Biosorption and bioaccumulation of lead by Penicillium sp. Psf-2 isolated from the deep sea sediment of the Pacific Ocean.

A lead resistant fungus was isolated from the Pacific sediment. It was associated with Penicillium according to its partial sequences of 18S and ITS. The fungus could grow in the presence of 24 mM Pb(NO(3))(2 )in a liquid medium, and no growth inhibition was observed at 4 mM and below. When growing in the presence of 4 mM Pb(NO(3))(2), the fungus accumulated a large amount of lead granules in the cell, as well as adsorbed on the outer layer of cell wall, as observed under a transmission electron microscope. The intracellular lead deposited either in the vicinity of the cytoplasm membrane or in the vacuoles, and also could aggregate into large particles in the cytoplasm. However, lead was not adsorbed on the thick inner wall of the fungus. Energy dispersive X-ray spectroscopy analysis showed that these granules or particles mainly consisted of lead, and other elements could hardly be detected. Selected area electron diffraction analysis showed that there were regular crystalline lattices in the lead precipitates, indicating that they were actually in the form of crystals to some extent. Therefore, both intracellular bioaccumulation and extracellular biosorption had contributed to the high resistance of this fungus to lead. These results suggest that this fungus can be used in biotreatment as a lead trapper.