Zinc phosphate and pyromorphite solubilization by soil plant-symbiotic fungi

M. Fomina, Ian James Alexander, S. Hillier, G. M. Gadd

Research output: Contribution to journalArticlepeer-review

110 Citations (Scopus)

Abstract

Acidolysis, complexolysis and metal accumulation were involved in solubilization of zinc phosphate and pyromorphite by a selection of soil fungi representing ericoid and ectomycorrhizal plant symbionts and an endophytic/entomopathogenic fungus, Beauveria caledonica. Zinc phosphate was much more readily solubilized than pyromorphite. According to the relationship between metal mobilization and pH, acidolysis (protonation) was found to be the major mechanism of both zinc phosphate and pyromorphite dissolution for most of the fungi examined. In general, the more metal tolerant fungal strains yielded more biomass, acidified the medium more and dissolved more of the metal mineral than less tolerant strains. However, B. caledonica 4 excreted a substantial amount of oxalic acid (similar to0.8 mM) in the presence of pyromorphite that coincided with a dramatic increase in lead mobilization providing a clear example of complexolysis. Organic acid excretion by fungi was inter- and intraspecific and was strongly influenced by the presence of the toxic metal minerals. When grown on zinc phosphate or pyromorphite, Hymenoscyphus ericae DGC3(UZ) accumulated the lowest metal concentration, but Thelephora terrestris accumulated the highest metal concentration in the biomass. The ability to accumulate water-soluble lead species, representing mainly cytosolic and vacuolar pools, seemed to be connected with pyromorphite-solubilizing ability. B. caledonica 4, which demonstrated the highest ability to dissolve pyromorphite, accumulated the highest water-soluble fraction and total lead concentration in the mycelium. Generally, isolates with a higher zinc-tolerance accumulated significantly less total zinc from zinc phosphate (including the sum of water-soluble and NaCl-extractable zinc) than non-tolerant strains.

Original languageEnglish
Pages (from-to)351-366
Number of pages15
JournalGeomicrobiology Journal
Volume21
DOIs
Publication statusPublished - 2004

Keywords

  • entomopathogenic fungi
  • metal accumulation
  • mycorrhizal fungi
  • organic acids
  • oxalic acid
  • pyromorphite
  • solubilization
  • zinc phosphate
  • ECTOMYCORRHIZAL PINUS-SYLVESTRIS
  • NATURAL GYPSUM CASO4.2H(2)O
  • ERICOID MYCORRHIZAL FUNGI
  • HEAVY-METAL TOLERANCE
  • ORGANIC-ACIDS
  • OXALIC-ACID
  • ASPERGILLUS-NIGER
  • CALCIUM-OXALATE
  • CITRIC-ACID
  • SCLEROTINIA-SCLEROTIORUM

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