title: Reconstruction of the Metabolic Potential of AcidophilicSideroxydansStrains from the Metagenome of an Microaerophilic Enrichment Culture of Acidophilic Iron-Oxidizing Bacteria from a Pilot Plant for the Treatment of Acid Mine Drainage Reveals Metabolic Versatility and Adaptation to Life at Low pH.
abstract: Bacterial community analyses of samples from a pilot plant for the treatment of acid mine drainage (AMD) from the lignite-mining district in Lusatia (East Germany) had previously demonstrated the dominance of two groups of acidophilic iron oxidizers: the novel candidate genus "Ferrovum" and a group comprisingGallionella-like strains. Since pure culture had proven difficult, previous studies have used genome analyses of co-cultures consisting of "Ferrovum" and a strain of the heterotrophic acidophileAcidiphiliumin order to obtain insight into the life style of these novel bacteria. Here we report on attempts to undertake a similar study onGallionella-like acidophiles from AMD. Isolates belonging to the familyGallionellaceaeare still restricted to the microaerophilic and neutrophilic iron oxidizersSideroxydansandGallionella. Availability of genomic or metagenomic sequence data of acidophilic strains of these genera should, therefore, be relevant for defining adaptive strategies in pH homeostasis. This is particularly the case since complete genome sequences of the neutrophilic strainsG. capsiferriformansES-2 andS. lithotrophicusES-1 permit the direct comparison of the metabolic capacity of neutrophilic and acidophilic members of the same genus and, thus, the detection of biochemical features that are specific to acidophilic strains to support life under acidic conditions. Isolation attempts undertaken in this study resulted in the microaerophilic enrichment culture ADE-12-1 which, based on 16S rRNA gene sequence analysis, consisted of at least three to four distinctGallionellaceaestrains that appear to be closely related to the neutrophilic iron oxidizerS. lithotrophicusES-1. Key hypotheses inferred from the metabolic reconstruction of the metagenomic sequence data of these acidophilicSideroxydansstrains include the putative role of urea hydrolysis, formate oxidation and cyanophycin decarboxylation in pH homeostasis.
authors.affiliation: Institute of Biological Sciences, Technische Universität Bergakademie Freiberg Freiberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Mühling
authors.affiliation: Georg-August-University Göttingen, Genomic and Applied Microbiology and Göttingen Genomics, Laboratory Göttingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Poehlein
authors.affiliation: Institute of Biological Sciences, Technische Universität Bergakademie Freiberg Freiberg, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Stuhr
authors.affiliation: Institute of Biological Sciences, Technische Universität Bergakademie Freiberg Freiberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Voitel
authors.affiliation: Georg-August-University Göttingen, Genomic and Applied Microbiology and Göttingen Genomics, Laboratory Göttingen, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Daniel
authors.affiliation: Institute of Biological Sciences, Technische Universität Bergakademie Freiberg Freiberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schlömann
keywords: Gallionella; Sideroxydans; acid mine drainage; cyanophycin; iron oxidation; metagenomics; microaerophilic bacteria; pH homeostasis