Geomycology is the study of the roles of fungi in geological processes. The biogeochemical importance of fungi is significant in several areas, including nutrient and element
cycling, rock, mineral ...and metal transformations, bioweathering and mycogenic biomineral formation. Such processes can occur in aquatic and terrestrial habitats, but it is the
terrestrial environment where fungi probably have the greatest geochemical influence. Of special significance are the mutualistic relationships with phototrophic organisms: lichens
(algae, cyanobacteria) and mycorrhizas (plants). Central to many geomycological processes are transformations of metals and minerals, and fungi possess many properties that effect
changes in metal speciation, toxicity and mobility, as well as mineral formation or mineral dissolution or deterioration. Some fungal transformations have potential applications in
environmental biotechnology, e.g. metal and radionuclide leaching, recovery, detoxification and bioremediation, and in the production or deposition of biominerals or metallic
elements with catalytic or other properties. Metal and mineral transformations may also result in adverse effects when these processes result in spoilage and destruction of natural
and synthetic materials, rock and mineral-based building materials (e.g. concrete), biocorrosion of metals, alloys and related substances, and adverse effects on radionuclide
speciation, mobility and containment.
Summary
Oxalic acid‐producing fungi play an important role in biogeochemical transformations of rocks and minerals and possess biotechnological potential for extraction of valuable elements from ...primary or waste ores and other solid matrices. This research investigates the extraction of phosphate from rock phosphate (RP) by oxalic acid. Reaction parameters were derived using pure oxalic acid solutions to solubilize RP. It was found that the oxalic acid concentration was the main factor driving reaction kinetics. Excess oxalic acid could retard the reaction due to calcium oxalate encrustation on RP surfaces. However, complete P extraction was reached at stoichiometric proportions of apatite and oxalic acid. This reaction reached completion after 168 h, although most of the P (up to 75%) was released in less than 1 h. Most of the Ca released from the apatite formed sparingly soluble calcium oxalate minerals, with a predominance of whewellite over weddellite. Bioleaching of RP employing biomass‐free spent culture filtrates containing oxalic acid (100 mM) produced by Aspergillus niger extracted ~ 74% of the P contained in the RP. These findings contribute to a better understanding of the reaction between apatite and oxalic acid and provide insights for potential applications of this process for biotechnological production of phosphate fertilizer.
This research investigates the extraction of phosphate from rock phosphate by abiotic and fungal‐produced oxalic acid. Complete P extraction was achieved at stoichiometric proportions of apatite and oxalic acid, with up to 75% P released in less than 1 h. Most of the Ca released from the apatite formed sparingly‐soluble calcium oxalate minerals.
The fern Pteris vittata can tolerate and hyperaccumulate levels of arsenic that would be toxic to other plants and animals. A recent study has shown that a bacterial-like tolerance mechanism has ...evolved in the fern, enabling it to tolerate and accumulate high concentrations of arsenic.
The fern Pteris vittata can tolerate and hyperaccumulate levels of arsenic that would be toxic to other plants and animals. A recent study has shown that a bacterial-like tolerance mechanism has evolved in the fern, enabling it to tolerate and accumulate high concentrations of arsenic.
In this research, the ureolytic fungi
Neurospora crassa
,
Pestalotiopsis
sp. and
Myrothecium gramineum
were investigated for the preparation of nanoscale copper carbonate and the role of fungal ...extracellular protein in such mineral formation. After incubation in urea-modified media, carbonate-laden fungal supernatants were used for the precipitation of copper carbonate, with experimental results agreeing closely with those obtained using geochemical modelling (Geochemist’s Workbench). Compared with commercial and chemically synthesized copper carbonate, the minerals obtained using fungal supernatants were nanoscale and showed varying morphologies. It was found that extracellular protein played an important role in determining the size and morphology of the carbonate minerals precipitated, and after mixture with CuCl
2
and resultant copper carbonate precipitation, more than 80% protein was removed from the
N. crassa
supernatant. Moreover, with addition of extracellular protein extracted from different fungal supernatants or standard bovine serum albumin, more than 96% of protein was removed by carbonate mineral precipitation. These results provide direct experimental evidence for the preparation of copper carbonate nanoparticles utilizing fungal ureolytic activity and show that fungal extracellular protein plays an important role in the formation and size of specific nano metal carbonates. Such a process provides opportunities for production of specific and/or novel metal carbonate nanoparticles of applied relevance, and as precursors of other useful biomineral products such as oxides.
Bioleaching is a proven bioprocess for metal recovery by solution from solid matrices, while a bioprecipitation or biomineralization approach is of potential for biorecovery from solution. Fungi can ...directly and indirectly mediate the formation of many kinds of minerals, including oxides, phosphates, carbonates and oxalates, as well as elemental forms of metals and metalloids such as Ag, Se and Te. Fungal capabilities may offer a potentially useful contribution to biotechnological and physico‐chemical methods for metal recovery.
A range of fungal species showed variable abilities to colonize and penetrate a mortar substrate. Calcium biomineralization was a common feature with calcium-containing crystals deposited in the ...microenvironment or encrusting hyphae, regardless of the specific mortar composition. Several species caused significant damage to the mortar surface, exhibiting burrowing and penetration, surface etching, and biomineralization. In some cases, extensive biomineralization of hyphae, probably by carbonatization, resulted in the formation of crystalline tubes after hyphal degradation on mortar blocks, including those amended with Co or Sr carbonate. Ca was the only metal detected in the biomineralized formations with Co or Sr undetectable. Aspergillus niger, Stemphylium sp. and Paecilomyces sp. could penetrate mortar with differential responses depending on the porosity. Fluorescent staining of thin sections recorded penetration depths of ∼530 um for A. niger and ∼620 um for Stemphylium sp. Penetration depth varied inversely with porosity and greater penetration depths were achieved in mortar with a lower porosity (lower water/cement ratio). These results have provided further understanding of biodeteriorative fungal interactions with cementitious substrates that can clearly affect structural integrity. The potential significance of fungal colonization and such biodeteriorative phenomena should not be overlooked in built environment contexts, including radionuclide storage and surface decontamination.
Biomineralization of CaCO3 by microorganisms is a well-documented process considered applicable to concrete self-healing and metal bioremediation. Urea hydrolysis is the most widely explored and ...efficient pathway regarding concrete bioprotection. However, the potential of fungi has received relatively little attention compared to bacteria. In this work, we show that Fusarium cerealis, Phoma herbarum and Mucor hiemalis, isolated from concrete, could produce 828.6–941.3 mg L−1 ammonium‑nitrogen in liquid media through urea hydrolysis indicating significant urease activity, and could grow in moderate (pH 8.3) or even extremely alkaline (pH 10.6) conditions. After culture in media containing 50 mM CaCl2, at least 48.8% Ca2+ was removed from solution by the selected fungi as calcite. The accumulation of Ca by the biomass was around 83.64–114.21 mg g−1. In addition, all fungi could mediate strontium carbonate formation with F. cerealis processing the highest ability for Sr removal, with ~61% added Sr being removed from solution. Scanning electron microscopy showed carbonate biominerals were encrusted on hyphae or aggregated in fungal pellets. When equivalent concentrations of Ca2+ and Sr2+ were supplemented to the media, CaCO3 with incorporated Sr formed with F. cerealis and M. hiemalis, and Sr(Sr, Ca)(CO3)2 with P. herbarum. Our results demonstrate the potential of fungi in providing carbonate coatings for concrete surfaces and simultaneous immobilization of Sr. We anticipate our work will promote further practical field research on porous cementitious materials protection by fungi and immobilization of potentially toxic metals from metal-laden ingredients, such as fly ash and granulated ground blast furnace slag.
Display omitted
•Fungi isolated from concrete were able to adapt to an alkaline environment.•Urease-positive fungi mediated calcium and strontium carbonate formation through urea hydrolysis.•Strontium could be sequestered into calcium carbonate or co-precipitated with calcium to form Sr(Sr, Ca)(CO3)2.•Fungal carbonate formation has potential for bioprotection of porous structural materials and toxic metal bioremediation.
SUMMARYFungi are ubiquitous and important biosphere inhabitants, and their abilities to decompose, degrade, and otherwise transform a massive range of organic and inorganic substances, including ...plant organic matter, rocks, and minerals, underpin their major significance as biodeteriogens in the built environment and of cultural heritage. Fungi are often the most obvious agents of cultural heritage biodeterioration with effects ranging from discoloration, staining, and biofouling to destruction of building components, historical artifacts, and artwork. Sporulation, morphological adaptations, and the explorative penetrative lifestyle of filamentous fungi enable efficient dispersal and colonization of solid substrates, while many species are able to withstand environmental stress factors such as desiccation, ultra-violet radiation, salinity, and potentially toxic organic and inorganic substances. Many can grow under nutrient-limited conditions, and many produce resistant cell forms that can survive through long periods of adverse conditions. The fungal lifestyle and chemoorganotrophic metabolism therefore enable adaptation and success in the frequently encountered extremophilic conditions that are associated with indoor and outdoor cultural heritage. Apart from free-living fungi, lichens are a fungal growth form and ubiquitous pioneer colonizers and biodeteriogens of outdoor materials, especially stone- and mineral-based building components. This article surveys the roles and significance of fungi in the biodeterioration of cultural heritage, with reference to the mechanisms involved and in relation to the range of substances encountered, as well as the methods by which fungal biodeterioration can be assessed and combated, and how certain fungal processes may be utilized in bioprotection.
Bacterial infection and corrosion are two of the most common causes of the failure for the use of biomedical metallic implants. In this paper, we developed a facile two-step approach for synthesizing ...a TiO2-PTFE nanocomposite coating on stainless steel substrate with both antibacterial and anticorrosion properties by using a sol-gel dip coating technique. A sub-layer of bioinspired polydopamine (PDA) was first coated on the stainless steel substrate to improve the adhesion and reactivity, then TiO2-PTFE was uniformly co-deposited onto the PDA sub-layer. Both PTFE and TiO2 contents had a significant influence on the surface energy of the TiO2-PTFE coating. The coating with the total surface energy of 26 mJ/m2 exhibited minimal bacterial adhesion against both Gram-negative Escherichia coli WT F1693 and Gram-positive Staphylococcus aureus F1557, which was explained using the extended DLVO theory. Benefiting from the synergistic effect between TiO2 and PTFE, the TiO2-PTFE coating showed improved corrosion resistance in artificial body fluids compared with the sole TiO2 coating or PTFE coating. The TiO2-PTFE coating also demonstrated extraordinary biocompatibility with fibroblast cells in culture, making it a prospective strategy to overcome current challenges in the use of metallic implants.
•TiO2-PTFE coatings were prepared via a sol-gel process using PDA as an intermediate layer•The PDA layer improved adhesion strength and uniformity of the coating•The TiO2-PTFE coating demonstrated significant antibacterial activity, corrosion resistance and biocompatibility
PDF
