Papers by Author: Paul R. Norris

Abstract: Novel iron- and sulfur-oxidizing, moderate thermophiles were isolated from an acidic geothermal site and from a previously studied, pyrite-enrichment mixed culture (which also contained the related actinobacterium Acidimicrobium ferrooxidans). The novel species (proposed genus “Acidithiomicrobium”) grew autotrophically with ferrous iron at an optimum temperature of about 50°C, efficiently degraded pyrite at 55°C and also grew well autotrophically on sulfur. The extensive dissolution of pyrite during autotrophic growth contrasted with a requirement for yeast extract for significant growth of the related Acidimicrobium ferrooxidans.

Abstract: Thermotolerant “Thiobacillus prosperus”-like bacteria were enriched from warm, acidic sediments of the island of Milos in the Aegean Sea. Analysis of 16S rRNA gene sequences indicated at least two thermotolerant species, with at least one of them present in similar niches at Vulcano, Italy. Iron solubilization in a pyrite-enrichment culture at 47°C was most rapid in the presence of NaCl at 30 g.l 1. One of the novel species (strain M7) grew in pure culture on pyrite with NaCl at 50 g.l-1, but iron solubilization was most rapid with 20 g NaCl.l 1 at just below 50°C.

Abstract: Growth on ferrous iron of a new isolate of the halotolerant acidophile “Thiobacillus prosperus” occurred with a substrate oxidation rate similar to that of Acidithiobacillus ferrooxidans, but with a requirement for salt (NaCl). These observations contrast with the previous description of “T. prosperus” in which a salt requirement was not noted and growth on ferrous iron was described as poor. As well as similar capacities for iron oxidation, these species were shown to possess similar clusters of genes (the rus operon) that encode proteins likely to be involved in transfer of electrons from ferrous iron. There were some differences in the organization of the genes and one of them that encodes a cytochrome c in At. ferrooxidans was absent from the “T. prosperus” cluster.

Abstract: The Bioshale project, involving 13 partners throughout Europe, is co-funded by the European Commission under the FP6 program. The main objective of this project (which started in October 2004) is to identify and develop innovative biotechnological processes for ‘’eco-efficient’’ exploitation of metal-rich, black shale ores. Three extensive deposits have been selected for R&D actions. These are: (i) a site (in Talvivaara, Finland) that, at the outset of the project, had not been exploited; (ii) a deposit (in Lubin, Poland) that is currently being actively mined, and (iii) a third site (in Mansfeld, Germany) where the ore had been actively mined in the past, but which is no longer exploited. The black shale ores contain base (e.g. copper and nickel), precious (principally silver) and PGM metals, but also high contents of organic matter that potentially handicap metal recovery by conventional techniques. The main technical aspects of the work plan can be summarized as: (i) evaluation of the geological resources and selection of metal-bearing components; (ii) selection of biological consortia to be tested; (iii) assessment of bioprocessing routes, including hydrometallurgical processing; (iv) techno-economic evaluation of new processes from mining to metal recovery including social, and (v) assessing the environmental impacts of biotechnological compared to conventional processing of the ores. An overview of the main results obtained to date are presented, with special emphasis on the development of bioleaching technologies for metal recovery that can be applied to multielement concentrates and black shale ores.