Extracellular biosynthesis of magnetite using fungi

Atul Bharde, Debabrata Rautaray, Vipul Bansal, Absar Ahmad, Indranil Sarkar, Seikh Mohammad Yusuf, Milan Sanyal, Murali Sastry

Research output: Contribution to journalArticleResearchpeer-review

348 Citations (Scopus)


The development of synthetic processes for oxide nanomaterials is an issue of considerable topical interest. While a number of chemical methods are available and are extensively used, the collaborations are often energy intensive and employ toxic chemicals. On the other hand, the synthesis of inorganic materials by biological systems is characterized by processes that occur at close to ambient temperatures and pressures, and at neutral pH (examples include magnetotactic bacteria, diatoms, and S-layer bacteria). Here we show that nanoparticulate magnetite may be produced at room temperature extracellularly by challenging the fungi, Fusarium oxysporum and Verticillium sp., with mixtures of ferric and ferrous salts. Extracellular hydrolysis of the anionic iron complexes by cationic proteins secreted by the fungi results in the room-temperature synthesis of crystalline magnetite particles that exhibit a signature of a ferrimagnetic transition with a negligible amount of spontaneous magnetization at low temperature.

Original languageEnglish
Pages (from-to)135-141
Number of pages7
Issue number1
Publication statusPublished - Jan 2006
Externally publishedYes


  • Biosynthesis
  • Extracellular growth
  • Fungi
  • Magnetite
  • Nanopartictes

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