title: Routes of phlogopite weathering by three fungal strains.
abstract: Fungi dissolve soil minerals by acidification and mechanical disruption. Dissolution may occur at the microscale (contact between fungus and mineral) and medium scale (entire mineral grains). Mineral weathering by fungi and other microorganisms is thought to be of significant global contribution, perhaps producing specific weathering signatures. We report fungal dissolution of phlogopite mica in experiments with three fungal strains (Alternaria tenuissima, Cladosporium cladosporioides, Stilbella sp.) on solid medium for 30 days at 21 °C and 96-100% relative humidity. The study used variable-pressure SEM-EDS equipped with charge contrast imaging. Statistical analysis of the results discriminated between the weathering activities of the three fungal species, which increased from Stilbella sp. to C. cladosporioides to A. tenuissima, in agreement with the respective decreasing pH in the media (6.4, 5.8, 5.2 ± 0.03). Phlogopite weathering features were irregular and variable, apparently not caused by direct contact with fungal hyphae. EDS values indicated two or more dissolution mechanisms, one of them suggesting cation rearrangement in the mica towards formation of Al-rich smectite. Intimate fungus-mineral interaction was observed, and the lack of observable dissolution traces from such contact interaction is interpreted as the result of effacing by the more intense acid leaching operating at larger scale.
authors.affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro Agricoltura Ambiente, Via della Navicella 2-4, 00184 Rome, Italy; Department of Life Sciences, Natural History Museum, Cromwell Road, SW7 5BD London, UK. Electronic address: flavia.pinzari@crea.gov.it.
authors.forename: Flavia
authors.initials: F
authors.lastname: Pinzari
authors.affiliation: Department of Earth Sciences, Natural History Museum, Cromwell Road, SW7 5BD London, UK.
authors.forename: Javier
authors.initials: J
authors.lastname: Cuadros
authors.affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro Agricoltura Ambiente, Via della Navicella 2-4, 00184 Rome, Italy.
authors.forename: Rosario
authors.initials: R
authors.lastname: Napoli
authors.affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro Agricoltura Ambiente, Via della Navicella 2-4, 00184 Rome, Italy.
authors.forename: Loredana
authors.initials: L
authors.lastname: Canfora
authors.affiliation: Department of Earth Sciences, Natural History Museum, Cromwell Road, SW7 5BD London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Baussà Bardají
mesh_terms: D000528:Alternaria / Q000378:metabolism*; D000538:Aluminum Silicates / Q000378:metabolism*; D002963:Cladosporium / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D004783:Environmental Microbiology; D006863:Hydrogen-Ion Concentration; D006999:Hypocreales / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D013696:Temperature
chemical_list: D000538:Aluminum Silicates; D003470:Culture Media; C011934:mica
keywords: Bioweathering; Fungi; Geomicrobiology; Mica; SEM-EDS