scholarly journals Efficient removal of recalcitrant deep-ocean dissolved organic matter during hydrothermal circulation

2015 ◽  
Vol 8 (11) ◽  
pp. 856-860 ◽  
Author(s):  
Jeffrey A. Hawkes ◽  
Pamela E. Rossel ◽  
Aron Stubbins ◽  
David Butterfield ◽  
Douglas P. Connelly ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Deep Ocean ◽  
Hydrothermal Circulation ◽  
Efficient Removal

Efficient export of carbon to the deep ocean through dissolved organic matter

Nature ◽  
2005 ◽  
Vol 433 (7022) ◽  
pp. 142-145 ◽  
Author(s):  
Charles S. Hopkinson ◽  
Joseph J. Vallino
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Deep Ocean

scholarly journals Picocyanobacteria and deep-ocean fluorescent dissolved organic matter share similar optical properties

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Zhao Zhao ◽  
Michael Gonsior ◽  
Jenna Luek ◽  
Stephen Timko ◽  
Hope Ianiri ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Deep Ocean ◽  
Fluorescent Dissolved Organic Matter

scholarly journals SAR202 Genomes from the Dark Ocean Predict Pathways for the Oxidation of Recalcitrant Dissolved Organic Matter

mBio ◽  
2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Zachary Landry ◽  
Brandon K. Swan ◽  
Gerhard J. Herndl ◽  
Ramunas Stepanauskas ◽  
Stephen J. Giovannoni
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Complex Mixture ◽  
Deep Ocean ◽  
Oxidative Enzymes ◽  
Flavin Mononucleotide ◽  
Biological Oxidation ◽  
Refractory Compounds ◽  
Cyclic Alkanes ◽  
Oxygen Insertion

ABSTRACTDeep-ocean regions beyond the reach of sunlight contain an estimated 615 Pg of dissolved organic matter (DOM), much of which persists for thousands of years. It is thought that bacteria oxidize DOM until it is too dilute or refractory to support microbial activity. We analyzed five single-amplified genomes (SAGs) from the abundant SAR202 clade of dark-ocean bacterioplankton and found they encode multiple families of paralogous enzymes involved in carbon catabolism, including several families of oxidative enzymes that we hypothesize participate in the degradation of cyclic alkanes. The five partial genomes encoded 152 flavin mononucleotide/F420-dependent monooxygenases (FMNOs), many of which are predicted to be type II Baeyer-Villiger monooxygenases (BVMOs) that catalyze oxygen insertion into semilabile alicyclic alkanes. The large number of oxidative enzymes, as well as other families of enzymes that appear to play complementary roles in catabolic pathways, suggests that SAR202 might catalyze final steps in the biological oxidation of relatively recalcitrant organic compounds to refractory compounds that persist.IMPORTANCECarbon in the ocean is massively sequestered in a complex mixture of biologically refractory molecules that accumulate as the chemical end member of biological oxidation and diagenetic change. However, few details are known about the biochemical machinery of carbon sequestration in the deep ocean. Reconstruction of the metabolism of a deep-ocean microbial clade, SAR202, led to postulation of new biochemical pathways that may be the penultimate stages of DOM oxidation to refractory forms that persist. These pathways are tied to a proliferation of oxidative enzymes. This research illuminates dark-ocean biochemistry that is broadly consequential for reconstructing the global carbon cycle.

scholarly journals Deep-ocean dissolved organic matter reactivity along the Mediterranean Sea: does size matter?

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Alba María Martínez-Pérez ◽  
Xosé Antón Álvarez-Salgado ◽  
Javier Arístegui ◽  
Mar Nieto-Cid
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Deep Ocean ◽  
The Mediterranean ◽  
Size Matter

scholarly journals Illuminating microbial metabolic activities in the dark deep ocean with metaproteomics

2018 ◽  
Author(s):  
Zhang-Xian Xie ◽  
Shu-Feng Zhang ◽  
Hao Zhang ◽  
Ling-Fen Kong ◽  
Lin Lin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Community ◽  
Dissolved Organic Matter ◽  
Metabolic Activity ◽  
Deep Ocean ◽  
Viral Proteins ◽  
Life Forms ◽  
Cytoplasmic Proteins ◽  
Proteomic Study ◽  
Metabolic Activities

AbstractThe deep ocean is the largest habitat on earth and holds diverse microbial life forms. Significant advances have been made in microbial diversity and their genomic potential in the deep ocean, however, little is known about microbial metabolic activity that is crucial to regulate the bathypelagic carbon sequestration. Here, we characterized proteomes covering large particulate (>0.7 μm), small particulate (0.2-0.7 μm) and dissolved (10 kDa-0.2 μm) fractions collected at a depth of 3000 m in the South China Sea. The Rhodospirillales, SAR324, SAR11, Nitrosinae/Tectomicrobia were the major contributors in the particulate fraction whereas Alteromonadales and viruses dominated the dissolved counterpart. Frequent detection of transcription or translation proteins in the particulate fractions indicated active metabolism of SAR324, Archaea, SAR11, and possible viable surface microbes, e.g. Prochlorococcus. Transporters for diverse substrates were the most abundant functional groups, and numerous spectra of formate dehydrogenases and glycine betaine transporters unveiled the importance of methylated compounds for the survival of deep-sea microbes. Notably, abundant non-viral proteins, especially transporters and cytoplasmic proteins, were detected in the dissolved fraction, indicating their potential roles in nutrient scavenging and the stress response. Our size-based proteomic study implied the holistic microbial activity mostly acting on the labile dissolved organic matter as well as the potential activities of surface microbes and dissolved non-viral proteins in the deep ocean.ImportanceThe deep ocean produces one third of the biological CO2 in the ocean. However, little is known about metabolic activity of the bathypelagic microbial community which is crucial for understanding the biogeochemical cycling of organic matter, especially the formation of bulk refractory dissolved organic matter (DOM), one of the largest reservoirs of reduced carbon on Earth. This study provided the protein evidence firstly including both particulate and dissolved fractions to comprehensively decipher the active microbes and metabolic processes involved in the DOM recycling in the deep ocean. Our data supported the hypothesis of the carbon and energy supply from the labile DOM after the solution of sinking particles to the bathypelagic microbial community.

scholarly journals What can we learn from amino acids about oceanic organic matter cycling and degradation?

2021 ◽  
Author(s):  
Birgit Gaye ◽  
Niko Lahajnar ◽  
Natalie Harms ◽  
Sophie Anna Luise Paul ◽  
Tim Rixen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Water Column ◽  
Deep Ocean ◽  
Principal Component ◽  
Suspended Particles ◽  
Organic Matter Cycling ◽  
Biogeochemical Indicators ◽  
Chemical Conditions

Abstract. Amino acids (AA) mainly bound in proteins are major constituents of living biomass and non-living organic material in the oceanic particulate and dissolved organic matter pool. Uptake and cycling by heterotrophic organisms lead to characteristic changes in AA composition so that AA based biogeochemical indicators are often used to elucidate processes of organic matter cycling and degradation. We analyzed particulate AA in a large sample set collected in various oceanic regions covering sinking and suspended particles in the water column, sediment samples as well as dissolved AA from water column and pore water samples. The aim of this study was to test and improve the use of AA derived biogeochemical indicators as proxies for organic matter sources and degradation, and to better understand particle dynamics and interaction between the dissolved and particulate organic matter pools. A principal component analysis (PCA) of all data delineates diverging AA compositions of sinking and suspended particles with increasing water depth. A new sinking particle and sediment degradation indicator (SDI) allows a fine-tuned classification of sinking particles and sediments with respect to the intensity of degradation, which is associated with changes of bulk δ15N ratios. This new indicator furthermore is sensitive to sedimentary redox conditions and can be used to detect past anoxic early diagenesis. A second indicator emerges from the AA spectra of suspended particulate matter (SPM) in the epipelagic and that of the meso- and bathypelagic ocean and is a residence time indicator (RTI). The characteristic changes in AA patterns from shallow to deep SPM are recapitulated in the AA spectra of the dissolved organic matter (DOM) pool, so that deep SPM is more similar to DOM than to any of the other organic matter pools. This implies that there is equilibration between finely dispersed SPM and DOM in the deep sea, which may be driven by microbial activity combined with annealing and fragmentation of gels. As these processes strongly depend on physico-chemical conditions in the deep ocean, changes in quality and degradability of DOM may strongly affect the relatively large pool of suspended and dissolved AA in the ocean that amounts to 15 Pg amino acid carbon (AAC) and 89 ± 29 Pg AAC, respectively.  

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