylic, gluconic, succinic and tartaric acids Hirsch et al 1995). Fungi can also attack rock surfaces through redox attack of mineral constituents (Grote & Krumbein, 1992;De la Torre & Gomez-Alarcon, 1994).…”

Promotion of Mn(II) Oxidation and Remediation of Coal Mine Drainage in Passive Treatment Systems by Diverse Fungal and Bacterial Communities

“…At the time of sampling, waters flowing into SRC1 had a near-neutral pH (6.6) Culture enrichments were initiated using Mn oxide-coated limestone and debris from the treatment systems. Serial dilutions to 1/10 4 for each sample were plated on 7 types of agarsolidified media with 20 mM HEPES (pH 7) and 200 M MnCl 2 : AY (34); K, M, and Leptothrix (46); J and J plus acetate (22); and medium 3 (11). Mn(II)-oxidizing microorganisms were transferred to fresh media until cultures were deemed axenic.…”