title: Genome Sequence ofDesulfurella amilsiiStrain TR1 and Comparative Genomics ofDesulfurellaceaeFamily.
abstract: The acidotolerant sulfur reducerDesulfurella amilsiiwas isolated from sediments of Tinto River, an extremely acidic environment. Its ability to grow in a broad range of pH and to tolerate certain heavy metals offers potential for metal recovery processes. Here we report its high-quality draft genome sequence and compare it to the available genome sequences of other members ofDesulfurellaceaefamily:D. acetivorans. D. multipotens, Hippea maritima. H. alviniae, H. medeae, andH. jasoniae. For most species, pairwise comparisons for average nucleotide identity (ANI) andin silicoDNA-DNA hybridization (DDH) revealed ANI values from 67.5 to 80% and DDH values from 12.9 to 24.2%.D. acetivoransandD. multipotens, however, surpassed the estimated thresholds of species definition for both DDH (98.6%) and ANI (88.1%). Therefore, they should be merged to a single species. Comparative analysis ofDesulfurellaceaegenomes revealed different gene content for sulfur respiration betweenDesulfurellaandHippeaspecies. Sulfur reductase is only encoded inD. amilsii, in which it is suggested to play a role in sulfur respiration, especially at low pH. Polysulfide reductase is only encoded inHippeaspecies; it is likely that this genus uses polysulfide as electron acceptor. Genes encoding thiosulfate reductase are present in all the genomes, but dissimilatory sulfite reductase is only present inDesulfurellaspecies. Thus, thiosulfate respiration via sulfite is only likely in this genus. Although sulfur disproportionation occurs inDesulfurellaspecies, the molecular mechanism behind this process is not yet understood, hampering a genome prediction. The metabolism of acetate inDesulfurellaspecies can occur via the acetyl-CoA synthetase or via acetate kinase in combination with phosphate acetyltransferase, while inHippeaspecies, it might occur via the acetate kinase. Large differences in gene sets involved in resistance to acidic conditions were not detected among the genomes. Therefore, the regulation of those genes, or a mechanism not yet known, might be responsible for the unique ability ofD. amilsii. This is the first report on comparative genomics of sulfur-reducing bacteria, which is valuable to give insight into this poorly understood metabolism, but of great potential for biotechnological purposes and of environmental significance.
authors.affiliation: Laboratory of Microbiology, Wageningen UniversityWageningen, Netherlands; Sub-department of Environmental Technology, Wageningen UniversityWageningen, Netherlands.
authors.forename: Anna P
authors.initials: AP
authors.lastname: Florentino
authors.affiliation: Laboratory of Microbiology, Wageningen UniversityWageningen, Netherlands; Centre of Biological Engineering, University of MinhoBraga, Portugal.
authors.forename: Alfons J M
authors.initials: AJ
authors.lastname: Stams
authors.affiliation: Laboratory of Microbiology, Wageningen University Wageningen, Netherlands.
authors.forename: Irene
authors.initials: I
authors.lastname: Sánchez-Andrea
keywords: Desulfurellaceae; acidophiles; comparative genomics; metabolism; sulfur reducers