title: Characterization of Aquamicrobium defluvii gen. nov. sp. nov., a thiophene-2-carboxylate-metabolizing bacterium from activated sludge.
abstract: A gram-negative bacterium was isolated from activated sewage sludge with thiophene-2-carboxylate as the sole source of carbon and with nitrate as an electron acceptor. The isolate, strain NKK, was a motile, oxidase- and catalase-positive, rod-like bacterium with a G+C content of 61.7 mol%. Besides nitrate, oxygen could serve as a terminal electron acceptor. Among many carbon sources tested, only a few sugars, fatty acids, and thiophene-2-carboxylate supported growth. Other heterocyclic compounds were not used. The sulfur atom of thiophene-2-carboxylate was oxidized to thiosulfate when cells were grown aerobically, or to elemental sulfur when cells were grown anaerobically with nitrate. Nitrate was reduced to nitrite. Growth on thiophene-2-carboxylate was dependent on the addition of molybdate to the medium. Tungstate, a specific antagonist of molybdate, inhibited growth on thiophene-2-carboxylate at concentrations > 10(-7) M. Three inducible enzymes involved in the metabolism of thiophene-2-carboxylate were detected: an ATP-, CoA-, thiophene-2-carboxylate- and Mg2+-dependent thiophene-2-carboxyl-CoA ligase (AMP-forming), a molybdenum-containing thiophene-2-carboxyl-CoA dehydrogenase, and a thiophene-2-carboxyl-CoA thioesterase. The sequence of the 16S rRNA gene suggested a classification of strain NKK within the alpha-subgroup of the Proteobacteria as a new genus and species, Aquamicrobium defluvii gen. nov. sp. nov. (DSM 11603), closely related to Mesorhizobium sp. and Phyllobacterium sp., but representing a distinct lineage equal in depth to those of the two mentioned genera. Aquamicrobium defluvii can be distinguished from both genera by a distinct spectrum of substrates, the maximal growth temperature, and a different salt tolerance.
authors.affiliation: Institut für Ingenieurbiologie und Biotechnologie des Abwassers, Universität Karlsruhe, Am Fasanengarten, D-76128 Karlsruhe, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Bambauer
authors.forename: F A
authors.initials: FA
authors.lastname: Rainey
authors.forename: E
authors.initials: E
authors.lastname: Stackebrandt
authors.forename: J
authors.initials: J
authors.lastname: Winter
mesh_terms: D002264:Carboxylic Acids; D002455:Cell Division / Q000187:drug effects; D003066:Coenzyme A Ligases / Q000187:drug effects / Q000378:metabolism; D004275:DNA, Ribosomal / Q000032:analysis / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008828:Microbiological Techniques; D008982:Molybdenum / Q000494:pharmacology; D010170:Palmitoyl-CoA Hydrolase / Q000187:drug effects / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000382:microbiology*; D012988:Soil Microbiology; D013876:Thiophenes / Q000378:metabolism* / Q000494:pharmacology; D017973:Tungsten Compounds / Q000494:pharmacology
chemical_list: D002264:Carboxylic Acids; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D013876:Thiophenes; D017973:Tungsten Compounds; C044659:molybdate; C550746:2-thiophene carboxylic acid; D008982:Molybdenum; D010170:Palmitoyl-CoA Hydrolase; D003066:Coenzyme A Ligases; C045951:tungstate