Formation of water-soluble metal cyanide complexes from solid minerals byPseudomonas plecoglossicida

Abstract

A few Pseudomonas species are able to form hydrocyanic acid (HCN), particularly when grown under glycine-rich conditions. In the presence of metals, cyanide can form water-soluble metal complexes of high chemical stability. We studied the possibility to mobilize metals as cyanide complexes from solid minerals using HCN-forming microorganisms. Pseudomonas plecoglossicida was cultivated in the presence of copper- and nickel-containing solid minerals. On powdered elemental nickel, fast HCN generation within the first 12 h of incubation was observed and water-soluble tetracyanaonickelate was formed. Cuprite, tenorite, chrysocolla, malachite, bornite, turquoise, millerite, pentlandite as well as shredded electronic scrap was also subjected to a biological treatment. Maximum concentrations of cyanide-complexed copper corresponded to a solubilization of 42% and 27% when P. plecoglossicida was grown in the presence of cuprite or tenorite, respectively. Crystal system, metal oxidation state and mineral hydrophobicity might have a significant influence on metal mobilization. However, it was not possible to allocate metal mobilization to a single mineral property. Cyanide-complexed gold was detected during growth on manually cut circuit boards. Maximum dicyanoaurate concentration corresponded to a 68.5% dissolution of the total gold added. These findings represent a novel type of microbial mobilization of nickel and copper from solid minerals based on the ability of certain microbes to form HCN.

Weathering-Associated Bacteria from the Damma Glacier Forefield: Physiological Capabilities and Impact on Granite Dissolution

“…The impact of HCN on mineral weathering was examined in just a few studies. Several HCNforming strains from the genus Pseudomonas were shown to dissolve minerals (15). However, our Pseudomonas isolate from the forefield of the Damma glacier did not form HCN under our experimental conditions.…”

“…The supplies of the organic acids were adjusted to the carbon concentrations of the growth medium. Cyanide produced by cyanogenic bacterial strains is known to solubilize metals from electronic waste material (15). Cyanide was added as KCN.…”

Biomobilization of silver, gold, and platinum from solid waste materials by HCN-forming microorganisms

“…Nevertheless, our results show that microbial mobilization of metals from solid materials as cyanide complex is possible. So far, only gold mobilization by C. violeceum has been addressed in earlier reports (Campbell et al, 2001;Kita at al, 2006;Lawson et al, 1999;Smith and Hunt, 1985), but cyanogenic microorganisms are also able to mobilize iron, copper, nickel, silver, gold, and platinum (Faramarzi et al, 2004;Faramarzi and Brandl, 2006). In contrast to other bioleaching techniques (Brandl, 2001), metal mobilization by cyanogens occurs under alkaline conditions.…”

Bio-Reclamation of Strategic and Energy Critical Metals from Secondary Resources

“…During the bioleaching, an increase in free cyanide concentration to 3.6 mg/L under the varied pH (6.7 to 9.0) and dissolved oxygen concentration (2 to 5 mg/L) clearly demonstrated the growth characteristics of Bacillus megaterium. A lower leachability of Pt can be attributed to its resistance to being mobilized using the cyanogenic microorganisms [26,105]. Recovery of Re from a waste water employing biosorption technique has also been studied.…”