Characteristics of high resistance to heavy metal salts and uptake of Cu~(2+) and Zn~(2+) ions of Penicillium janthinellum

A strain of Penicillium numbered GXCR was isolated from polluted sludge of a mining area of Guangxi. It was identified as Penicillium janthinellum according to morphology and the DNA sequence homology of internal transcribed spacer region of the 5.8S rRNA. The GXCR tolerated 200 mmol L-1 of Cu2+, and grew on PDA plate containing up to 800 mmol L–1 of Cu2+ in the presence of 5 mmol L–1 of Mn2+. As for other metal salts, the minimum concentrations (mmol L–1) required to inhibit the GXCR growth on PDA plate were in order of Zn2+, 1200; Al3+, 500; Na+, 250; Mn2+, 200; Cd2+, 50; Cr3+, 60; Cr6+, 3; Ni2+, 20; Pb2+, 50. The resistance of the GXCR to Cu2+, Cr6+, Pb2+ and Zn2+ was dependent upon pH, and decreased sharply with increase of pH ranging from 3 to 7. The results from an orthogonal experiment [L9(43)] of growth of the GXCR in PDL supplemented with mix of three metal salts revealed the significant synergism among metal saltsin their toxicity to the GXCR , the synergism was correlated not only with type of metal-salts but also with ratio of concentrations among metal-salts. The strain had higher levels of resistance to mix of three metal salts. The analysis based on atomic absorption indicated that Cu2+uptake in deionized water supplemented with 20 mmol L–1 of Cu2+ were 38.1 mg g-1 natural dry mycelia (DM) and 76.9mg g-1 DM pre-treated with 200 mmol L–1 of NaOH, and Zn2+uptake in PDL(PDA without agar) containing 1200 mmol L–1 of Zn2+ by mycelia of a 7-day continuous culture that initiated with inoculation of conidia was 258.3 mg g-1 DM.