Kashefi Kazem, Holmes Dawn E, Baross John A, Lovley Derek R
Department of Microbiology, University of Massachusetts, 203 Morrill Science Center IVN, Amherst, MA 01003, USA.
Appl Environ Microbiol. 2003 May;69(5):2985-93. doi: 10.1128/AEM.69.5.2985-2993.2003.
Little is known about the microbiology of the "Bag City" hydrothermal vent, which is part of a new eruption site on the Juan de Fuca Ridge and which is notable for its accumulation of polysaccharide on the sediment surface. A pure culture, designated strain SS015, was recovered from a vent fluid sample from the Bag City site through serial dilution in liquid medium with malate as the electron donor and Fe(III) oxide as the electron acceptor and then isolation of single colonies on solid Fe(III) oxide medium. The cells were gram-negative rods, about 0.5 micro m by 1.2 to 1.5 micro m, and motile and contained c-type cytochromes. Analysis of the 16S ribosomal DNA (rDNA) sequence of strain SS015 placed it in the family Geobacteraceae in the delta subclass of the Proteobacteria. Unlike previously described members of the Geobacteraceae, which are mesophiles, strain SS015 was a thermophile and grew at temperatures of between 35 and 65 degrees C, with an optimum temperature of 55 degrees C. Like many previously described members of the Geobacteraceae, strain SS015 grew with organic acids as the electron donors and Fe(III) or nitrate as the electron acceptor, with nitrate being reduced to ammonia. Strain SS015 was unique among the Geobacteraceae in its ability to use sugars, starch, or amino acids as electron donors for Fe(III) reduction. Under stress conditions, strain SS015 produced copious quantities of extracellular polysaccharide, providing a model for the microbial production of the polysaccharide accumulation at the Bag City site. The 16S rDNA sequence of strain SS015 was less than 94% similar to the sequences of previously described members of the Geobacteraceae; this fact, coupled with its unique physiological properties, suggests that strain SS015 represents a new genus in the family Geobacteraceae. The name Geothermobacter ehrlichii gen. nov., sp. nov., is proposed (ATCC BAA-635 and DSM 15274). Although strains of Geobacteraceae are known to be the predominant Fe(III)-reducing microorganisms in a variety of Fe(III)-reducing environments at moderate temperatures, strain SS015 represents the first described thermophilic member of the Geobacteraceae and thus extends the known environmental range of this family to hydrothermal environments.
关于“袋城”热液喷口的微生物学情况所知甚少，该热液喷口是胡安德富卡海岭一处新的火山喷发地点的一部分，以其沉积物表面多糖的积累而闻名。通过在以苹果酸盐作为电子供体、氧化铁（III）作为电子受体的液体培养基中进行连续稀释，然后在固体氧化铁（III）培养基上分离单菌落，从袋城地点的一个喷口流体样本中获得了一种纯培养物，命名为菌株SS015。这些细胞为革兰氏阴性杆菌，大小约为0.5微米×1.2至1.5微米，具有运动性且含有c型细胞色素。对菌株SS015的16S核糖体DNA（rDNA）序列分析表明，它属于变形菌纲δ亚纲地杆菌科。与先前描述的地杆菌科成员不同，它们是嗜温菌，而菌株SS015是嗜热菌，能在35至65摄氏度的温度下生长，最适温度为55摄氏度。与许多先前描述的地杆菌科成员一样，菌株SS015以有机酸作为电子供体，以氧化铁（III）或硝酸盐作为电子受体，硝酸盐被还原为氨。菌株SS015在地杆菌科中独一无二的能力是能够利用糖、淀粉或氨基酸作为还原氧化铁（III）的电子供体。在应激条件下，菌株SS015会产生大量胞外多糖，为袋城地点微生物产生多糖积累提供了一个模型。菌株SS015的16S rDNA序列与先前描述的地杆菌科成员的序列相似度不到94%；这一事实，再加上其独特的生理特性表明，菌株SS015代表了地杆菌科中的一个新属。提议将其命名为嗜地热杆菌（Geothermobacter ehrlichii），新属，新种（ATCC BAA - 635和DSM 15274）。虽然已知地杆菌科菌株是各种中等温度下的铁（III）还原环境中主要的铁（III）还原微生物，但菌株SS015代表了首次描述的地杆菌科嗜热成员，从而将该科已知的环境范围扩展到了热液环境。
