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Project Reports

• Iron Oxidation – Shaping the Past and Present Environments

  This year the Edwards Lab completed and published most outstanding results from her NAI projects. Of notable success was the completion of several aspects concerning the abundance and diversity of life on basaltic rocks, including several methods-based studies that examine in detail the biases associated with different approaches used by ourselves, and in other labs as reported in the literature (Santelli et al., 2008; Orcutt et al., in review, Wang and Edwards, in review). The publication by Santelli et al. in Nature resulted in considerable publicity including and NSF press release and associated artists rendition of microbial life on rocks in the deep sea (Fig. 1).

  ROADMAP OBJECTIVES: 6.1

• Microbial Communities and Activities in the Deep Marine Subsurface

  Novel and unexplored microorganisms thrive in deeply buried marine sediments hundreds of meters below the sea bottom. They extend the domain of life into these energy-starved deep sediments and into the underlying ocean crust. These organisms play essential roles in the microbial cycling of carbon in the deep subsurface. We are exploring their biodiversity, their genetic and physiological repertoire, their role in the ocean ecosystem, and their potential as analogs for extraterrestrial life (see Fig. 1)

  ROADMAP OBJECTIVES: 5.1 5.3 6.1 6.2

• Microbial Diversity and Population Structure Studies in the Rio Tinto

  As part of our Microbial diversity and population structure studies in the Rio Tinto, we hope to better understand how environmental conditions such as pH and metal concentrations help shape the underlying microbial community structures in extreme environments that serve as terrestrial analogs for Mars. The iron-based mineralogy found in the Rio Tinto coupled with low pH are two characteristics that tie this extreme environment to Mars. To this end, we have been sampling stations along the river that differ in the concentration and oxidation state of iron and other metals (see http://amarallab.mbl.edu/rt_main/rt.html for more detailed information and photographs of the study locations) and using molecular techniques coupled with physicochemical measurements to investigate microbial diversity in the water column at both spatial and temporal scales. When possible, determination of as many in situ physico-chemical parameters are made on biofilms as well, using microelectrodes available for field measurements. This allows for the correlation of biological diversity information with physicochemical parameters of the river. The outcome of this study will provide a comprehensive view of the microbial ecology of the system, a first step towards establishing an ecological genomics project for the Rio Tinto.

  ROADMAP OBJECTIVES: 3.3 5.1 5.2

• Describing the Anaerobic Thermophilic Microbial Community: A Metagenomic Strategy

  The ocean is one of the least explored parts of the microbial world, including at deep-sea hydrothermal vents, where the unique geochemistry creates many habitats for microbial and animal communities. These organisms encounter many conditions that we humans consider too extreme- too hot, too toxic, too little oxygen- but microbes seem to find a way and continue to push the limits of life. An impetus for studying life at deep-sea hydrothermal vents is that life may have originated and evolved near hydrothermal systems, and that organisms currently living in these likely analogues of early habitats may still harbor characteristics of early life. In addition, microbes unique to the hydrothermal vents could provide insight into metabolic processes, strategies for growth, and survival of life on solar bodies with a water history, such as Mars and Jupiter’s moon Europa. Our research on diffuse flow vents at deep-sea hydrothermal seamounts provides insight into the diversity, physiology, and genetic potential of these unique microbial communities within the context of their dynamic and complex geochemical habitat.

  ROADMAP OBJECTIVES: 4.1 5.1 5.2

• Genome-Genome Integration: Symbiosis, Genetic Assimilation, and Evolutionary Innovation

  Unlike single mutations, genome interactions can catalyze the acquisition of entirely new combinations of functions and drive major evolutionary transitions. Through studies of binary interactions between two species – i.e. a symbiont and its host- we can dissect the mechanisms of genome communication and coevolution. Through a comparative genomic approach, we are deciphering the 'language’ used to establish and maintain intimate associations between bacteria and animal hosts. Our ultimate objective is to understand how such interactions have contributed to organismal complexity and evolutionary novelty.

  ROADMAP OBJECTIVES: 5.1 5.2 6.2

• Recognition of Theoretical Environments on Mars

  Our goal is to develop remotely sensed signatures that provide guideposts to analyzing remotely sensed data from Mars to explore for habitable environments. We are working with the biologically diverse, iron-rich environments of Rio Tinto and their mineral deposits to develop strategies for interpreting data from Mars.

  ROADMAP OBJECTIVES: 2.1 7.1