Showing papers by "Franz Schinner published in 1989"

Extraction of Zinc from Industrial Waste by a Penicillium sp.

Abstract: Zinc was extracted from a filter residue of a copper works (58.6% zinc) by a Penicillium sp. isolated from a metal-containing location. By isotachophoresis citric acid was identified as the leaching agent. Citrate was only formed when the leaching substrate was present. This production of citrate was different in several ways from that achieved by Aspergillus niger: glucose was utilized before fructose; the initial concentration of zinc was 50 to 500 times higher than usual in citrate fermentations with A. niger; citrate production stopped when 80 to 90% of the zinc was leached, although sufficient sugar for further synthesis was still present; and in synthetic media citrate production by A. niger needs an acidic environment (pH 2), while the formation of citric acid by Penicillium sp. occurred in a pH range of 7 to 4. Tests with different concentrations of waste material (0.5, 2.5, and 5%) showed that the highest yield of solubilized zinc occurred with a 2.5% substrate (93% zinc extracted after 13 days).

Selective accumulation of silver by fungi

Abstract: APhoma sp., tolerating 1 mmol/l Ag+, and 32 other fungi from a culture collection (not selected for their metal tolerance), were tested for their ability to accumulate silver, cadmium, copper, nickel and lead ions from aqueous solutions. Silver was accumulated selectively. Bivalent ions Cu, Cd, Ni and Pb were partially released after about 50 min, whereas the monovalent Ag ion remained bound. The selectivity of thePhoma sp. for silver developed in the late linear growth phase and might be connected with the occurence of a slimy exopolymer. The mean accumulation of the five heavy element ions by 32 strains of fungi could not be correlated with the ionic radii of the ions.