Sokolova T, Hanel J, Onyenwoke R U, Reysenbach A-L, Banta A, Geyer R, González J M, Whitman W B, Wiegel J
Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312, Moscow, Russia.
Extremophiles. 2007 Jan;11(1):145-57. doi: 10.1007/s00792-006-0022-5. Epub 2006 Oct 5.
Three thermophilic strains of chemolithoautotrophic Fe(III)-reducers were isolated from mixed sediment and water samples (JW/KA-1 and JW/KA-2(T): Calcite Spring, Yellowstone N.P., WY, USA; JW/JH-Fiji-2: Savusavu, Vanu Levu, Fiji). All were Gram stain positive rods (approximately 0.5 x 1.8 microm). Cells occurred singly or in V-shaped pairs, and they formed long chains in complex media. All utilized H(2) to reduce amorphous iron (III) oxide/hydroxide to magnetite at temperatures from 50 to 75 degrees C (opt. approximately 73 degrees C). Growth occurred within the pH(60C) range of 6.5-8.5 (opt. pH(60C) 7.1-7.3). Magnetite production by resting cells occurred at pH(60C) 5.5-10.3 (opt. 7.3). The iron (III) reduction rate was 1.3 mumol Fe(II) produced x h(-1) x ml(-1) in a culture with 3 x 10(7) cells, one of the highest rates reported. In the presence or absence of H(2), JW/KA-2(T) did not utilize CO. The G + C content of the genomic DNA of the type strain is 52.7 +/- 0.3 mol%. Strains JW/KA-1 and JW/KA-2(T) each contain two different 16S rRNA gene sequences. The 16S rRNA gene sequences from JW/KA-1, JW/KA-2(T), or JW/JH-Fiji-2 possessed >99% similarity to each other but also 99% similarity to the 16S rRNA gene sequence from the anaerobic, thermophilic, hydrogenogenic CO-oxidizing bacterium 'Carboxydothermus restrictus' R1. DNA-DNA hybridization between strain JW/KA-2(T) and strain R1(T) yielded 35% similarity. Physiological characteristics and the 16S rRNA gene sequence analysis indicated that the strains represent two novel species and are placed into the novel genus Thermolithobacter within the phylum 'Firmicutes'. In addition, the levels of 16S rRNA gene sequence similarity between the lineage containing the Thermolithobacter and well-established members of the three existing classes of the 'Firmicutes' is less than 85%. Therefore, Thermolithobacter is proposed to constitute the first genus within a novel class of the 'Firmicutes', Thermolithobacteria. The Fe(III)-reducing Thermolithobacter ferrireducens gen. nov., sp. nov. is designated as the type species with strain JW/KA-2(T) (ATCC 700985(T), DSM 13639(T)) as its type strain. Strain R1(T) is the type strain for the hydrogenogenic, CO-oxidizing Thermolithobacter carboxydivorans sp. nov. (DSM 7242(T), VKM 2359(T)).
从混合沉积物和水样中分离出三株嗜热化能自养型铁（III）还原菌（JW/KA - 1和JW/KA - 2(T)：美国怀俄明州黄石国家公园的方解石泉；JW/JH - 斐济 - 2：斐济瓦努阿岛的萨武萨武）。所有菌株均为革兰氏阳性杆菌（约0.5×1.8微米）。细胞单个存在或呈V形成对，在复合培养基中形成长链。所有菌株都利用氢气在50至75摄氏度（最适约73摄氏度）的温度下将无定形铁（III）氧化物/氢氧化物还原为磁铁矿。生长发生在pH（60°C）6.5 - 8.5的范围内（最适pH（60°C）7.1 - 7.3）。静止细胞产生磁铁矿的pH（60°C）范围为5.5 - 10.3（最适7.3）。在含有3×10⁷个细胞的培养物中，铁（III）还原速率为1.3微摩尔Fe（II）产生·小时⁻¹·毫升⁻¹，这是报道的最高速率之一。在有或没有氢气存在的情况下，JW/KA - 2(T)都不利用一氧化碳。模式菌株基因组DNA的G + C含量为52.7±0.3摩尔%。菌株JW/KA - 1和JW/KA - 2(T)各自包含两个不同的16S rRNA基因序列。来自JW/KA - 1、JW/KA - 2(T)或JW/JH - 斐济 - 2的16S rRNA基因序列彼此之间具有>99%的相似性，但与厌氧、嗜热、产氢一氧化碳氧化细菌“严格羧热菌”R1的16S rRNA基因序列也有99%的相似性。菌株JW/KA - 2(T)与菌株R1(T)之间的DNA - DNA杂交相似性为35%。生理特征和16S rRNA基因序列分析表明，这些菌株代表两个新物种，并被归入厚壁菌门中的新属嗜热石杆菌属。此外，包含嗜热石杆菌属的谱系与厚壁菌门现有三个类别的已确立成员之间的16S rRNA基因序列相似性水平低于85%。因此，提议嗜热石杆菌属构成厚壁菌门一个新类嗜热石杆菌纲中的第一个属。嗜热铁还原嗜热石杆菌属 新属，新种被指定为模式种，菌株JW/KA - 2(T)（ATCC 700985(T)，DSM 13639(T)）为其模式菌株。菌株R1(T)是产氢一氧化碳氧化嗜热石杆菌新种（DSM 7242(T)，VKM 2359(T)）的模式菌株。
