Isolation and characterization of novel acidophilic archaea

本提案的目的是了解迄今为止不可培养的和最近发现的古细菌的需求和能力，以便在纯培养中培养和表征它们。该提案的重点是被称为ARMAN的嗜酸纳米生物以及aciduliproundum / methanomisiliicoccus群的新成员。ARMAN细胞的细胞体积和核糖体数量可以小于大肠杆菌细胞大小和核糖体含量的2%。这些细胞是自由生活的，含有1兆bp的基因组。到目前为止，他们的生活方式还是个谜。它们有潜力成为杰出的模式生物来研究维持自由活细胞生命所必需的最小设置。在深海热液喷口系统中，酸性深海沉积物是一种普遍存在的铁还原剂。发光甲烷球菌（Methanomassiliicoccus luminyensis）是产甲烷热原菌的首个成员，从人类粪便中分离得到。有趣的是，我们在酸性矿井排水生物膜的缺氧中心发现了与Aciduliprofundum/ methanomisiliicoccus组生物具有84% 16S rRNA序列相似性的古细菌。没有其他栽培物种与我们发现的古细菌更相似。因此，很可能检测到的生物在许多特征上与分离的代表不同。在ARMAN的案例中，我们检测到具有98% 16S rRNA相似性的生物体，我们是迄今为止唯一一个拥有这些迷人生物体富集培养物的群体。为了发现这些微生物的生态位并揭示它们的生理潜力，我们希望将微生物富集、分离和表征技术与生化和生物信息学分析相结合。这些技术的结合将使我们能够进一步了解环境中古细菌的生态位和功能。

It is the aim of this proposal to understand the requirements and capabilities of so far uncultivable and just recently discovered archaea to an extend that allows for their cultivation and characterization in pure culture. In the focus of this proposal are acidophilic nanorganisms which are called ARMAN as well as new members of the Aciduliprofundum/ Methanomissiliicoccus group. The cellular volume and number of ribosomes of an ARMAN cell can be less than 2% of what was shown as size and ribosome content of an E. coli cell. The cells are free-living and contain a 1 Mbp genome. Their lifestyle is so far enigmatic. They have the potential to become outstanding model organisms to study the minimal setup that is necessary to sustain life of free living cells. Aciduliprofundum boonei was shown to be a ubiquitously distributed ferric iron reducer at deep-sea hydrothermal vent systems. Methanomassiliicoccus luminyensis is the first member of methanogenic Thermoplasmatales and was isolated from human faeces. Interestingly, we found in the anoxic center of an acid mine drainage biofilm archaea which share a 84% 16S rRNA sequence similarity to organisms of the Aciduliprofundum/Methanomissiliicoccus group. There is no other cultivated species that would be more similar to the by us discovered archaea. Hence, it is very likely that the detected organisms differ in a multitude of characteristics from isolated representatives. In the case of ARMAN, we detected organisms with 98% 16S rRNA similarity and we are so far the only group that has enrichment cultures of these fascinating organisms. In order to discover the ecological niche of these microbes and to unravel their physiological potential, we want to combine microbiological enrichment, isolation and characterization techniques with biochemical and bioinformatic analyses. The combination of these techniques will allow us to advance our understanding of niches and functions of archaea in the environment.