HR: 1340h
AN: B13C-1385    [Abstracts]
TI: Phosphorous availability influences the dissolution of apatite by soil fungi
AU: * Rosling, A
EM: Anna.Rosling@mykopat.slu.se
AF: 1, Department of Earth and Planetary Science, UC Berkeley, Mc Cone Hall, Berkeley, CA 94720-4767, United States
AU: Suttle, K B
AF: 1, Department of Earth and Planetary Science, UC Berkeley, Mc Cone Hall, Berkeley, CA 94720-4767, United States
AU: Johansson, E
AF: 2, Man-Technology-Environment Research Centre, Department of Natural Sciences, Oebro University, Orebro, 70182, Sweden
AU: van Hees, P W
AF: 2, Man-Technology-Environment Research Centre, Department of Natural Sciences, Oebro University, Orebro, 70182, Sweden
AU: Banfield, J F
AF: 1, Department of Earth and Planetary Science, UC Berkeley, Mc Cone Hall, Berkeley, CA 94720-4767, United States
AB: We conducted mineral dissolution experiments using fungi isolated from a grassland soil in northern California to determine the response of fungi to different levels of phosphorus availability and to identify pathways of apatite dissolution by fungal exudates. Fluorapatite dissolution experiments were performed either with fungi present or under abiotic conditions using cell-free liquid media conditioned by fungal growth at different phosphorus and calcium availabilities. Among biogeochemically active soil fungal isolates apatite dissolution was either active in response to phosphorus limiting growth conditions or passive as a result of mycelial growth. Zygomycete isolates in the order of Mucorales acidify their growth media substrate in the presence of phosphorus, mainly through production of oxalic acid. Cell-free exudates induced fluorapatite dissolution at a rate of 10 -0.9 ± 0.14 and 10 -1.2 ± 0.22 mmol P/m2/s. The Ascomycete isolate, in the family Trichocomaceae, induced fluorapatite dissolution at a rate of 10 - 1.1 ± 0.05 mmol P/m2/s by lowering the pH of the media under phosphorus-limited conditions, without producing significant amounts of low molecular weight organic acids (LMWOAs). Oxalate strongly etches fluorapatite along channels parallel to [001], forming needle like features, while exudates from Trichocomaceae induced surface rounding. We conclude that while LMWOAs are well-studied weathering agents these does not appear to be produced by fungi in response to phosphorus limiting growth conditions.
DE: 0409 Bioavailability: chemical speciation and complexation
DE: 0410 Biodiversity
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting