Fungal biomineralization of lead phosphates on the surface of lead metal

- Biomineralization of lead phosphates by fungi on lead metal surface.
- Microscopic analyses reveal the formation of biogenic secondary minerals.
- Lead biomineralization as biological process to cope with the toxicity of Pb.

The present work describes lead phosphate biomineralization by a wood-decaying fungal isolate, Penicillium chrysogenum A15, after incubation in solid medium with metallic lead (Pb shot pellets). This fungal isolate showed high tolerance to this element, being able to grow on solid medium containing 8 mM Pb(II). Environmental Scanning Electron Microscope (ESEM) observations of abiotic controls showed the presence of lead oxide crystals on the lead shot surface after 8 weeks incubation. However, in presence of P. chrysogenum, lead phosphate mineral phases were detected as aggregates on the surface of lead shots after 2-weeks and 8-weeks incubation. The morphology of the biotically deposited secondary minerals showed significant differences in comparison to those produced under abiotic conditions, appearing globular, prismatic and acicular crystals. High Resolution Transmission Electron Microscope (HRTEM) analysis indicated deposition of lead phosphates on the cell surface which could be considered as Pb resistance mechanism used by this isolate to cope with toxicity of lead. This study extends the spectrum of fungal isolates with potential on the biomineralization of lead phosphates useful for the bioremediation of lead contaminated sites.