Emergent complexity of microbial communities in the planetary crust

Microbial communities are highly complex systems, yet are assembled from basic building blocks of some of the simplest organisms on Earth. We currently have ample information on many individual microbial taxa, but we lack fundamental understanding of how complexity emerges as microbial communities are assembled. As microorganisms almost always exist in complex communities, a series of experiments were implemented in order to study the factors involved in community assembly. Here, focus was placed on investigating two assembly processes described by the metacommunity concept: neutral assembly, dominated by stochastic processes, and species sorting, where the environment selects for the emerging complex community. The process of assembling a complex microbial community on different rock substrates was studied in a series of interlinked experiments. In an experiment examining colonisation of two end-member igneous rock types over the course of 1.5 years, it was hypothesised that neutral processes would dominate at the outset, with environmental selection and thus species sorting becoming more important with time. The results indicate that the opposite is true: the communities are selected for at the outset and converge through neutral processes to a more complex community as the environments become more similar over time. Other experiments were set up in order to probe different factors controlling the assembly of complex microbial communities. Microbial environmental engineering was studied by investigating microbially-mediated rock weathering and its effect on the emerging community. The role of priority effects in building a complex community from simple building blocks was investigated using strains isolated from the colonisation experiment, by mixing together single isolates with some time lag into a co-culture. Lastly, the impact of environmental perturbation on viability of communities at different stages in the assembly process was studied using stresses such as freeze-thaw and desiccation. Together, these experiments have given greater insight into the various factors that influence the assembly of a complex microbial community

A Low-Diversity Microbiota Inhabits Extreme Terrestrial Basaltic Terrains and Their Fumaroles : Implications for the Exploration of Mars

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.Peer reviewe

The UK Centre for Astrobiology:A Virtual Astrobiology Centre. Accomplishments and Lessons Learned, 2011-2016

Authors thank all those individuals, UK research councils, funding agencies, nonprofit organisations, companies and corporations and UK and non-UK government agencies, who have so generously supported our aspirations and hopes over the last 5 years and supported UKCA projects. They include the STFC, the Engineering and Physical Sciences Research Council (EPSRC), the Natural Environmental Research Council (NERC), the EU, the UK Space Agency, NASA, the European Space Agency (ESA), The Crown Estate, Cleveland Potash and others. The Astrobiology Academy has been supported by the UK Space Agency (UKSA), National Space Centre, the Science and Technology Facilities Council (STFC), Dynamic Earth, The Royal Astronomical Society, The Rotary Club (Shetlands) and the NASA Astrobiology Institute.The UK Centre for Astrobiology (UKCA) was set up in 2011 as a virtual center to contribute to astrobiology research, education, and outreach. After 5 years, we describe this center and its work in each of these areas. Its research has focused on studying life in extreme environments, the limits of life on Earth, and implications for habitability elsewhere. Among its research infrastructure projects, UKCA has assembled an underground astrobiology laboratory that has hosted a deep subsurface planetary analog program, and it has developed new flow-through systems to study extraterrestrial aqueous environments. UKCA has used this research backdrop to develop education programs in astrobiology, including a massive open online course in astrobiology that has attracted over 120,000 students, a teacher training program, and an initiative to take astrobiology into prisons. In this paper, we review these activities and others with a particular focus on providing lessons to others who may consider setting up an astrobiology center, institute, or science facility. We discuss experience in integrating astrobiology research into teaching and education activities.Publisher PDFPeer reviewe

The total DNA content in the biosphere

<p>The total DNA content in the biosphere</p

Storing the total amount of information encoded in DNA in the biosphere, 5.3 × 10³¹ megabases (Mb), would require approximately 10²¹ supercomputers with the average storage capacity of the world’s four most powerful supercomputers.

<p>Image credit: Globe from NASA, Wikimedia Commons; Composite Fig. 1 created by David Hammett.</p