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Ngugi DK, Blom J, Stepanauskas R, Stingl U. Diversification and niche adaptations of Nitrospina-like bacteria in the polyextreme interfaces of Red Sea brines. ISME JOURNAL 2015; 10:1383-99. [PMID: 26657763 PMCID: PMC5029188 DOI: 10.1038/ismej.2015.214] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 10/05/2015] [Accepted: 10/25/2015] [Indexed: 11/22/2022]
Abstract
Nitrite-oxidizing bacteria (NOB) of the genus Nitrospina have exclusively been found in marine environments. In the brine–seawater interface layer of Atlantis II Deep (Red Sea), Nitrospina-like bacteria constitute up to one-third of the bacterial 16S ribosomal RNA (rRNA) gene sequences. This is much higher compared with that reported in other marine habitats (~10% of all bacteria), and was unexpected because no NOB culture has been observed to grow above 4.0% salinity, presumably due to the low net energy gained from their metabolism that is insufficient for both growth and osmoregulation. Using phylogenetics, single-cell genomics and metagenomic fragment recruitment approaches, we document here that these Nitrospina-like bacteria, designated as Candidatus Nitromaritima RS, are not only highly diverged from the type species Nitrospina gracilis (pairwise genome identity of 69%) but are also ubiquitous in the deeper, highly saline interface layers (up to 11.2% salinity) with temperatures of up to 52 °C. Comparative pan-genome analyses revealed that less than half of the predicted proteome of Ca. Nitromaritima RS is shared with N. gracilis. Interestingly, the capacity for nitrite oxidation is also conserved in both genomes. Although both lack acidic proteomes synonymous with extreme halophiles, the pangenome of Ca. Nitromaritima RS specifically encodes enzymes with osmoregulatory and thermoprotective roles (i.e., ectoine/hydroxyectoine biosynthesis) and of thermodynamic importance (i.e., nitrate and nitrite reductases). Ca. Nitromaritima RS also possesses many hallmark traits of microaerophiles and high-affinity NOB. The abundance of the uncultured Ca. Nitromaritima lineage in marine oxyclines suggests their unrecognized ecological significance in deoxygenated areas of the global ocean.
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Affiliation(s)
- David Kamanda Ngugi
- Red Sea Research Centre, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus Liebig University Giessen, Germany
| | | | - Ulrich Stingl
- Red Sea Research Centre, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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252
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Alissandratos A, Easton CJ. Biocatalysis for the application of CO2 as a chemical feedstock. Beilstein J Org Chem 2015; 11:2370-87. [PMID: 26734087 PMCID: PMC4685893 DOI: 10.3762/bjoc.11.259] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/20/2015] [Indexed: 11/23/2022] Open
Abstract
Biocatalysts, capable of efficiently transforming CO2 into other more reduced forms of carbon, offer sustainable alternatives to current oxidative technologies that rely on diminishing natural fossil-fuel deposits. Enzymes that catalyse CO2 fixation steps in carbon assimilation pathways are promising catalysts for the sustainable transformation of this safe and renewable feedstock into central metabolites. These may be further converted into a wide range of fuels and commodity chemicals, through the multitude of known enzymatic reactions. The required reducing equivalents for the net carbon reductions may be drawn from solar energy, electricity or chemical oxidation, and delivered in vitro or through cellular mechanisms, while enzyme catalysis lowers the activation barriers of the CO2 transformations to make them more energy efficient. The development of technologies that treat CO2-transforming enzymes and other cellular components as modules that may be assembled into synthetic reaction circuits will facilitate the use of CO2 as a renewable chemical feedstock, greatly enabling a sustainable carbon bio-economy.
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Affiliation(s)
| | - Christopher J Easton
- Research School of Chemistry, Australian National University, Canberra ACT 2601, Australia
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253
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He Y, Feng X, Fang J, Zhang Y, Xiao X. Metagenome and Metatranscriptome Revealed a Highly Active and Intensive Sulfur Cycle in an Oil-Immersed Hydrothermal Chimney in Guaymas Basin. Front Microbiol 2015; 6:1236. [PMID: 26617579 PMCID: PMC4639633 DOI: 10.3389/fmicb.2015.01236] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/26/2015] [Indexed: 11/13/2022] Open
Abstract
The hydrothermal vent system is a typical chemosynthetic ecosystem in which microorganisms play essential roles in the geobiochemical cycling. Although it has been well-recognized that the inorganic sulfur compounds are abundant and actively converted through chemosynthetic pathways, the sulfur budget in a hydrothermal vent is poorly characterized due to the complexity of microbial sulfur cycling resulting from the numerous parties involved in the processes. In this study, we performed an integrated metagenomic and metatranscriptomic analysis on a chimney sample from Guaymas Basin to achieve a comprehensive study of each sulfur metabolic pathway and its hosting microorganisms and constructed the microbial sulfur cycle that occurs in the site. Our results clearly illustrated the stratified sulfur oxidation and sulfate reduction at the chimney wall. Besides, sulfur metabolizing is closely interacting with carbon cycles, especially the hydrocarbon degradation process in Guaymas Basin. This work supports that the internal sulfur cycling is intensive and the net sulfur budget is low in the hydrothermal ecosystem.
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Affiliation(s)
- Ying He
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China ; State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University Shanghai, China
| | - Xiaoyuan Feng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Jing Fang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Yu Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China ; State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University Shanghai, China ; Institute of Oceanology, Shanghai Jiao Tong University Shanghai, China
| | - Xiang Xiao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China ; State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University Shanghai, China ; Institute of Oceanology, Shanghai Jiao Tong University Shanghai, China
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254
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Frain KM, Gangl D, Jones A, Zedler JAZ, Robinson C. Protein translocation and thylakoid biogenesis in cyanobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:266-73. [PMID: 26341016 DOI: 10.1016/j.bbabio.2015.08.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/17/2015] [Accepted: 08/31/2015] [Indexed: 10/23/2022]
Abstract
Cyanobacteria exhibit a complex form of membrane differentiation that sets them apart from most bacteria. Many processes take place in the plasma membrane, but photosynthetic light capture, electron transport and ATP synthesis take place in an abundant internal thylakoid membrane. This review considers how this system of subcellular compartmentalisation is maintained, and how proteins are directed towards the various subcompartments--specifically the plasma membrane, periplasm, thylakoid membrane and thylakoid lumen. The involvement of Sec-, Tat- and signal recognition particle- (SRP)-dependent protein targeting pathways is discussed, together with the possible involvement of a so-called 'spontaneous' pathway for the insertion of membrane proteins, previously characterised for chloroplast thylakoid membrane proteins. An intriguing aspect of cyanobacterial cell biology is that most contain only a single set of genes encoding Sec, Tat and SRP components, yet the proteomes of the plasma and thylakoid membranes are very different. The implications for protein sorting mechanisms are considered. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Prof Conrad Mullineaux.
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Affiliation(s)
- Kelly M Frain
- Centre for Molecular Processing, School of Biosciences, University of Kent, Ingram Building, Canterbury, CT2 7NJ, United Kingdom
| | - Doris Gangl
- Centre for Molecular Processing, School of Biosciences, University of Kent, Ingram Building, Canterbury, CT2 7NJ, United Kingdom
| | - Alexander Jones
- Centre for Molecular Processing, School of Biosciences, University of Kent, Ingram Building, Canterbury, CT2 7NJ, United Kingdom
| | - Julie A Z Zedler
- Centre for Molecular Processing, School of Biosciences, University of Kent, Ingram Building, Canterbury, CT2 7NJ, United Kingdom
| | - Colin Robinson
- Centre for Molecular Processing, School of Biosciences, University of Kent, Ingram Building, Canterbury, CT2 7NJ, United Kingdom.
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255
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A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes. Adv Microb Physiol 2015. [PMID: 26210106 DOI: 10.1016/bs.ampbs.2015.05.002] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dissimilatory sulphate reduction is the unifying and defining trait of sulphate-reducing prokaryotes (SRP). In their predominant habitats, sulphate-rich marine sediments, SRP have long been recognized to be major players in the carbon and sulphur cycles. Other, more recently appreciated, ecophysiological roles include activity in the deep biosphere, symbiotic relations, syntrophic associations, human microbiome/health and long-distance electron transfer. SRP include a high diversity of organisms, with large nutritional versatility and broad metabolic capacities, including anaerobic degradation of aromatic compounds and hydrocarbons. Elucidation of novel catabolic capacities as well as progress in the understanding of metabolic and regulatory networks, energy metabolism, evolutionary processes and adaptation to changing environmental conditions has greatly benefited from genomics, functional OMICS approaches and advances in genetic accessibility and biochemical studies. Important biotechnological roles of SRP range from (i) wastewater and off gas treatment, (ii) bioremediation of metals and hydrocarbons and (iii) bioelectrochemistry, to undesired impacts such as (iv) souring in oil reservoirs and other environments, and (v) corrosion of iron and concrete. Here we review recent advances in our understanding of SRPs focusing mainly on works published after 2000. The wealth of publications in this period, covering many diverse areas, is a testimony to the large environmental, biogeochemical and technological relevance of these organisms and how much the field has progressed in these years, although many important questions and applications remain to be explored.
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256
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Marakushev SA, Belonogova OV. The chemical potentials of hydrothermal systems and the formation of coupled modular metabolic pathways. Biophysics (Nagoya-shi) 2015. [DOI: 10.1134/s0006350915040168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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257
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Metagenomic resolution of microbial functions in deep-sea hydrothermal plumes across the Eastern Lau Spreading Center. ISME JOURNAL 2015; 10:225-39. [PMID: 26046257 DOI: 10.1038/ismej.2015.81] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/05/2015] [Accepted: 04/09/2015] [Indexed: 11/08/2022]
Abstract
Microbial processes within deep-sea hydrothermal plumes affect ocean biogeochemistry on global scales. In rising hydrothermal plumes, a combination of microbial metabolism and particle formation processes initiate the transformation of reduced chemicals like hydrogen sulfide, hydrogen, methane, iron, manganese and ammonia that are abundant in hydrothermal vent fluids. Despite the biogeochemical importance of this rising portion of plumes, it is understudied in comparison to neutrally buoyant plumes. Here we use metagenomics and bioenergetic modeling to describe the abundance and genetic potential of microorganisms in relation to available electron donors in five different hydrothermal plumes and three associated background deep-sea waters from the Eastern Lau Spreading Center located in the Western Pacific Ocean. Three hundred and thirty one distinct genomic 'bins' were identified, comprising an estimated 951 genomes of archaea, bacteria, eukarya and viruses. A significant proportion of these genomes is from novel microorganisms and thus reveals insights into the energy metabolism of heretofore unknown microbial groups. Community-wide analyses of genes encoding enzymes that oxidize inorganic energy sources showed that sulfur oxidation was the most abundant and diverse chemolithotrophic microbial metabolism in the community. Genes for sulfur oxidation were commonly present in genomic bins that also contained genes for oxidation of hydrogen and methane, suggesting metabolic versatility in these microbial groups. The relative diversity and abundance of genes encoding hydrogen oxidation was moderate, whereas that of genes for methane and ammonia oxidation was low in comparison to sulfur oxidation. Bioenergetic-thermodynamic modeling supports the metagenomic analyses, showing that oxidation of elemental sulfur with oxygen is the most dominant catabolic reaction in the hydrothermal plumes. We conclude that the energy metabolism of microbial communities inhabiting rising hydrothermal plumes is dictated by the underlying plume chemistry, with a dominant role for sulfur-based chemolithoautotrophy.
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258
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Klatt JM, Polerecky L. Assessment of the stoichiometry and efficiency of CO2 fixation coupled to reduced sulfur oxidation. Front Microbiol 2015; 6:484. [PMID: 26052315 PMCID: PMC4440400 DOI: 10.3389/fmicb.2015.00484] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 05/02/2015] [Indexed: 11/13/2022] Open
Abstract
Chemolithoautotrophic sulfur oxidizing bacteria (SOB) couple the oxidation of reduced sulfur compounds to the production of biomass. Their role in the cycling of carbon, sulfur, oxygen, and nitrogen is, however, difficult to quantify due to the complexity of sulfur oxidation pathways. We describe a generic theoretical framework for linking the stoichiometry and energy conservation efficiency of autotrophic sulfur oxidation while accounting for the partitioning of the reduced sulfur pool between the energy generating and energy conserving steps as well as between the main possible products (sulfate vs. zero-valent sulfur). Using this framework, we show that the energy conservation efficiency varies widely among SOB with no apparent relationship to their phylogeny. Aerobic SOB equipped with reverse dissimilatory sulfite reductase tend to have higher efficiency than those relying on the complete Sox pathway, whereas for anaerobic SOB the presence of membrane-bound, as opposed to periplasmic, nitrate reductase systems appears to be linked to higher efficiency. We employ the framework to also show how limited rate measurements can be used to estimate the primary productivity of SOB without the knowledge of the sulfate-to-zero-valent-sulfur production ratio. Finally, we discuss how the framework can help researchers gain new insights into the activity of SOB and their niches.
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Affiliation(s)
| | - Lubos Polerecky
- Max Planck Institute for Marine MicrobiologyBremen, Germany
- Department of Earth Sciences – Geochemistry, Faculty of Geosciences, Utrecht UniversityUtrecht, Netherlands
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259
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Zhang Y, Wang L, Hu Y, Xi X, Tang Y, Chen J, Fu X, Sun Y. Water organic pollution and eutrophication influence soil microbial processes, increasing soil respiration of estuarine wetlands: site study in jiuduansha wetland. PLoS One 2015; 10:e0126951. [PMID: 25993326 PMCID: PMC4436345 DOI: 10.1371/journal.pone.0126951] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 04/09/2015] [Indexed: 11/18/2022] Open
Abstract
Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as β-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent.
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Affiliation(s)
- Yue Zhang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
| | - Lei Wang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
- * E-mail:
| | - Yu Hu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
| | - Xuefei Xi
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
| | - Yushu Tang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
| | - Jinhai Chen
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
| | - Xiaohua Fu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai, China
| | - Ying Sun
- Shanghai Jiuduansha wetland Nature Reserve Administration, Shanghai, China
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260
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Abstract
An RNA world has been placed centre stage for explaining the origin of life. Indeed, RNA is the most plausible molecule able to form both a (self)-replicator and to inherit information, necessities for initiating genetics. However, in parallel with self-replication, the proto-organism had to obtain the ability to catalyse supply of its chemical constituents, including the ribonucleotide metabolites required to replicate RNA. Although the possibility of an RNA-catalysed metabolic network has been considered, it is to be questioned whether RNA molecules, at least on their own, possess the required catalytic capacities. An alternative scenario for the origin of metabolism involves chemical reactions that are based on environmental catalysts. Recently, we described a non-enzymatic glycolysis and pentose phosphate pathway-like reactions catalysed by metal ions [mainly Fe(II)] and phosphate, simple inorganic molecules abundantly found in Archaean sediments. While the RNA world can serve to explain the origin of genetics, the origin of the metabolic network might thus date back to constraints of environmental chemistry. Interestingly, considering a metal-catalysed origin of metabolism gives rise to an attractive hypothesis about how the first enzymes could have formed: simple RNA or (poly)peptide molecules could have bound the metal ions, and thus increased their solubility, concentration and accessibility. In a second step, this would have allowed substrate specificity to evolve.
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261
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Heinzelmann SM, Villanueva L, Sinke-Schoen D, Sinninghe Damsté JS, Schouten S, van der Meer MTJ. Impact of metabolism and growth phase on the hydrogen isotopic composition of microbial fatty acids. Front Microbiol 2015; 6:408. [PMID: 26005437 PMCID: PMC4424904 DOI: 10.3389/fmicb.2015.00408] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 04/19/2015] [Indexed: 12/12/2022] Open
Abstract
Microorganisms are involved in all elemental cycles and therefore it is important to study their metabolism in the natural environment. A recent technique to investigate this is the hydrogen isotopic composition of microbial fatty acids, i.e., heterotrophic microorganisms produce fatty acids enriched in deuterium (D) while photoautotrophic and chemoautotrophic microorganisms produce fatty acids depleted in D compared to the water in the culture medium (growth water). However, the impact of factors other than metabolism have not been investigated. Here, we evaluate the impact of growth phase compared to metabolism on the hydrogen isotopic composition of fatty acids of different environmentally relevant microorganisms with heterotrophic, photoautotrophic and chemoautotrophic metabolisms. Fatty acids produced by heterotrophs are enriched in D compared to growth water with εlipid/water between 82 and 359‰ when grown on glucose or acetate, respectively. Photoautotrophs (εlipid/water between −149 and −264‰) and chemoautotrophs (εlipid/water between −217 and −275‰) produce fatty acids depleted in D. Fatty acids become, in general, enriched by between 4 and 46‰ with growth phase which is minor compared to the influence of metabolisms. Therefore, the D/H ratio of fatty acids is a promising tool to investigate community metabolisms in nature.
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Affiliation(s)
- Sandra M Heinzelmann
- Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research Den Burg, Netherlands
| | - Laura Villanueva
- Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research Den Burg, Netherlands
| | - Danielle Sinke-Schoen
- Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research Den Burg, Netherlands
| | - Jaap S Sinninghe Damsté
- Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research Den Burg, Netherlands ; Department of Earth Sciences, Faculty of Geosciences, Utrecht University Utrecht, Netherlands
| | - Stefan Schouten
- Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research Den Burg, Netherlands ; Department of Earth Sciences, Faculty of Geosciences, Utrecht University Utrecht, Netherlands
| | - Marcel T J van der Meer
- Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research Den Burg, Netherlands
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262
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Wang YN, Wang L, Shan YN, Hu J, Tsang Y, Hu Y, Fu X, Le Y. Optimization of inorganic carbon sources to improve the carbon fixation efficiency of the non-photosynthetic microbial community with different electron donors. ENVIRONMENTAL TECHNOLOGY 2015; 36:1246-1255. [PMID: 25367398 DOI: 10.1080/09593330.2014.983991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
As the non-photosynthetic microbial community (NPMC) isolated from seawaters utilized inorganic carbon sources for carbon fixation, the concentrations and ratios of Na2CO3, NaHCO3, and CO2 were optimized by response surface methodology design. With H2 as the electron donor, the optimal carbon sources were 270 mg/L Na2CO3, 580 mg/L NaHCO3, and 120 mg/L CO2. The carbon fixation efficiency in response to total organic carbon (TOC) was up to 30.59 mg/L with optimal carbon sources, which was about 50% higher than that obtained with CO2 as the sole carbon source. The mixture of inorganic carbon sources developed a buffer system to prevent acidification or alkalization of the medium caused by CO2 or Na2CO3, respectively. Furthermore, CO2 and HCO3(-), the starting points of carbon fixation in the pathways of Calvin-Benson-Bassham and 3-hydroxypropionate cycles, were provided by the carbon source structure to facilitate carbon fixation by NPMC. However, in the presence of mixed electron donors composed of 1.25% Na2S, 0.50% Na2S2O3, and 0.457% NaNO2, the carbon source structure did not exhibit significant improvement in the carbon fixation efficiency, when compared with that achieved with CO2 as the sole carbon source. The positive effect of mixed electron donors on inorganic carbon fixation was much higher than that of the carbon source structure. Nevertheless, the carbon source structure could be used as an alternative to CO2 when using NPMC to fix carbon in industrial processes.
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Affiliation(s)
- Ya-nan Wang
- a State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering , Tongji University , Shanghai 200092 , People's Republic of China
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263
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Chi Fru E, Ivarsson M, Kilias SP, Frings PJ, Hemmingsson C, Broman C, Bengtson S, Chatzitheodoridis E. Biogenicity of an Early Quaternary iron formation, Milos Island, Greece. GEOBIOLOGY 2015; 13:225-244. [PMID: 25645266 DOI: 10.1111/gbi.12128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 01/05/2015] [Indexed: 06/04/2023]
Abstract
A ~2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a ~5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk δ(13) C isotopic compositions lower than -25‰ provide evidence for biological contribution by the Calvin and reductive acetyl-CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of ~0.04 wt.% combined with δ(34) S estimates of up to ~18‰ point to a non-sulphidic depository. Positive δ(30) Si records of up to +0.53‰ in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative δ(30) Si data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs.
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Affiliation(s)
- E Chi Fru
- Department of Geological Sciences, Stockholm University, Stockholm, Sweden; Department of Palaeobiology and Nordic Centre for Earth Evolution (NordCEE), Swedish Museum of Natural History, Stockholm, Sweden
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264
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Herrmann M, Rusznyák A, Akob DM, Schulze I, Opitz S, Totsche KU, Küsel K. Large fractions of CO2-fixing microorganisms in pristine limestone aquifers appear to be involved in the oxidation of reduced sulfur and nitrogen compounds. Appl Environ Microbiol 2015; 81:2384-94. [PMID: 25616797 PMCID: PMC4357952 DOI: 10.1128/aem.03269-14] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/17/2015] [Indexed: 11/20/2022] Open
Abstract
The traditional view of the dependency of subsurface environments on surface-derived allochthonous carbon inputs is challenged by increasing evidence for the role of lithoautotrophy in aquifer carbon flow. We linked information on autotrophy (Calvin-Benson-Bassham cycle) with that from total microbial community analysis in groundwater at two superimposed-upper and lower-limestone groundwater reservoirs (aquifers). Quantitative PCR revealed that up to 17% of the microbial population had the genetic potential to fix CO2 via the Calvin cycle, with abundances of cbbM and cbbL genes, encoding RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) forms I and II, ranging from 1.14 × 10(3) to 6 × 10(6) genes liter(-1) over a 2-year period. The structure of the active microbial communities based on 16S rRNA transcripts differed between the two aquifers, with a larger fraction of heterotrophic, facultative anaerobic, soil-related groups in the oxygen-deficient upper aquifer. Most identified CO2-assimilating phylogenetic groups appeared to be involved in the oxidation of sulfur or nitrogen compounds and harbored both RubisCO forms I and II, allowing efficient CO2 fixation in environments with strong oxygen and CO2 fluctuations. The genera Sulfuricella and Nitrosomonas were represented by read fractions of up to 78 and 33%, respectively, within the cbbM and cbbL transcript pool and accounted for 5.6 and 3.8% of 16S rRNA sequence reads, respectively, in the lower aquifer. Our results indicate that a large fraction of bacteria in pristine limestone aquifers has the genetic potential for autotrophic CO2 fixation, with energy most likely provided by the oxidation of reduced sulfur and nitrogen compounds.
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Affiliation(s)
- Martina Herrmann
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Anna Rusznyák
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
| | - Denise M Akob
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany U.S. Geological Survey, Reston, Virginia, USA
| | - Isabel Schulze
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
| | - Sebastian Opitz
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
| | - Kai Uwe Totsche
- Department of Hydrogeology, Institute of Geosciences, Friedrich Schiller University Jena, Jena, Germany
| | - Kirsten Küsel
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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265
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Quantitative PCR analysis of functional genes in iron-rich microbial mats at an active hydrothermal vent system (Lō'ihi Seamount, Hawai'i). Appl Environ Microbiol 2015; 81:2976-84. [PMID: 25681182 DOI: 10.1128/aem.03608-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/09/2015] [Indexed: 01/22/2023] Open
Abstract
The chemolithotrophic Zetaproteobacteria represent a novel class of Proteobacteria which oxidize Fe(II) to Fe(III) and are the dominant bacterial population in iron-rich microbial mats. Zetaproteobacteria were first discovered at Lō'ihi Seamount, located 35 km southeast off the big island of Hawai'i, which is characterized by low-temperature diffuse hydrothermal venting. Novel nondegenerate quantitative PCR (qPCR) assays for genes associated with microbial nitrogen fixation, denitrification, arsenic detoxification, Calvin-Benson-Bassham (CBB), and reductive tricarboxylic acid (rTCA) cycles were developed using selected microbial mat community-derived metagenomes. Nitrogen fixation genes were not detected, but all other functional genes were present. This suggests that arsenic detoxification and denitrification processes are likely cooccurring in addition to two modes of carbon fixation. Two groups of microbial mat community types were identified by terminal restriction fragment length polymorphism (T-RFLP) and were further described based on qPCR data for zetaproteobacterial abundance and carbon fixation mode preference. qPCR variance was associated with mat morphology but not with temperature or sample site. Geochemistry data were significantly associated with sample site and mat morphology. Together, these qPCR assays constitute a functional gene signature for iron microbial mat communities across a broad array of temperatures, mat types, chemistries, and sampling sites at Lō'ihi Seamount.
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266
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Uncertainty of prebiotic scenarios: the case of the non-enzymatic reverse tricarboxylic acid cycle. Sci Rep 2015; 5:8009. [PMID: 25620471 PMCID: PMC4306138 DOI: 10.1038/srep08009] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 12/22/2014] [Indexed: 11/08/2022] Open
Abstract
We consider the hypothesis of the primordial nature of the non-enzymatic reverse tricarboxylic acid (rTCA) cycle and describe a modeling approach to quantify the uncertainty of this hypothesis due to the combinatorial aspect of the constituent chemical transformations. Our results suggest that a) rTCA cycle belongs to a degenerate optimum of auto-catalytic cycles, and b) the set of targets for investigations of the origin of the common metabolic core should be significantly extended.
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267
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Brauer VS, Stomp M, Bouvier T, Fouilland E, Leboulanger C, Confurius-Guns V, Weissing FJ, Stal L, Huisman J. Competition and facilitation between the marine nitrogen-fixing cyanobacterium Cyanothece and its associated bacterial community. Front Microbiol 2015; 5:795. [PMID: 25642224 PMCID: PMC4294207 DOI: 10.3389/fmicb.2014.00795] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 12/23/2014] [Indexed: 11/13/2022] Open
Abstract
N2-fixing cyanobacteria represent a major source of new nitrogen and carbon for marine microbial communities, but little is known about their ecological interactions with associated microbiota. In this study we investigated the interactions between the unicellular N2-fixing cyanobacterium Cyanothece sp. Miami BG043511 and its associated free-living chemotrophic bacteria at different concentrations of nitrate and dissolved organic carbon and different temperatures. High temperature strongly stimulated the growth of Cyanothece, but had less effect on the growth and community composition of the chemotrophic bacteria. Conversely, nitrate and carbon addition did not significantly increase the abundance of Cyanothece, but strongly affected the abundance and species composition of the associated chemotrophic bacteria. In nitrate-free medium the associated bacterial community was co-dominated by the putative diazotroph Mesorhizobium and the putative aerobic anoxygenic phototroph Erythrobacter and after addition of organic carbon also by the Flavobacterium Muricauda. Addition of nitrate shifted the composition toward co-dominance by Erythrobacter and the Gammaproteobacterium Marinobacter. Our results indicate that Cyanothece modified the species composition of its associated bacteria through a combination of competition and facilitation. Furthermore, within the bacterial community, niche differentiation appeared to play an important role, contributing to the coexistence of a variety of different functional groups. An important implication of these findings is that changes in nitrogen and carbon availability due to, e.g., eutrophication and climate change are likely to have a major impact on the species composition of the bacterial community associated with N2-fixing cyanobacteria.
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Affiliation(s)
- Verena S. Brauer
- Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of AmsterdamAmsterdam, Netherlands
- Department of Theoretical Biology, Center for Ecological and Evolutionary Studies, University of GroningenGroningen, Netherlands
- Laboratoire Ecologie des Systèmes Marins Côtiers ECOSYM, UMR 5119, CNRS, IRD, Ifremer, Université Montpellier 2Montpellier, France
| | - Maayke Stomp
- Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of AmsterdamAmsterdam, Netherlands
| | - Thierry Bouvier
- Laboratoire Ecologie des Systèmes Marins Côtiers ECOSYM, UMR 5119, CNRS, IRD, Ifremer, Université Montpellier 2Montpellier, France
| | - Eric Fouilland
- Laboratoire Ecologie des Systèmes Marins Côtiers ECOSYM, UMR 5119, CNRS, IRD, Ifremer, Université Montpellier 2Montpellier, France
| | - Christophe Leboulanger
- Laboratoire Ecologie des Systèmes Marins Côtiers ECOSYM, UMR 5119, CNRS, IRD, Ifremer, Université Montpellier 2Montpellier, France
| | - Veronique Confurius-Guns
- Department of Marine Microbiology, Royal Netherlands Institute for Sea ResearchYerseke, Netherlands
| | - Franz J. Weissing
- Department of Theoretical Biology, Center for Ecological and Evolutionary Studies, University of GroningenGroningen, Netherlands
| | - LucasJ. Stal
- Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of AmsterdamAmsterdam, Netherlands
- Department of Marine Microbiology, Royal Netherlands Institute for Sea ResearchYerseke, Netherlands
| | - Jef Huisman
- Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of AmsterdamAmsterdam, Netherlands
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268
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Glaser R. RuBisCO-Inspired Biomimetic Approaches to Reversible CO 2Capture from Air. ACS SYMPOSIUM SERIES 2015. [DOI: 10.1021/bk-2015-1194.ch011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Rainer Glaser
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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269
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Zwirglmaier K, Reid WDK, Heywood J, Sweeting CJ, Wigham BD, Polunin NVC, Hawkes JA, Connelly DP, Pearce D, Linse K. Linking regional variation of epibiotic bacterial diversity and trophic ecology in a new species of Kiwaidae (Decapoda, Anomura) from East Scotia Ridge (Antarctica) hydrothermal vents. Microbiologyopen 2014; 4:136-50. [PMID: 25515351 PMCID: PMC4335981 DOI: 10.1002/mbo3.227] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 10/16/2014] [Accepted: 10/27/2014] [Indexed: 11/12/2022] Open
Abstract
We analyzed the diversity of bacterial epibionts and trophic ecology of a new species of Kiwa yeti crab discovered at two hydrothermal vent fields (E2 and E9) on the East Scotia Ridge (ESR) in the Southern Ocean using a combination of 454 pyrosequencing, Sanger sequencing, and stable isotope analysis. The Kiwa epibiont communities were dominated by Epsilon- and Gammaproteobacteria. About 454 sequencing of the epibionts on 15 individual Kiwa specimen revealed large regional differences between the two hydrothermal vent fields: at E2, the bacterial community on the Kiwa ventral setae was dominated (up to 75%) by Gammaproteobacteria, whereas at E9 Epsilonproteobacteria dominated (up to 98%). Carbon stable isotope analysis of both Kiwa and the bacterial epibionts also showed distinct differences between E2 and E9 in mean and variability. Both stable isotope and sequence data suggest a dominance of different carbon fixation pathways of the epibiont communities at the two vent fields. At E2, epibionts were putatively fixing carbon via the Calvin-Benson-Bassham and reverse tricarboxylic acid cycle, while at E9 the reverse tricarboxylic acid cycle dominated. Co-varying epibiont diversity and isotope values at E2 and E9 also present further support for the hypothesis that epibionts serve as a food source for Kiwa.
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Affiliation(s)
- Katrin Zwirglmaier
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
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270
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Fei Xi X, Wang L, Jun Hu J, Shu Tang Y, Hu Y, Hua Fu X, Sun Y, Fai Tsang Y, Nan Zhang Y, Hai Chen J. Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community. J Environ Sci (China) 2014; 26:2562-2570. [PMID: 25499505 DOI: 10.1016/j.jes.2014.07.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 07/16/2014] [Accepted: 07/22/2014] [Indexed: 06/04/2023]
Abstract
Estuarine wetland, where freshwater mixes with salt water, comprises different regions (rivers and marine ecosystems) with significantly varying tidal salinities. Two sampling areas, ZXS and JS, were selected to investigate the effect of tidal salinity on soil respiration (SR). ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively, with similar elevation and plant species, but significantly different in salinity. The results showed that with almost identical plant biomass, the SR and soil microbial respiration (SMR) of the tidal wetland with lower salinity (JS) were significantly higher than those of the tidal wetland with higher salinity (ZXS) (p<0.05). However, unlike SMR and SR, the difference in the soil microbial biomass (SMB) was not significant (p>0.05) with the SMB of ZXS a little higher than that of JS. The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria. Abundant β- and γ-Proteobacteria and Actinobacteria in JS soil, which have strong heterotrophic metabolic capabilities, could be the main reason for higher SMR and SR, whereas a high number of ε-Proteobacteria in ZXS, some of which have carbon fixation ability, could be responsible for relatively lower carbon output. Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors, suggesting that higher soil salinity, restricting highly heterotrophic bacteria, is the principle reason for lower SMR and SR in the ZXS.
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Affiliation(s)
- Xue Fei Xi
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China.
| | - Lei Wang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China
| | - Jia Jun Hu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; College of Civil Engineering, Tongji University, Shanghai 200092, China.
| | - Yu Shu Tang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China
| | - Yu Hu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China
| | - Xiao Hua Fu
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China
| | - Ying Sun
- Shanghai Jiuduansha Wetland Nature Reserve Administration, Shanghai 200135, China
| | - Yiu Fai Tsang
- Department of Science and Environmental Studies, Hong Kong Institute of Education, Hong Kong, China
| | - Yan Nan Zhang
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China
| | - Jin Hai Chen
- Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Collaborative Innovation Center for Regional Environmental Quality, China
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271
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The influence of vent systems on pelagic eukaryotic micro-organism composition in the Nordic Seas. Polar Biol 2014. [DOI: 10.1007/s00300-014-1621-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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272
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Marakushev SA, Belonogova OV. Natural selection in coupled autocatalytic modules of carboxylic and phosphoric acids. DOKLADY PHYSICAL CHEMISTRY 2014. [DOI: 10.1134/s0012501614070069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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273
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Beulig F, Heuer VB, Akob DM, Viehweger B, Elvert M, Herrmann M, Hinrichs KU, Küsel K. Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette. ISME JOURNAL 2014; 9:746-59. [PMID: 25216086 DOI: 10.1038/ismej.2014.148] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/02/2014] [Accepted: 07/03/2014] [Indexed: 12/13/2022]
Abstract
Effects of extremely high carbon dioxide (CO2) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO2 degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (ΔpH ∼0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1 Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH4) from hydrogen (H2) and CO2 consistent with elevated CH4 and acetate levels in the mofette soil. (13)CO2 mofette soil incubations showed high label incorporations with ∼512 ng (13)C g (dry weight (dw)) soil(-1) d(-1) into the bulk soil and up to 10.7 ng (13)C g (dw) soil(-1) d(-1) into almost all analyzed bacterial lipids. Incorporation of CO2-derived carbon into archaeal lipids was much lower and restricted to the first 10 cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated with Methanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of (13)CO2. Subdivision 1 Acidobacteriaceae assimilated (13)CO2 likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO2 assimilation. We conclude that CO2-induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.
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Affiliation(s)
- Felix Beulig
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
| | - Verena B Heuer
- Organic Geochemistry Group, Dept. of Geosciences and MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Denise M Akob
- 1] Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany [2] U.S. Geological Survey, Reston, VA, USA
| | - Bernhard Viehweger
- Organic Geochemistry Group, Dept. of Geosciences and MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Marcus Elvert
- Organic Geochemistry Group, Dept. of Geosciences and MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Martina Herrmann
- 1] Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany [2] German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, Germany
| | - Kai-Uwe Hinrichs
- Organic Geochemistry Group, Dept. of Geosciences and MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Kirsten Küsel
- 1] Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany [2] German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, Germany
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274
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Larsen PE, Scott N, Post AF, Field D, Knight R, Hamada Y, Gilbert JA. Satellite remote sensing data can be used to model marine microbial metabolite turnover. ISME JOURNAL 2014; 9:166-79. [PMID: 25072414 PMCID: PMC4274419 DOI: 10.1038/ismej.2014.107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/25/2014] [Accepted: 05/28/2014] [Indexed: 11/09/2022]
Abstract
Sampling ecosystems, even at a local scale, at the temporal and spatial resolution necessary to capture natural variability in microbial communities are prohibitively expensive. We extrapolated marine surface microbial community structure and metabolic potential from 72 16S rRNA amplicon and 8 metagenomic observations using remotely sensed environmental parameters to create a system-scale model of marine microbial metabolism for 5904 grid cells (49 km(2)) in the Western English Chanel, across 3 years of weekly averages. Thirteen environmental variables predicted the relative abundance of 24 bacterial Orders and 1715 unique enzyme-encoding genes that encode turnover of 2893 metabolites. The genes' predicted relative abundance was highly correlated (Pearson Correlation 0.72, P-value <10(-6)) with their observed relative abundance in sequenced metagenomes. Predictions of the relative turnover (synthesis or consumption) of CO2 were significantly correlated with observed surface CO2 fugacity. The spatial and temporal variation in the predicted relative abundances of genes coding for cyanase, carbon monoxide and malate dehydrogenase were investigated along with the predicted inter-annual variation in relative consumption or production of ∼3000 metabolites forming six significant temporal clusters. These spatiotemporal distributions could possibly be explained by the co-occurrence of anaerobic and aerobic metabolisms associated with localized plankton blooms or sediment resuspension, which facilitate the presence of anaerobic micro-niches. This predictive model provides a general framework for focusing future sampling and experimental design to relate biogeochemical turnover to microbial ecology.
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Affiliation(s)
- Peter E Larsen
- Argonne National Laboratory, Biosciences Division, Argonne, IL, USA
| | - Nicole Scott
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
| | - Anton F Post
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Dawn Field
- NERC Centre for Ecology and Hydrology, Wallingford, UK
| | - Rob Knight
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Yuki Hamada
- Argonne National Laboratory, Environmental Science Division, Argonne, IL, USA
| | - Jack A Gilbert
- 1] Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA [2] Argonne National Laboratory, Institute for Genomic and Systems Biology, Argonne, IL, USA
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275
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Urea uptake and carbon fixation by marine pelagic bacteria and archaea during the Arctic summer and winter seasons. Appl Environ Microbiol 2014; 80:6013-22. [PMID: 25063662 DOI: 10.1128/aem.01431-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
How Arctic climate change might translate into alterations of biogeochemical cycles of carbon (C) and nitrogen (N) with respect to inorganic and organic N utilization is not well understood. This study combined 15N uptake rate measurements for ammonium, nitrate, and urea with 15N- and 13C-based DNA stable-isotope probing (SIP). The objective was to identify active bacterial and archeal plankton and their role in N and C uptake during the Arctic summer and winter seasons. We hypothesized that bacteria and archaea would successfully compete for nitrate and urea during the Arctic winter but not during the summer, when phytoplankton dominate the uptake of these nitrogen sources. Samples were collected at a coastal station near Barrow, AK, during August and January. During both seasons, ammonium uptake rates were greater than those for nitrate or urea, and nitrate uptake rates remained lower than those for ammonium or urea. SIP experiments indicated a strong seasonal shift of bacterial and archaeal N utilization from ammonium during the summer to urea during the winter but did not support a similar seasonal pattern of nitrate utilization. Analysis of 16S rRNA gene sequences obtained from each SIP fraction implicated marine group I Crenarchaeota (MGIC) as well as Betaproteobacteria, Firmicutes, SAR11, and SAR324 in N uptake from urea during the winter. Similarly, 13C SIP data suggested dark carbon fixation for MGIC, as well as for several proteobacterial lineages and the Firmicutes. These data are consistent with urea-fueled nitrification by polar archaea and bacteria, which may be advantageous under dark conditions.
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276
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Metaproteomics reveals differential modes of metabolic coupling among ubiquitous oxygen minimum zone microbes. Proc Natl Acad Sci U S A 2014; 111:11395-400. [PMID: 25053816 DOI: 10.1073/pnas.1322132111] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Marine oxygen minimum zones (OMZs) are intrinsic water column features arising from respiratory oxygen demand during organic matter degradation in stratified waters. Currently OMZs are expanding due to global climate change with resulting feedback on marine ecosystem function. Here we use metaproteomics to chart spatial and temporal patterns of gene expression along defined redox gradients in a seasonally stratified fjord to better understand microbial community responses to OMZ expansion. The expression of metabolic pathway components for nitrification, anaerobic ammonium oxidation (anammox), denitrification, and inorganic carbon fixation were differentially expressed across the redoxcline and covaried with distribution patterns of ubiquitous OMZ microbes including Thaumarchaeota, Nitrospina, Nitrospira, Planctomycetes, and SUP05/ARCTIC96BD-19 Gammaproteobacteria. Nitrification and inorganic carbon fixation pathways affiliated with Thaumarchaeota dominated dysoxic waters, and denitrification, sulfur oxidation, and inorganic carbon fixation pathways affiliated with the SUP05 group of nitrate-reducing sulfur oxidizers dominated suboxic and anoxic waters. Nitrifier nitrite oxidation and anammox pathways affiliated with Nirospina, Nitrospira, and Planctomycetes, respectively, also exhibited redox partitioning between dysoxic and suboxic waters. The numerical abundance of SUP05 proteins mediating inorganic carbon fixation under anoxic conditions suggests that SUP05 will become increasingly important in global ocean carbon and nutrient cycling as OMZs expand.
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277
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Reeves EP, Yoshinaga MY, Pjevac P, Goldenstein NI, Peplies J, Meyerdierks A, Amann R, Bach W, Hinrichs KU. Microbial lipids reveal carbon assimilation patterns on hydrothermal sulfide chimneys. Environ Microbiol 2014; 16:3515-32. [DOI: 10.1111/1462-2920.12525] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/25/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Eoghan P. Reeves
- MARUM Center for Marine Environmental Sciences & Department of Geosciences; University of Bremen; Bremen D-28359 Germany
| | - Marcos Y. Yoshinaga
- MARUM Center for Marine Environmental Sciences & Department of Geosciences; University of Bremen; Bremen D-28359 Germany
| | - Petra Pjevac
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen D-28359 Germany
| | - Nadine I. Goldenstein
- MARUM Center for Marine Environmental Sciences & Department of Geosciences; University of Bremen; Bremen D-28359 Germany
| | - Jörg Peplies
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen D-28359 Germany
- Ribocon GmbH; Fahrenheitstrasse 1 Bremen D-28359 Germany
| | - Anke Meyerdierks
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen D-28359 Germany
| | - Rudolf Amann
- Department of Molecular Ecology; Max Planck Institute for Marine Microbiology; Bremen D-28359 Germany
| | - Wolfgang Bach
- MARUM Center for Marine Environmental Sciences & Department of Geosciences; University of Bremen; Bremen D-28359 Germany
| | - Kai-Uwe Hinrichs
- MARUM Center for Marine Environmental Sciences & Department of Geosciences; University of Bremen; Bremen D-28359 Germany
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278
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Thomas F, Giblin AE, Cardon ZG, Sievert SM. Rhizosphere heterogeneity shapes abundance and activity of sulfur-oxidizing bacteria in vegetated salt marsh sediments. Front Microbiol 2014; 5:309. [PMID: 25009538 PMCID: PMC4068000 DOI: 10.3389/fmicb.2014.00309] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/05/2014] [Indexed: 12/02/2022] Open
Abstract
Salt marshes are highly productive ecosystems hosting an intense sulfur (S) cycle, yet little is known about S-oxidizing microorganisms in these ecosystems. Here, we studied the diversity and transcriptional activity of S-oxidizers in salt marsh sediments colonized by the plant Spartina alterniflora, and assessed variations with sediment depth and small-scale compartments within the rhizosphere. We combined next-generation amplicon sequencing of 16S rDNA and rRNA libraries with phylogenetic analyses of marker genes for two S-oxidation pathways (soxB and rdsrAB). Gene and transcript numbers of soxB and rdsrAB phylotypes were quantified simultaneously, using newly designed (RT)-qPCR assays. We identified a diverse assemblage of S-oxidizers, with Chromatiales and Thiotrichales being dominant. The detection of transcripts from S-oxidizers was mostly confined to the upper 5 cm sediments, following the expected distribution of root biomass. A common pool of species dominated by Gammaproteobacteria transcribed S-oxidation genes across roots, rhizosphere, and surrounding sediment compartments, with rdsrAB transcripts prevailing over soxB. However, the root environment fine-tuned the abundance and transcriptional activity of the S-oxidizing community. In particular, the global transcription of soxB was higher on the roots compared to mix and rhizosphere samples. Furthermore, the contribution of Epsilonproteobacteria-related S-oxidizers tended to increase on Spartina roots compared to surrounding sediments. These data shed light on the under-studied oxidative part of the sulfur cycle in salt marsh sediments and indicate small-scale heterogeneities are important factors shaping abundance and potential activity of S-oxidizers in the rhizosphere.
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Affiliation(s)
- François Thomas
- Watson Laboratory, Biology Department, Woods Hole Oceanographic Institution, Woods Hole MA, USA
| | - Anne E Giblin
- Marine Biological Laboratory, The Ecosystems Center, Woods Hole MA, USA
| | - Zoe G Cardon
- Marine Biological Laboratory, The Ecosystems Center, Woods Hole MA, USA
| | - Stefan M Sievert
- Watson Laboratory, Biology Department, Woods Hole Oceanographic Institution, Woods Hole MA, USA
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279
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Pachiadaki MG, Yakimov MM, LaCono V, Leadbetter E, Edgcomb V. Unveiling microbial activities along the halocline of Thetis, a deep-sea hypersaline anoxic basin. ISME JOURNAL 2014; 8:2478-89. [PMID: 24950109 DOI: 10.1038/ismej.2014.100] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/30/2014] [Accepted: 05/11/2014] [Indexed: 11/09/2022]
Abstract
Deep-sea hypersaline anoxic basins (DHABs) in the Eastern Mediterranean Sea are considered some of the most hostile environments on Earth. Little is known about the biochemical adaptations of microorganisms living in these habitats. This first metatranscriptome analysis of DHAB samples provides significant insights into shifts in metabolic activities of microorganisms as physicochemical conditions change from deep Mediterranean sea water to brine. The analysis of Thetis DHAB interface indicates that sulfate reduction occurs in both the upper (7.0-16.3% salinity) and lower (21.4-27.6%) halocline, but that expression of dissimilatory sulfate reductase is reduced in the more hypersaline lower halocline. High dark-carbon assimilation rates in the upper interface coincided with high abundance of transcripts for ribulose 1,5-bisphosphate carboxylase affiliated to sulfur-oxidizing bacteria. In the lower interface, increased expression of genes associated with methane metabolism and osmoregulation is noted. In addition, in this layer, nitrogenase transcripts affiliated to uncultivated putative methanotrophic archaea were detected, implying nitrogen fixation in this anoxic habitat, and providing evidence of linked carbon, nitrogen and sulfur cycles.
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Affiliation(s)
| | | | - Violetta LaCono
- CNR-Institute for Coastal Marine Environment, Messina, Italy
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280
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Genomic insights into the uncultured genus 'Candidatus Magnetobacterium' in the phylum Nitrospirae. ISME JOURNAL 2014; 8:2463-77. [PMID: 24914800 DOI: 10.1038/ismej.2014.94] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 04/27/2014] [Accepted: 05/08/2014] [Indexed: 11/09/2022]
Abstract
Magnetotactic bacteria (MTB) of the genus 'Candidatus Magnetobacterium' in phylum Nitrospirae are of great interest because of the formation of hundreds of bullet-shaped magnetite magnetosomes in multiple bundles of chains per cell. These bacteria are worldwide distributed in aquatic environments and have important roles in the biogeochemical cycles of iron and sulfur. However, except for a few short genomic fragments, no genome data are available for this ecologically important genus, and little is known about their metabolic capacity owing to the lack of pure cultures. Here we report the first draft genome sequence of 3.42 Mb from an uncultivated strain tentatively named 'Ca. Magnetobacterium casensis' isolated from Lake Miyun, China. The genome sequence indicates an autotrophic lifestyle using the Wood-Ljungdahl pathway for CO2 fixation, which has not been described in any previously known MTB or Nitrospirae organisms. Pathways involved in the denitrification, sulfur oxidation and sulfate reduction have been predicted, indicating its considerable capacity for adaptation to variable geochemical conditions and roles in local biogeochemical cycles. Moreover, we have identified a complete magnetosome gene island containing mam, mad and a set of novel genes (named as man genes) putatively responsible for the formation of bullet-shaped magnetite magnetosomes and the arrangement of multiple magnetosome chains. This first comprehensive genomic analysis sheds light on the physiology, ecology and biomineralization of the poorly understood 'Ca. Magnetobacterium' genus.
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281
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Ammonia-oxidizing archaea use the most energy-efficient aerobic pathway for CO2 fixation. Proc Natl Acad Sci U S A 2014; 111:8239-44. [PMID: 24843170 DOI: 10.1073/pnas.1402028111] [Citation(s) in RCA: 241] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Archaea of the phylum Thaumarchaeota are among the most abundant prokaryotes on Earth and are widely distributed in marine, terrestrial, and geothermal environments. All studied Thaumarchaeota couple the oxidation of ammonia at extremely low concentrations with carbon fixation. As the predominant nitrifiers in the ocean and in various soils, ammonia-oxidizing archaea contribute significantly to the global nitrogen and carbon cycles. Here we provide biochemical evidence that thaumarchaeal ammonia oxidizers assimilate inorganic carbon via a modified version of the autotrophic hydroxypropionate/hydroxybutyrate cycle of Crenarchaeota that is far more energy efficient than any other aerobic autotrophic pathway. The identified genes of this cycle were found in the genomes of all sequenced representatives of the phylum Thaumarchaeota, indicating the environmental significance of this efficient CO2-fixation pathway. Comparative phylogenetic analysis of proteins of this pathway suggests that the hydroxypropionate/hydroxybutyrate cycle emerged independently in Crenarchaeota and Thaumarchaeota, thus supporting the hypothesis of an early evolutionary separation of both archaeal phyla. We conclude that high efficiency of anabolism exemplified by this autotrophic cycle perfectly suits the lifestyle of ammonia-oxidizing archaea, which thrive at a constantly low energy supply, thus offering a biochemical explanation for their ecological success in nutrient-limited environments.
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282
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Diaz MR, Van Norstrand JD, Eberli GP, Piggot AM, Zhou J, Klaus JS. Functional gene diversity of oolitic sands from Great Bahama Bank. GEOBIOLOGY 2014; 12:231-249. [PMID: 24612324 DOI: 10.1111/gbi.12079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 01/22/2014] [Indexed: 06/03/2023]
Abstract
Despite the importance of oolitic depositional systems as indicators of climate and reservoirs of inorganic C, little is known about the microbial functional diversity, structure, composition, and potential metabolic processes leading to precipitation of carbonates. To fill this gap, we assess the metabolic gene carriage and extracellular polymeric substance (EPS) development in microbial communities associated with oolitic carbonate sediments from the Bahamas Archipelago. Oolitic sediments ranging from high-energy 'active' to lower energy 'non-active' and 'microbially stabilized' environments were examined as they represent contrasting depositional settings, mostly influenced by tidal flows and wave-generated currents. Functional gene analysis, which employed a microarray-based gene technology, detected a total of 12,432 of 95,847 distinct gene probes, including a large number of metabolic processes previously linked to mineral precipitation. Among these, gene-encoding enzymes for denitrification, sulfate reduction, ammonification, and oxygenic/anoxygenic photosynthesis were abundant. In addition, a broad diversity of genes was related to organic carbon degradation, and N2 fixation implying these communities has metabolic plasticity that enables survival under oligotrophic conditions. Differences in functional genes were detected among the environments, with higher diversity associated with non-active and microbially stabilized environments in comparison with the active environment. EPS showed a gradient increase from active to microbially stabilized communities, and when combined with functional gene analysis, which revealed genes encoding EPS-degrading enzymes (chitinases, glucoamylase, amylases), supports a putative role of EPS-mediated microbial calcium carbonate precipitation. We propose that carbonate precipitation in marine oolitic biofilms is spatially and temporally controlled by a complex consortium of microbes with diverse physiologies, including photosynthesizers, heterotrophs, denitrifiers, sulfate reducers, and ammonifiers.
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Affiliation(s)
- M R Diaz
- Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
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283
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Keller MA, Turchyn AV, Ralser M. Non-enzymatic glycolysis and pentose phosphate pathway-like reactions in a plausible Archean ocean. Mol Syst Biol 2014; 10:725. [PMID: 24771084 PMCID: PMC4023395 DOI: 10.1002/msb.20145228] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 03/11/2014] [Accepted: 03/18/2014] [Indexed: 11/30/2022] Open
Abstract
The reaction sequences of central metabolism, glycolysis and the pentose phosphate pathway provide essential precursors for nucleic acids, amino acids and lipids. However, their evolutionary origins are not yet understood. Here, we provide evidence that their structure could have been fundamentally shaped by the general chemical environments in earth's earliest oceans. We reconstructed potential scenarios for oceans of the prebiotic Archean based on the composition of early sediments. We report that the resultant reaction milieu catalyses the interconversion of metabolites that in modern organisms constitute glycolysis and the pentose phosphate pathway. The 29 observed reactions include the formation and/or interconversion of glucose, pyruvate, the nucleic acid precursor ribose-5-phosphate and the amino acid precursor erythrose-4-phosphate, antedating reactions sequences similar to that used by the metabolic pathways. Moreover, the Archean ocean mimetic increased the stability of the phosphorylated intermediates and accelerated the rate of intermediate reactions and pyruvate production. The catalytic capacity of the reconstructed ocean milieu was attributable to its metal content. The reactions were particularly sensitive to ferrous iron Fe(II), which is understood to have had high concentrations in the Archean oceans. These observations reveal that reaction sequences that constitute central carbon metabolism could have been constrained by the iron-rich oceanic environment of the early Archean. The origin of metabolism could thus date back to the prebiotic world.
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Affiliation(s)
- Markus A Keller
- Department of Biochemistry and Cambridge Systems Biology CentreUniversity of CambridgeCambridgeUK
| | | | - Markus Ralser
- Department of Biochemistry and Cambridge Systems Biology CentreUniversity of CambridgeCambridgeUK
- Division of Physiology and MetabolismMRC National Institute for Medical ResearchMill HillLondonUK
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284
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Abstract
Magnetotactic bacteria (MTB) are widespread, motile, diverse prokaryotes that biomineralize a unique organelle called the magnetosome. Magnetosomes consist of a nano-sized crystal of a magnetic iron mineral that is enveloped by a lipid bilayer membrane. In cells of almost all MTB, magnetosomes are organized as a well-ordered chain. The magnetosome chain causes the cell to behave like a motile, miniature compass needle where the cell aligns and swims parallel to magnetic field lines. MTB are found in almost all types of aquatic environments, where they can account for an important part of the bacterial biomass. The genes responsible for magnetosome biomineralization are organized as clusters in the genomes of MTB, in some as a magnetosome genomic island. The functions of a number of magnetosome genes and their associated proteins in magnetosome synthesis and construction of the magnetosome chain have now been elucidated. The origin of magnetotaxis appears to be monophyletic; that is, it developed in a common ancestor to all MTB, although horizontal gene transfer of magnetosome genes also appears to play a role in their distribution. The purpose of this review, based on recent progress in this field, is focused on the diversity and the ecology of the MTB and also the evolution and transfer of the molecular determinants involved in magnetosome formation.
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285
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Fuchs G, Berg IA. Unfamiliar metabolic links in the central carbon metabolism. J Biotechnol 2014; 192 Pt B:314-22. [PMID: 24576434 DOI: 10.1016/j.jbiotec.2014.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/13/2014] [Accepted: 02/17/2014] [Indexed: 11/18/2022]
Abstract
The central carbon metabolism of all organisms is considered to follow a well established fixed scheme. However, recent studies of autotrophic carbon fixation in prokaryotes revealed unfamiliar metabolic links. A new route interconnects acetyl-coenzyme A (CoA) via 3-hydroxypropionate with succinyl-CoA. Succinyl-CoA in turn may be metabolized via 4-hydroxybutyrate to two molecules of acetyl-CoA; a reversal of this route would result in the assimilation of two molecules of acetyl-CoA into C4 compounds. C5-dicarboxylic acids are a rather neglected class of metabolites; yet, they play a key role not only in one of the CO2 fixation cycles, but also in two acetate assimilation pathways that replace the glyoxylate cycle. C5 compounds such as ethylmalonate, methylsuccinate, methylmalate, mesaconate, itaconate and citramalate or their CoA esters are thereby linked to the acetyl-CoA, propionyl-CoA, glyoxylate and pyruvate pools. A novel carboxylase/reductase converts crotonyl-CoA into ethylmalonyl-CoA; similar reductive carboxylations apply to other alpha-beta-unsaturated carboxy-CoA thioesters. These unfamiliar metabolic links may provide useful tools for metabolic engineering.
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Affiliation(s)
- Georg Fuchs
- Mikrobiologie, Fakultät für Biologie, Universität Freiburg, Schänzlestr. 1, D 79104 Freiburg, Germany.
| | - Ivan A Berg
- Mikrobiologie, Fakultät für Biologie, Universität Freiburg, Schänzlestr. 1, D 79104 Freiburg, Germany.
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286
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Braakman R, Smith E. Metabolic evolution of a deep-branching hyperthermophilic chemoautotrophic bacterium. PLoS One 2014; 9:e87950. [PMID: 24516572 PMCID: PMC3917532 DOI: 10.1371/journal.pone.0087950] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 01/05/2014] [Indexed: 11/19/2022] Open
Abstract
Aquifex aeolicus is a deep-branching hyperthermophilic chemoautotrophic bacterium restricted to hydrothermal vents and hot springs. These characteristics make it an excellent model system for studying the early evolution of metabolism. Here we present the whole-genome metabolic network of this organism and examine in detail the driving forces that have shaped it. We make extensive use of phylometabolic analysis, a method we recently introduced that generates trees of metabolic phenotypes by integrating phylogenetic and metabolic constraints. We reconstruct the evolution of a range of metabolic sub-systems, including the reductive citric acid (rTCA) cycle, as well as the biosynthesis and functional roles of several amino acids and cofactors. We show that A. aeolicus uses the reconstructed ancestral pathways within many of these sub-systems, and highlight how the evolutionary interconnections between sub-systems facilitated several key innovations. Our analyses further highlight three general classes of driving forces in metabolic evolution. One is the duplication and divergence of genes for enzymes as these progress from lower to higher substrate specificity, improving the kinetics of certain sub-systems. A second is the kinetic optimization of established pathways through fusion of enzymes, or their organization into larger complexes. The third is the minimization of the ATP unit cost to synthesize biomass, improving thermodynamic efficiency. Quantifying the distribution of these classes of innovations across metabolic sub-systems and across the tree of life will allow us to assess how a tradeoff between maximizing growth rate and growth efficiency has shaped the long-term metabolic evolution of the biosphere.
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Affiliation(s)
- Rogier Braakman
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
- * E-mail:
| | - Eric Smith
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
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287
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Abstract
Sulfur is an important element in sustaining microbial communities present in hydrothermal vents. Sulfur oxidation has been extensively studied due to its importance in chemosynthetic pathways in hydrothermal fields; however, less is known about sulfate reduction. Here, the metagenomes of hydrothermal chimneys located on the ultraslow-spreading Southwest Indian Ridge (SWIR) were pyrosequenced to elucidate the associated microbial sulfur cycle. A taxonomic summary of known genes revealed a few dominant bacteria that participated in the microbial sulfur cycle, particularly sulfate-reducing Deltaproteobacteria. The metagenomes studied contained highly abundant genes related to sulfur oxidation and reduction. Several carbon metabolic pathways, in particular the Calvin-Benson-Bassham pathway and the reductive tricarboxylic acid cycles for CO2 fixation, were identified in sulfur-oxidizing autotrophic bacteria. In contrast, highly abundant genes related to the oxidation of short-chain alkanes were grouped with sulfate-reducing bacteria, suggesting an important role for short-chain alkanes in the sulfur cycle. Furthermore, sulfur-oxidizing bacteria were associated with enrichment for genes involved in the denitrification pathway, while sulfate-reducing bacteria displayed enrichment for genes responsible for hydrogen utilization. In conclusion, this study provides insights regarding major microbial metabolic activities that are driven by the sulfur cycle in low-temperature hydrothermal chimneys present on an ultraslow midocean ridge. There have been limited studies on chimney sulfides located at ultraslow-spreading ridges. The analysis of metagenomes of hydrothermal chimneys on the ultraslow-spreading Southwest Indian Ridge suggests the presence of a microbial sulfur cycle. The sulfur cycle should be centralized within a microbial community that displays enrichment for sulfur metabolism-related genes. The present study elucidated a significant role of the microbial sulfur cycle in sustaining an entire microbial community in low-temperature hydrothermal chimneys on an ultraslow spreading midocean ridge, which has characteristics distinct from those of other types of hydrothermal fields.
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288
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Li ZY, Wang YZ, He LM, Zheng HJ. Metabolic profiles of prokaryotic and eukaryotic communities in deep-sea sponge Neamphius huxleyi [corrected]. indicated by metagenomics. Sci Rep 2014; 4:3895. [PMID: 24463735 PMCID: PMC5379212 DOI: 10.1038/srep03895] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 01/08/2014] [Indexed: 01/29/2023] Open
Abstract
The whole metabolism of a sponge holobiont and the respective contributions of prokaryotic and eukaryotic symbionts and their associations with the sponge host remain largely unclear. Meanwhile, compared with shallow water sponges, deep-sea sponges are rarely understood. Here we report the metagenomic exploration of deep-sea sponge Neamphius huxleyi at the whole community level. Metagenomic data showed phylogenetically diverse prokaryotes and eukaryotes in Neamphius huxleyi. MEGAN and gene enrichment analyses indicated different metabolic potentials of prokaryotic symbionts from eukaryotic symbionts, especially in nitrogen and carbon metabolisms, and their molecular interactions with the sponge host. These results supported the hypothesis that prokaryotic and eukaryotic symbionts have different ecological roles and relationships with sponge host. Moreover, vigorous denitrification, and CO2 fixation by chemoautotrophic prokaryotes were suggested for this deep-sea sponge. The study provided novel insights into the respective potentials of prokaryotic and eukaryotic symbionts and their associations with deep-sea sponge Neamphius huxleyi.
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Affiliation(s)
- Zhi-Yong Li
- Marine Biotechnology Laboratory, State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Yue-Zhu Wang
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, P. R. China
| | - Li-Ming He
- Marine Biotechnology Laboratory, State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Hua-Jun Zheng
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, P. R. China
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289
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Energy Conservation in Heliobacteria: Photosynthesis and Central Carbon Metabolism. THE STRUCTURAL BASIS OF BIOLOGICAL ENERGY GENERATION 2014. [DOI: 10.1007/978-94-017-8742-0_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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290
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Herndl GJ, Reinthaler T. Microbial control of the dark end of the biological pump. NATURE GEOSCIENCE 2013; 6:718-724. [PMID: 24707320 PMCID: PMC3972885 DOI: 10.1038/ngeo1921] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A fraction of the carbon captured by phytoplankton in the sunlit surface ocean sinks to depth as dead organic matter and faecal material. The microbial breakdown of this material in the subsurface ocean generates carbon dioxide. Collectively, this microbially mediated flux of carbon from the atmosphere to the ocean interior is termed the biological pump. In recent decades it has become clear that the composition of the phytoplankton community in the surface ocean largely determines the quantity and quality of organic matter that sinks to depth. This settling organic matter, however, is not sufficient to meet the energy demands of microbes in the dark ocean. Two additional sources of organic matter have been identified: non-sinking organic particles of debated origin that escape capture by sediment traps and exhibit stable concentrations throughout the dark ocean, and microbes that convert inorganic carbon into organic matter. Whether these two sources can together account for the significant mismatch between organic matter consumption and supply in the dark ocean remains to be seen. It is clear, however, that the microbial community of the deep ocean works in a fundamentally different way from surface water communities.
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Affiliation(s)
- Gerhard J. Herndl
- Department of Limnology and Oceanography, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
- Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, 1790 AB Den Burg, Texel, The Netherlands
- Correspondence and requests for materials should be addressed to G.J.H.
| | - Thomas Reinthaler
- Department of Limnology and Oceanography, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
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291
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Functional metagenomic investigations of microbial communities in a shallow-sea hydrothermal system. PLoS One 2013; 8:e72958. [PMID: 23940820 PMCID: PMC3735525 DOI: 10.1371/journal.pone.0072958] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 07/22/2013] [Indexed: 12/20/2022] Open
Abstract
Little is known about the functional capability of microbial communities in shallow-sea hydrothermal systems (water depth of <200 m). This study analyzed two high-throughput pyrosequencing metagenomic datasets from the vent and the surface water in the shallow-sea hydrothermal system offshore NE Taiwan. This system exhibited distinct geochemical parameters. Metagenomic data revealed that the vent and the surface water were predominated by Epsilonproteobacteria (Nautiliales-like organisms) and Gammaproteobacteria (Thiomicrospira-like organisms), respectively. A significant difference in microbial carbon fixation and sulfur metabolism was found between the vent and the surface water. The chemoautotrophic microorganisms in the vent and in the surface water might possess the reverse tricarboxylic acid cycle and the Calvin-Bassham-Benson cycle for carbon fixation in response to carbon dioxide highly enriched in the environment, which is possibly fueled by geochemical energy with sulfur and hydrogen. Comparative analyses of metagenomes showed that the shallow-sea metagenomes contained some genes similar to those present in other extreme environments. This study may serve as a basis for deeply understanding the genetic network and functional capability of the microbial members of shallow-sea hydrothermal systems.
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292
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Ji B, Zhang SD, Arnoux P, Rouy Z, Alberto F, Philippe N, Murat D, Zhang WJ, Rioux JB, Ginet N, Sabaty M, Mangenot S, Pradel N, Tian J, Yang J, Zhang L, Zhang W, Pan H, Henrissat B, Coutinho PM, Li Y, Xiao T, Médigue C, Barbe V, Pignol D, Talla E, Wu LF. Comparative genomic analysis provides insights into the evolution and niche adaptation of marine Magnetospira sp. QH-2 strain. Environ Microbiol 2013; 16:525-44. [PMID: 23841906 DOI: 10.1111/1462-2920.12180] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/17/2013] [Accepted: 06/02/2013] [Indexed: 11/30/2022]
Abstract
Magnetotactic bacteria (MTB) are capable of synthesizing intracellular organelles, the magnetosomes, that are membrane-bounded magnetite or greigite crystals arranged in chains. Although MTB are widely spread in various ecosystems, few axenic cultures are available, and only freshwater Magnetospirillum spp. have been genetically analysed. Here, we present the complete genome sequence of a marine magnetotactic spirillum, Magnetospira sp. QH-2. The high number of repeats and transposable elements account for the differences in QH-2 genome structure compared with other relatives. Gene cluster synteny and gene correlation analyses indicate that the insertion of the magnetosome island in the QH-2 genome occurred after divergence between freshwater and marine magnetospirilla. The presence of a sodium-quinone reductase, sodium transporters and other functional genes are evidence of the adaptive evolution of Magnetospira sp. QH-2 to the marine ecosystem. Genes well conserved among freshwater magnetospirilla for nitrogen fixation and assimilatory nitrate respiration are absent from the QH-2 genome. Unlike freshwater Magnetospirillum spp., marine Magnetospira sp. QH-2 neither has TonB and TonB-dependent receptors nor does it grow on trace amounts of iron. Taken together, our results show a distinct, adaptive evolution of Magnetospira sp. QH-2 to marine sediments in comparison with its closely related freshwater counterparts.
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Affiliation(s)
- Boyang Ji
- Laboratoire de Chimie Bactérienne, Aix-Marseille Université, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7283, F-13402, Marseille Cedex 20, France
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293
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Sheik CS, Jain S, Dick GJ. Metabolic flexibility of enigmatic SAR324 revealed through metagenomics and metatranscriptomics. Environ Microbiol 2013; 16:304-17. [PMID: 23809230 DOI: 10.1111/1462-2920.12165] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 05/09/2013] [Accepted: 05/24/2013] [Indexed: 11/27/2022]
Abstract
Chemolithotrophy is a pervasive metabolic lifestyle for microorganisms in the dark ocean. The SAR324 group of Deltaproteobacteria is ubiquitous in the ocean and has been implicated in sulfur oxidation and carbon fixation, but also contains genomic signatures of C1 utilization and heterotrophy. Here, we reconstructed the metagenome and metatranscriptome of a population of SAR324 from a hydrothermal plume and surrounding waters in the deep Gulf of California to gain insight into the genetic capability and transcriptional dynamics of this enigmatic group. SAR324's metabolism is signified by genes that encode a novel particulate hydrocarbon monooxygenase (pHMO), degradation pathways for corresponding alcohols and short-chain fatty acids, dissimilatory sulfur oxidation, formate dehydrogenase (FDH) and a nitrite reductase (NirK). Transcripts of the pHMO, NirK, FDH and transporters for exogenous carbon and amino acid uptake were highly abundant in plume waters. Sulfur oxidation genes were also abundant in the plume metatranscriptome, indicating SAR324 may also utilize reduced sulfur species in hydrothermal fluids. These results suggest that aspects of SAR324's versatile metabolism (lithotrophy, heterotrophy and alkane oxidation) operate simultaneously, and may explain SAR324's ubiquity in the deep Gulf of California and in the global marine biosphere.
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Affiliation(s)
- Cody S Sheik
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109, USA
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294
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Reid WDK, Sweeting CJ, Wigham BD, Zwirglmaier K, Hawkes JA, McGill RAR, Linse K, Polunin NVC. Spatial differences in East scotia ridge hydrothermal vent food webs: influences of chemistry, microbiology and predation on trophodynamics. PLoS One 2013; 8:e65553. [PMID: 23762393 PMCID: PMC3676328 DOI: 10.1371/journal.pone.0065553] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/25/2013] [Indexed: 11/30/2022] Open
Abstract
The hydrothermal vents on the East Scotia Ridge are the first to be explored in the Antarctic and are dominated by large peltospiroid gastropods, stalked barnacles (Vulcanolepas sp.) and anomuran crabs (Kiwa sp.) but their food webs are unknown. Vent fluid and macroconsumer samples were collected at three vent sites (E2, E9N and E9S) at distances of tens of metres to hundreds of kilometres apart with contrasting vent fluid chemistries to describe trophic interactions and identify potential carbon fixation pathways using stable isotopes. δ(13)C of dissolved inorganic carbon from vent fluids ranged from -4.6‰ to 0.8‰ at E2 and from -4.4‰ to 1.5‰ at E9. The lowest macroconsumer δ(13)C was observed in peltospiroid gastropods (-30.0‰ to -31.1‰) and indicated carbon fixation via the Calvin-Benson-Bassham (CBB) cycle by endosymbiotic gamma-Proteobacteria. Highest δ(13)C occurred in Kiwa sp. (-19.0‰ to -10.5‰), similar to that of the epibionts sampled from their ventral setae. Kiwa sp. δ(13)C differed among sites, which were attributed to spatial differences in the epibiont community and the relative contribution of carbon fixed via the reductive tricarboxylic acid (rTCA) and CBB cycles assimilated by Kiwa sp. Site differences in carbon fixation pathways were traced into higher trophic levels e.g. a stichasterid asteroid that predates on Kiwa sp. Sponges and anemones at the periphery of E2 assimilated a proportion of epipelagic photosynthetic primary production but this was not observed at E9N. Differences in the δ(13)C and δ(34)S values of vent macroconsumers between E2 and E9 sites suggest the relative contributions of photosynthetic and chemoautotrophic carbon fixation (rTCA v CBB) entering the hydrothermal vent food webs vary between the sites.
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Affiliation(s)
- William D K Reid
- School of Marine Science and Technology, Newcastle University, Newcastle upon Tyne, United Kingdom.
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295
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Marakushev SA, Belonogova OV. The divergence and natural selection of autocatalytic primordial metabolic systems. ORIGINS LIFE EVOL B 2013; 43:263-81. [PMID: 23860777 DOI: 10.1007/s11084-013-9340-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/28/2013] [Indexed: 11/24/2022]
Abstract
The diversity of the central metabolism of modern organisms is caused by the existence of a few metabolic modules, combination of which produces multiple metabolic pathways. This paper analyzes biomimetically reconstructed coupled autocatalytic cycles as the basis of ancestral metabolic systems. The mechanism for natural selection and evolution in autocatalytic chemical systems may be affected by natural homeostatic parameters such as ambient chemical potentials, temperature, and pressure. Competition between separate parts of an autocatalytic network with positive-plus-negative feedback resulted in the formation of primordial autotrophic, mixotrophic, and heterotrophic metabolic systems. This work examined the last common ancestor of a set of coupled metabolic cycles in a population of protocells. Physical-chemical properties of these cycles determined the main principles of natural selection for the ancestral Bacteria and Archaea taxa.
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Affiliation(s)
- Sergey A Marakushev
- Institute of Problem of Chemical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia.
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296
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Grostern A, Alvarez-Cohen L. RubisCO-based CO2 fixation and C1 metabolism in the actinobacterium Pseudonocardia dioxanivorans CB1190. Environ Microbiol 2013; 15:3040-53. [PMID: 23663433 DOI: 10.1111/1462-2920.12144] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 04/12/2013] [Indexed: 01/01/2023]
Abstract
Pseudonocardia is an actinobacterial genus of interest due to its potential biotechnological, medical and environmental remediation applications, as well as for the ecologically relevant symbiotic relationships it forms with attine ants. Some Pseudonocardia spp. can grow autotrophically, but the genetic basis of this capability has not previously been reported. In this study, we examined autotrophy in Pseudonocardia dioxanivorans CB1190, which can grow using H2 and CO2, as well as heterotrophically. Genomic and transcriptomic analysis of CB1190 cells grown with H2/bicarbonate implicated the Calvin-Benson-Bassham (CBB) cycle in growth-supporting CO2 fixation, as well as a [NiFe] hydrogenase-encoding gene cluster in H2 oxidation. The CBB cycle genes are evolutionarily most related to actinobacterial homologues, although synteny has not been maintained. Ribulose-1,5-bisphosphate carboxylase activity was confirmed in H2/bicarbonate-grown CB1190 cells and was detected in cells grown with the C1 compounds formate, methanol and carbon monoxide. We also demonstrated the upregulation of CBB cycle genes upon exposure of CB1190 to these C1 substrates, and identified genes putatively involved in generating CO2 from the C1 substrates by using RT-qPCR. Finally, the potential for autotrophic growth of other Pseudonocardia spp. was explored, and the ecological implications of autotrophy in attine ant- and plant root-associated Pseudonocardia discussed.
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Affiliation(s)
- Ariel Grostern
- Department of Civil and Environmental Engineering, UC Berkeley, Berkeley, CA, USA.
| | - Lisa Alvarez-Cohen
- Department of Civil and Environmental Engineering, UC Berkeley, Berkeley, CA, USA.,Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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297
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Olins HC, Rogers DR, Frank KL, Vidoudez C, Girguis PR. Assessing the influence of physical, geochemical and biological factors on anaerobic microbial primary productivity within hydrothermal vent chimneys. GEOBIOLOGY 2013; 11:279-293. [PMID: 23551687 DOI: 10.1111/gbi.12034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 02/25/2013] [Indexed: 06/02/2023]
Abstract
Chemosynthetic primary production supports hydrothermal vent ecosystems, but the extent of that productivity and its governing factors have not been well constrained. To better understand anaerobic primary production within massive vent deposits, we conducted a series of incubations at 4, 25, 50 and 90 °C using aggregates recovered from hydrothermal vent structures. We documented in situ geochemistry, measured autochthonous organic carbon stable isotope ratios and assessed microbial community composition and functional gene abundances in three hydrothermal vent chimney structures from Middle Valley on the Juan de Fuca Ridge. Carbon fixation rates were greatest at lower temperatures and were comparable among chimneys. Stable isotope ratios of autochthonous organic carbon were consistent with the Calvin-Benson-Bassham cycle being the predominant mode of carbon fixation for all three chimneys. Chimneys exhibited marked differences in vent fluid geochemistry and microbial community composition, with structures being differentially dominated by gamma (γ) or epsilon (ε) proteobacteria. Similarly, qPCR analyses of functional genes representing different carbon fixation pathways showed striking differences in gene abundance among chimney structures. Carbon fixation rates showed no obvious correlation with observed in situ vent fluid geochemistry, community composition or functional gene abundance. Together, these data reveal that (i) net anaerobic carbon fixation rates among these chimneys are elevated at lower temperatures, (ii) clear differences in community composition and gene abundance exist among chimney structures, and (iii) tremendous spatial heterogeneity within these environments likely confounds efforts to relate the observed rates to in situ microbial and geochemical factors. We also posit that microbes typically thought to be mesophiles are likely active and growing at cooler temperatures, and that their activity at these temperatures comprises the majority of endolithic anaerobic primary production in hydrothermal vent chimneys.
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Affiliation(s)
- H C Olins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
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298
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Yau S, Lauro FM, Williams TJ, Demaere MZ, Brown MV, Rich J, Gibson JA, Cavicchioli R. Metagenomic insights into strategies of carbon conservation and unusual sulfur biogeochemistry in a hypersaline Antarctic lake. ISME JOURNAL 2013; 7:1944-61. [PMID: 23619305 DOI: 10.1038/ismej.2013.69] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/20/2013] [Accepted: 03/24/2013] [Indexed: 01/14/2023]
Abstract
Organic Lake is a shallow, marine-derived hypersaline lake in the Vestfold Hills, Antarctica that has the highest reported concentration of dimethylsulfide (DMS) in a natural body of water. To determine the composition and functional potential of the microbial community and learn about the unusual sulfur chemistry in Organic Lake, shotgun metagenomics was performed on size-fractionated samples collected along a depth profile. Eucaryal phytoflagellates were the main photosynthetic organisms. Bacteria were dominated by the globally distributed heterotrophic taxa Marinobacter, Roseovarius and Psychroflexus. The dominance of heterotrophic degradation, coupled with low fixation potential, indicates possible net carbon loss. However, abundant marker genes for aerobic anoxygenic phototrophy, sulfur oxidation, rhodopsins and CO oxidation were also linked to the dominant heterotrophic bacteria, and indicate the use of photo- and lithoheterotrophy as mechanisms for conserving organic carbon. Similarly, a high genetic potential for the recycling of nitrogen compounds likely functions to retain fixed nitrogen in the lake. Dimethylsulfoniopropionate (DMSP) lyase genes were abundant, indicating that DMSP is a significant carbon and energy source. Unlike marine environments, DMSP demethylases were less abundant, indicating that DMSP cleavage is the likely source of high DMS concentration. DMSP cleavage, carbon mixotrophy (photoheterotrophy and lithoheterotrophy) and nitrogen remineralization by dominant Organic Lake bacteria are potentially important adaptations to nutrient constraints. In particular, carbon mixotrophy relieves the extent of carbon oxidation for energy production, allowing more carbon to be used for biosynthetic processes. The study sheds light on how the microbial community has adapted to this unique Antarctic lake environment.
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Affiliation(s)
- Sheree Yau
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia
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299
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Hawkins AS, McTernan PM, Lian H, Kelly RM, Adams MWW. Biological conversion of carbon dioxide and hydrogen into liquid fuels and industrial chemicals. Curr Opin Biotechnol 2013; 24:376-84. [PMID: 23510698 DOI: 10.1016/j.copbio.2013.02.017] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/18/2013] [Accepted: 02/19/2013] [Indexed: 12/12/2022]
Abstract
Non-photosynthetic routes for biological fixation of carbon dioxide into valuable industrial chemical precursors and fuels are moving from concept to reality. The development of 'electrofuel'-producing microorganisms leverages techniques in synthetic biology, genetic and metabolic engineering, as well as systems-level multi-omic analysis, directed evolution, and in silico modeling. Electrofuel processes are being developed for a range of microorganisms and energy sources (e.g. hydrogen, formate, electricity) to produce a variety of target molecules (e.g. alcohols, terpenes, alkenes). This review examines the current landscape of electrofuel projects with a focus on hydrogen-utilizing organisms covering the biochemistry of hydrogenases and carbonic anhydrases, kinetic and energetic analyses of the known carbon fixation pathways, and the state of genetic systems for current and prospective electrofuel-producing microorganisms.
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Affiliation(s)
- Aaron S Hawkins
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, United States
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300
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Balsera M, Uberegui E, Susanti D, Schmitz RA, Mukhopadhyay B, Schürmann P, Buchanan BB. Ferredoxin:thioredoxin reductase (FTR) links the regulation of oxygenic photosynthesis to deeply rooted bacteria. PLANTA 2013; 237:619-635. [PMID: 23223880 DOI: 10.1007/s00425-012-1803-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/26/2012] [Indexed: 06/01/2023]
Abstract
Uncovered in studies on photosynthesis 35 years ago, redox regulation has been extended to all types of living cells. We understand a great deal about the occurrence, function, and mechanism of action of this mode of regulation, but we know little about its origin and its evolution. To help fill this gap, we have taken advantage of available genome sequences that make it possible to trace the phylogenetic roots of members of the system that was originally described for chloroplasts-ferredoxin, ferredoxin:thioredoxin reductase (FTR), and thioredoxin as well as target enzymes. The results suggest that: (1) the catalytic subunit, FTRc, originated in deeply rooted microaerophilic, chemoautotrophic bacteria where it appears to function in regulating CO(2) fixation by the reverse citric acid cycle; (2) FTRc was incorporated into oxygenic photosynthetic organisms without significant structural change except for addition of a variable subunit (FTRv) seemingly to protect the Fe-S cluster against oxygen; (3) new Trxs and target enzymes were systematically added as evolution proceeded from bacteria through the different types of oxygenic photosynthetic organisms; (4) an oxygenic type of regulation preceded classical light-dark regulation in the regulation of enzymes of CO(2) fixation by the Calvin-Benson cycle; (5) FTR is not universally present in oxygenic photosynthetic organisms, and in certain early representatives is seemingly functionally replaced by NADP-thioredoxin reductase; and (6) FTRc underwent structural diversification to meet the ecological needs of a variety of bacteria and archaea.
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Affiliation(s)
- Monica Balsera
- Instituto de Recursos Naturales y Agrobiología de Salamanca, Salamanca, Spain.
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