title: Thermobaculum terrenum gen. nov., sp. nov.: a non-phototrophic gram-positive thermophile representing an environmental clone group related to the Chloroflexi (green non-sulfur bacteria) and Thermomicrobia.
abstract: A novel bacterium was cultivated from an extreme thermal soil in Yellowstone National Park, Wyoming, USA, that at the time of sampling had a pH of 3.9 and a temperature range of 65-92 degrees C. This organism was found to be an obligate aerobic, non-spore-forming rod, and formed pink-colored colonies. Phylogenetic analysis of the 16S rRNA gene sequence placed this organism in a clade composed entirely of environmental clones most closely related to the phyla Chloroflexi and Thermomicrobia. This bacterium stained gram-positive, contained a novel fatty-acid profile, had cell wall muramic acid content similar to that of Bacillus subtilis (significantly greater than Escherichia coli), and failed to display a lipopolysaccharide profile in SDS-polyacrylamide gels that would be indicative of a gram-negative cell wall structure. Ultrastructure examinations with transmission electron microscopy showed a thick cell wall (approximately 34 nm wide) external to a cytoplasmic membrane. The organism was not motile under the culture conditions used, and electron microscopic examination showed no evidence of flagella. Genomic G+C content was 56.4 mol%, and growth was optimal at 67 degrees C and at a pH of 7.0. This organism was able to grow heterotrophically on various carbon compounds, would use only oxygen as an electron acceptor, and its growth was not affected by light. A new species of a novel genus is proposed, with YNP1(T) (T=type strain) being Thermobaculum terrenum gen. nov., sp. nov. (16S rDNA gene GenBank accession AF391972). This bacterium has been deposited in the American Type Culture Collection (ATCC BAA-798) and the University of Oregon Culture Collection of Microorganisms from Extreme Environments (CCMEE 7001).
authors.affiliation: Thermal Biology Institute, Montana State University, Bozeman, MT 59717, USA.
authors.forename: Lina M
authors.initials: LM
authors.lastname: Botero
authors.forename: Kathy B
authors.initials: KB
authors.lastname: Brown
authors.forename: Sue
authors.initials: S
authors.lastname: Brumefield
authors.forename: Mark
authors.initials: M
authors.lastname: Burr
authors.forename: Richard W
authors.initials: RW
authors.lastname: Castenholz
authors.forename: Mark
authors.initials: M
authors.lastname: Young
authors.forename: Timothy R
authors.initials: TR
authors.lastname: McDermott
mesh_terms: D001482:Base Composition; D041862:Chloroflexi / Q000145:classification / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D008854:Microscopy, Electron; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012988:Soil Microbiology; D013696:Temperature
chemical_list: D012336:RNA, Ribosomal, 16S