Screening of Penicillium Strain with High Copper Resistance and Its Adsorption of Heavy Metals

A strain of Penicillium with high resistance to heavy metals, especially to copper, was isolated from copper mining soil. The tolerance concentrations of the strain to Cu2+, Zn2+, Pb2+, Ni2+, Cr6+ and Cd2+ were 150, 150, 35, 15, 5 and 5 mmol/L, respectively. Under the stress of 40 mmol/L Cu2+, the optimal temperature and pH for the strain growth were 30 and 7.0. Its best carbon and nitrogen sources were farina, peptone or (NH4)2SO4, and its growth speed could be effectively accelerated by adding oxalic acid or citric acid. The analyses based on atomic absorption indicated that 98 % of Cu2+ was adsorbed from copper solutions at pH 5.0 and with 10 mg/L of Cu2+ in 45 minutes. In a solution with pH 6.0 and 100 mg/L of each heavy metal ion, the adsorptions of Cu2+, Zn2+, Pb2+, Cr6+, Ni2+ and Cd2+ were 22.8, 8.9, 18.2, 4.3, 8.4, and 5.5 mg/g, respectively. The existence of Cu2+ in the solution could inhibit the adsorptions of Zn2+, Pb2+, Ni2+ and Cd2+ by the strain. The adsorption of Cr6+ was promoted slightly when it was compounded with Cu2+, but there was still no signif icance between these two adsorption quantities. Fig 3, Tab 2, Ref 22