Edwards KJ, Rogers DR, Wirsen CO, McCollom TM.
Isolation and Characterization of Novel Psychrophilic, Neutrophilic, Fe-Oxidizing, Chemolithoautotrophic {alpha}- and {gamma}-Proteobacteria from the Deep Sea. Appl. Environ. Microbiol. 2003;69 :2906-2913.
Publisher's VersionAbstractWe report the isolation and physiological characterization of novel, psychrophilic, iron-oxidizing bacteria (FeOB) from low-temperature weathering habitats in the vicinity of the Juan de Fuca deep-sea hydrothermal area. The FeOB were cultured from the surfaces of weathered rock and metalliferous sediments. They are capable of growth on a variety of natural and synthetic solid rock and mineral substrates, such as pyrite (FeS2), basalt glass ([~]10 wt% FeO), and siderite (FeCO3), as their sole energy source, as well as numerous aqueous Fe substrates. Growth temperature characteristics correspond to the in situ environmental conditions of sample origin; the FeOB grow optimally at 3 to 10{degrees}C and at generation times ranging from 57 to 74 h. They are obligate chemolithoautotrophs and grow optimally under microaerobic conditions in the presence of an oxygen gradient or anaerobically in the presence of nitrate. None of the strains are capable of using any organic or alternate inorganic substrates tested. The bacteria are phylogenetically diverse and have no close Fe-oxidizing or autotrophic relatives represented in pure culture. One group of isolates are {gamma}-Proteobacteria most closely related to the heterotrophic bacterium Marinobacter aquaeolei (87 to 94% sequence similarity). A second group of isolates are {alpha}-Proteobacteria most closely related to the deep-sea heterotrophic bacterium Hyphomonas jannaschiana (81 to 89% sequence similarity). This study provides further evidence for the evolutionarily widespread capacity for Fe oxidation among bacteria and suggests that FeOB may play an unrecognized geomicrobiological role in rock weathering in the deep sea.
Visscher PT, Baumgartner LK, Buckley DH, Rogers DR, Hogan ME, Raleigh CD, Turk KA, Marais DDJ.
Dimethyl sulphide and methanethiol formation in microbial mats: potential pathways for biogenic signatures. Environ Microbiol. 2003;5 :296-308.
Publisher's VersionAbstractn/a
Edwards KJ, Bach W, Rogers DR.
Geomicrobiology of the Ocean Crust: A Role for Chemoautotrophic Fe-Bacteria. Biol Bull. 2003;204 :180-185.
Publisher's VersionAbstractThe delicate balance of the major global biogeochemical cycles greatly depends on the transformation of Earth materials at or near its surface. The formation and degradation of rocks, minerals, and organic matter are pivotal for the balance, maintenance, and future of many of these cycles. Microorganisms also play a crucial role, determining the transformation rates, pathways, and end products of these processes. While most of Earth's crust is oceanic rather than terrestrial, few studies have been conducted on ocean crust transformations, particularly those mediated by endolithic (rock-hosted) microbial communities. The biology and geochemistry of deep-sea and sub-seafloor environments are generally more complicated to study than in terrestrial or near-coastal regimes. As a result, fewer, and more targeted, studies usually homing in on specific sites, are most common. We are studying the role of endolithic microorganisms in weathering seafloor crustal materials, including basaltic glass and sulfide minerals, both in the vicinity of seafloor hydrothermal vents and off-axis at unsedimented (young) ridge flanks. We are using molecular phylogenetic surveys and laboratory culture studies to define the size, diversity, physiology, and distribution of microorganisms in the shallow ocean crust. Our data show that an unexpected diversity of microorganisms directly participate in rock weathering at the seafloor, and imply that endolithic microbial communities contribute to rock, mineral, and carbon transformations.