Microbial Ecology of Fe (hydr)oxide Mats and Basaltic Rock from Vailulu'u Seamount, American Samoa

Sudek, Lisa; Templeton, Alexis S.; Tebo, Bradley M.; Staudigel, Hubert

doi:10.1080/01490450903263400

Cited by 73 publications

(66 citation statements)

References 62 publications

(105 reference statements)

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“…These are the first deep-sequencing results for seafloor basalts. Previous studies have illustrated that basalts are host to diverse and abundant microbial communities dominated by bacteria (2,4,27,(61)(62)(63)(64). Pyrotag sequencing of the V6 hypervariable region of 16S rRNA supports earlier findings that Gammaproteobacteria are the most abundant bacterial class on seafloor basalts and that the Chromatiales and Thiotrichales orders of sulfur-oxidizing bacteria are among the basalt-associated Gammaproteobacteria (2,4,62).…”

supporting

confidence: 72%

Extracellular Enzyme Activity and Microbial Diversity Measured on Seafloor Exposed Basalts from Loihi Seamount Indicate the Importance of Basalts to Global Biogeochemical Cycling

Meyers

Sylvan

Edwards

2014

Appl Environ Microbiol

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Seafloor basalts are widely distributed and host diverse prokaryotic communities, but no data exist concerning the metabolic rates of the resident microbial communities. We present here potential extracellular enzyme activities of leucine aminopeptidase (LAP) and alkaline phosphatase (AP) measured on basalt samples from different locations on Loihi Seamount, HI, coupled with analysis of prokaryotic biomass and pyrosequencing of the bacterial 16S rRNA gene. The community maximum potential enzyme activity (V max ) of LAP ranged from 0.47 to 0.90 nmol (g rock) ؊1 h ؊1 ; the V max for AP was 28 to 60 nmol (g rock) ؊1 h ؊1 . The K m of LAP ranged from 26 to 33 M, while the K m for AP was 2 to 7 M. Bacterial communities on Loihi basalts were comprised primarily of Alpha-, Delta-, andGammaproteobacteria, Bacteroidetes, and Planctomycetes. The putative ability to produce LAP is evenly distributed across the most commonly detected bacterial orders, but the ability to produce AP is likely dominated by bacteria in the orders Xanthomonadales, Flavobacteriales, and Planctomycetales. The enzyme activities on Loihi basalts were compared to those of other marine environments that have been studied and were found to be similar in magnitude to those from continental shelf sediments and orders of magnitude higher than any measured in the water column, demonstrating that the potential for exposed basalts to transform organic matter is substantial. We propose that microbial communities on basaltic rock play a significant, quantifiable role in benthic biogeochemical processes. Exposed seafloor basalts comprise a 600,000-km 2 continuous undersea habitat (1). Endolithic basalt microbes are diverse and abundant (2), and several clades of bacteria appear more likely to be encountered on basalts than elsewhere (3). Bacterial phyla display trends in abundance that reflect rock geochemistry, indicating a strong selection of microbial communities by rock composition (4). Genes diagnostic for methanogenesis, nitrogen fixation, anaerobic ammonium oxidation, denitrification, Fe reduction, and dissimilatory sulfate reduction are present in basalt microbial communities (3), indicating the potential for diverse biogeochemical transformations on basalts. However, no data are currently available for metabolic activity rates of basaltic microbes.The relationship between the presence of prokaryotes and the activity and function of enzymes in extreme environments in general and basalts in particular is underexplored. Hydrolytic extracellular enzymes have been shown to be indicators of metabolically active bacteria, and existing data sets from various marine environments can be used for comparison with information from newly explored areas (5, 6). Additionally, in deep sea environments, organic matter is more refractory in nature, and therefore, extracellular enzyme hydrolases should play an important role in the initiation of organic matter recycling. Indeed, recent work showed that the most abundant group of Archaea in marine sediments produces unique...

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supporting

confidence: 72%

Extracellular Enzyme Activity and Microbial Diversity Measured on Seafloor Exposed Basalts from Loihi Seamount Indicate the Importance of Basalts to Global Biogeochemical Cycling

Meyers

Sylvan

Edwards

2014

Appl Environ Microbiol

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“…5D) (479). Additional studies have confirmed colonization of fresh mineral surfaces by microorganisms (133,425,517,540). Further support for microbial activity in crustal materials derives from the observation of conspicuous "tubes" that are observed in basalt glasses, which are hypothesized to be generated by microorganisms growing into the surfaces of minerals (162,163,178,179,188).…”

mentioning

confidence: 93%

“…This has resulted in the isolation of novel, autotrophic Fe-oxidizing Gammaproteobacteria (134) and diverse Mn-oxidizing bacteria (541). The isolated Mn-oxidizing bacteria were all Alpha-or Gammaproteobacteria, as were most of the Mn-oxidizing isolates grown from a Vailulu'u Seamount basalt (517). Interestingly, many of the isolates from the Vailulu'u Seamount were capable of both Fe and Mn oxidation.…”

Section: Cultivated Prokaryotes From the Dark Oceanmentioning

confidence: 99%

“…Within the other detected phyla, the function of the observed species is poorly understood. Furthermore, the microorganisms responsible for iron oxidation in this environment are not obvious, as known marine Fe-oxidizing bacteria (i.e., Zetaproteobacteria) are rarely recovered in 16S rRNA gene clone libraries, although recent studies have enriched microorganisms from basalts that produce siderophores, enzymes involved in metal cycling (517).…”

mentioning

confidence: 99%

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Microbial Ecology of the Dark Ocean above, at, and below the Seafloor

Orcutt

Sylvan

Knab

et al. 2011

Microbiol Mol Biol Rev

593

499

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SUMMARY The majority of life on Earth—notably, microbial life—occurs in places that do not receive sunlight, with the habitats of the oceans being the largest of these reservoirs. Sunlight penetrates only a few tens to hundreds of meters into the ocean, resulting in large-scale microbial ecosystems that function in the dark. Our knowledge of microbial processes in the dark ocean—the aphotic pelagic ocean, sediments, oceanic crust, hydrothermal vents, etc.—has increased substantially in recent decades. Studies that try to decipher the activity of microorganisms in the dark ocean, where we cannot easily observe them, are yielding paradigm-shifting discoveries that are fundamentally changing our understanding of the role of the dark ocean in the global Earth system and its biogeochemical cycles. New generations of researchers and experimental tools have emerged, in the last decade in particular, owing to dedicated research programs to explore the dark ocean biosphere. This review focuses on our current understanding of microbiology in the dark ocean, outlining salient features of various habitats and discussing known and still unexplored types of microbial metabolism and their consequences in global biogeochemical cycling. We also focus on patterns of microbial diversity in the dark ocean and on processes and communities that are characteristic of the different habitats.

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“…These were psychrophilic facultative anaerobes that were related to alphaproteobacteria and gammaproteobacteria. More recently, Sudek et al (2009) reported that heterotrophic Pseudomonas/Pseudoalteromonas-like gammaproteobacteria isolated from a volcanic seamount could also catalyse ferrous iron oxidation under micro-aerobic conditions, and therefore contribute to the formation of iron mats in the deep oceans.…”

Section: Neutrophilic Aerobic Iron-oxidizing Proteobacteriamentioning

confidence: 99%

The iron-oxidizing proteobacteria

2011

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The ‘iron bacteria’ are a collection of morphologically and phylogenetically heterogeneous prokaryotes. They include some of the first micro-organisms to be observed and described, and continue to be the subject of a considerable body of fundamental and applied microbiological research. While species of iron-oxidizing bacteria can be found in many different phyla, most are affiliated with the Proteobacteria. The latter can be subdivided into four main physiological groups: (i) acidophilic, aerobic iron oxidizers; (ii) neutrophilic, aerobic iron oxidizers; (iii) neutrophilic, anaerobic (nitrate-dependent) iron oxidizers; and (iv) anaerobic photosynthetic iron oxidizers. Some species (mostly acidophiles) can reduce ferric iron as well as oxidize ferrous iron, depending on prevailing environmental conditions. This review describes what is currently known about the phylogenetic and physiological diversity of the iron-oxidizing proteobacteria, their significance in the environment (on the global and micro scales), and their increasing importance in biotechnology.

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Microbial Ecology of Fe (hydr)oxide Mats and Basaltic Rock from Vailulu'u Seamount, American Samoa

Cited by 73 publications

References 62 publications

Extracellular Enzyme Activity and Microbial Diversity Measured on Seafloor Exposed Basalts from Loihi Seamount Indicate the Importance of Basalts to Global Biogeochemical Cycling

Extracellular Enzyme Activity and Microbial Diversity Measured on Seafloor Exposed Basalts from Loihi Seamount Indicate the Importance of Basalts to Global Biogeochemical Cycling

Microbial Ecology of the Dark Ocean above, at, and below the Seafloor

The iron-oxidizing proteobacteria

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