Bioaccumulation and biosorption activities of indoor metal-tolerant penicillium simplicissimum for removal of toxic metals

In this study, the bioaccumulation and biosorption of aqueous metals (cadmium, copper, lead, zinc and trivalent chromium) by live and dead cells of Penicillium simplicissimum (isolate 10) were investigated and compared. Removal experiments under varying cell concentrations, pH and initial metal concentrations revealed that live cells generally achieved highest metal removal rates when 0.80 g fresh weight of cells was used, with metal solutions at pH 5 and concentrations of 50–100 mg L⁻¹ (up to 150 and 200 mg L⁻¹ for cadmium and lead, respectively). On the contrary, biosorption of metals by dead cells occurred at maximum rates when as little as 0.15 g dry weight of cells was used, in conditions of pH 5–7 (metal dependent) and lower metal concentration of 50 mg L⁻¹. This comparative analysis suggested that although effective bioremediation by live cells required more cell biomass and preferred the five metals at concentrations of 50–100 mg L⁻¹, the amount of metals removed by live cells were significantly higher (36.2–86.4% for 100 mg L⁻¹ and pH 5) than by dead cells (8.5–58.9%). The results indicated that bioaccumulation is a favourable process that aids in metal removal together with biosorption, and is presumably more effective than the independent process of biosorption alone (by dead cells). Hence, the metal removal potential of P. simplicissimum, especially live cells of this indoor metal-tolerant isolate, may be applied to wastewaters for effective removal within optimum pH range and metal concentrations. Graphic Abstract: [Figure not available: see fulltext.].