Cadmium tolerance and bioremediation potential of filamentous fungus Penicillium chrysogenum FMS2 isolated from soil

Cadmium-tolerant fungus, designated as strain FMS2, was isolated from metal-polluted soil collected from Lahore, Pakistan, and its role in cadmium bioremediation was investigated. Strain FMS2 was identified as Penicillium chrysogenum through sequence analysis of the internal transcribed spacer (ITS) regions. Physicochemical growth factors and maximum tolerance level to cadmium were determined. Cadmium uptake and bioremoval potential were analyzed by atomic absorption spectrophotometry, scanning electron microscopy and energy-dispersive spectroscopic analysis, whereas its distribution inside the fungal cell was detected by scanning transmission electron microscopy and electron energy loss spectroscopy. P. chrysogenum FMS2 was found to be resistant to cadmium with a maximum tolerance level up to 1000 mg l −1 . Strain FMS2 can grow under a wide range of temperature (15–35 °C) and pH conditions (4.0–12.0). The cadmium removal capacity of strain FMS2 was observed as 49 ± 0.8% within 15 days after exposure. Distinct white patches were observed in scanning electron micrographs with clear peaks of cadmium in energy-dispersive spectroscopic spectra indicating cadmium biosorption. The scanning transmission electron micrographs and electron energy loss spectra of strain FMS2 cells revealed cytoplasmic localization of cadmium.