Isolation and characterization of novel acidophilic archaea

• Applicants: Professor Dr. Johannes Gescher; Professorin Dr. Alice C. McHardy
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 252014092

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.

• DFG Programme: Research Grants