Soudan地下矿山州立公园,在明尼苏达州北部的朱红色铁场发现,提供了一个~27亿年的带状铁地层。1958年至1962年之间在该矿的第27层(地下713m)上钻探的探索性钻孔与最近经过宏基因组分析和微生物富集的富含钙和铁的盐水相交。使用从深达55m的钻孔泵送的浓缩盐水样品,一种新的革兰氏阳性菌在厌氧条件下富集,醋酸盐氧化,和Fe(III)柠檬酸盐还原条件。分离出的细菌,指定菌株MK1,不运动,杆状,孢子形成,厌氧,嗜温,生长范围在24°C至30°C之间。发现完整的环状MK1基因组为3,720,236bp,编码25个推定的多血红素细胞色素,包括革兰氏阴性菌gobacter硫还原菌的内膜细胞色素的同系物和革兰氏阳性菌Thermincolaotils的细胞质膜和周质细胞色素。然而,MK1不编码肽聚糖(CwcA)和细胞表面相关(OcwA)多血红素细胞色素的同系物,这被认为是T.otrops进行细胞外电子转移所必需的。MK1的16SrRNA基因序列表明,其最密切相关的分离株是耐碱性脱硫杆菌sk。kt5(91%序列同一性),将MK1置于脱硫杆菌科和Moorellales科内的一个新属中。在Moorellales命令中,据报道,只有Calderihistansmaritimus菌株KKC1会减少Fe(III),只有耐碱D.也可以在低于40°C的温度下生长。因此,MK1代表一个新属中的新物种,为此,我们建议将其命名为“Metallumcolaferriviriculae”菌株MK1,并提供了研究富含细胞色素的独特机会,嗜温,革兰氏阳性,形成孢子的Fe(III)还原细菌。重要信息Soudan地下矿山州立公园可进入深地面地下未研究的区域,这些区域可能早于大氧化事件。研究那些相对不受地表条件干扰长达27亿年的生物,可能会让我们在氧气主导地球之前进入古代生命的窗口。此外,研究缺氧和富铁环境中的微生物可以帮助我们更好地了解类似环境中的生命需求,比如在火星上。“Metallumcolaferriviriculae”菌株MK1的分离和鉴定使我们了解了一个新的属和物种,该属和物种与其最接近的分离株和迄今为止表征的铁还原剂都不同。\"M.MK1菌株也可以作为模型生物来研究孢子形成和萌发过程如何受到不溶性细胞外受体的影响,以及孢子对地球深层生物圈的影响。
The Soudan Underground Mine State Park, found in the Vermilion Iron Range in northern Minnesota, provides access to a ~ 2.7 billion-year-old banded iron formation. Exploratory boreholes drilled between 1958 and 1962 on the 27th level (713 m underground) of the mine intersect calcium and iron-rich brines that have recently been subject to metagenomic analysis and microbial enrichments. Using concentrated brine samples pumped from a borehole depth of up to 55 m, a novel Gram-positive bacterium was enriched under anaerobic, acetate-oxidizing, and Fe(III) citrate-reducing conditions. The isolated bacterium, designated strain MK1, is non-motile, rod-shaped, spore-forming, anaerobic, and mesophilic, with a growth range between 24°C and 30°C. The complete circular MK1 genome was found to be 3,720,236 bp and encodes 25 putative multiheme cytochromes, including homologs to inner membrane cytochromes in the Gram-negative bacterium Geobacter sulfurreducens and cytoplasmic membrane and periplasmic cytochromes in the Gram-positive bacterium Thermincola potens. However, MK1 does not encode homologs of the peptidoglycan (CwcA) and cell surface-associated (OcwA) multiheme cytochromes proposed to be required by T. potens to perform extracellular electron transfer. The 16S rRNA gene sequence of MK1 indicates that its closest related isolate is Desulfitibacter alkalitolerans strain sk.kt5 (91% sequence identity), which places MK1 in a novel genus within the Desulfitibacteraceae family and Moorellales order. Within the Moorellales order, only Calderihabitans maritimus strain KKC1 has been reported to reduce Fe(III), and only D. alkalitolerans can also grow in temperatures below 40°C. Thus, MK1 represents a novel species within a novel genus, for which we propose the name \"Metallumcola ferriviriculae\" strain MK1, and provides a unique opportunity to study a cytochrome-rich, mesophilic, Gram-positive, spore-forming Fe(III)-reducing bacterium.IMPORTANCEThe Soudan Underground Mine State Park gives access to understudied regions of the deep terrestrial subsurface that potentially predate the Great Oxidation Event. Studying organisms that have been relatively unperturbed by surface conditions for as long as 2.7 billion years may give us a window into ancient life before oxygen dominated the planet. Additionally, studying microbes from anoxic and iron-rich environments can help us better understand the requirements of life in analogous environments, such as on Mars. The isolation and characterization of \"Metallumcola ferriviriculae\" strain MK1 give us insights into a novel genus and species that is distinct both from its closest related isolates and from iron reducers characterized to date. \"M. ferriviriculae\" strain MK1 may also act as a model organism to study how the processes of sporulation and germination are affected by insoluble extracellular acceptors, as well as the impact of spores in the deep terrestrial biosphere.