Ferrous iron oxidation and rusticyanin in halotolerant, acidophilic 'Thiobacillus prosperus'

Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK Correspondence Paul R. Norris P.R.Norris{at}warwick.ac.uk The halotolerant acidophile ‘ Thiobacillus prosperus ’ was shown to require chloride for growth. With ferrous iron as substrate, growth occurred at a rate similar to that of the well-studied acidophile Acidithiobacillus ferrooxidans . Previously, the salt (NaCl) requirement of ‘ T. prosperus ’ was not clear and its growth on ferrous iron was described as poor. A subtractive hybridization of cDNAs from ferrous-iron-grown and sulfur-grown ‘ T. prosperus ’ strain V6 led to identification of a cluster of genes similar to the rus operon reported to encode ferrous iron oxidation in A. ferrooxidans . However, the ‘ T. prosperus ’ gene cluster did not contain a homologue of cyc1 , which is thought to encode a key cytochrome c in the pathway of electron transport from ferrous iron in A. ferrooxidans . Rusticyanin, another key protein in ferrous iron oxidation by A. ferrooxidans , was present in ‘ T. prosperus ’ at similar concentrations in cells grown on either ferrous iron or sulfur. Abbreviations: DP, difference product; mRDA, micro-representational difference analysis; SD, Shine–Dalgarno Present address: Green Biologics Ltd, Unit 45A, Milton Park, Abingdon, Oxfordshire OX14 4RU, UK. Present address: National Blood Service, Southmead Road, Bristol BS10 5ND, UK. Present address: Institut für Ingenieurbiologie und Biotechnologie des Abwassers, Universität Karlsruhe (TH), Am Fasanengarten, 76128 Karlsruhe, Germany. The GenBank accession numbers for the partial 16S rRNA gene sequences of ‘ T. prosperus ’ strain V6 and ‘ T. prosperus ’ (DSM 5130) are EU653290 and EU653291, respectively. The GenBank accession number for the sequence of the genomic DNA region containing the strain V6 rus -operon-like gene cluster is EU653292.