scholarly journals Predominance of hexamethylated 6-methyl branched glycerol dialkyl glycerol tetraethers in the Mariana Trench: source and environmental implication

2020 ◽  
Vol 17 (7) ◽  
pp. 2135-2148 ◽  
Author(s):  
Wenjie Xiao ◽  
Yasong Wang ◽  
Yongsheng Liu ◽  
Xi Zhang ◽  
Linlin Shi ◽  
...  
Keyword(s):  
Continental Margins ◽  
Environmental Implication ◽  
Mariana Trench ◽  
Novel Approach ◽  
Fractional Abundance ◽  
Marine Source ◽  
Marine Influence ◽  
Molecular Indicators ◽  
Trench Sediments ◽  
Glycerol Dialkyl Glycerol Tetraethers

Abstract. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are useful molecular indicators for organic carbon (OC) sources and the paleoenvironment. Their application in marine environments, however, is complicated because of a mixed terrestrial and marine source. Here, we examined brGDGTs in sediments from the Mariana Trench, the deepest ocean without significant terrestrial influence. Our result shows a strong predominance of hexamethylated 6-methyl brGDGT (IIIa′) (73.40±2.39 % of total brGDGTs) and an absence of 5-methyl brGDGTs, different from previously reported soils and marine sediments that comprised both 5-methyl and 6-methyl brGDGTs. This unique feature, combined with high δ13COC (-19.82±0.25 %), low OC∕TN ratio (6.72±0.84), low branched and isoprenoid tetraether (BIT) index (0.03±0.01), and high acyclic hexa- ∕ pentamethylated brGDGT ratio (7.13±0.98), support that brGDGTs in the Mariana Trench sediments are autochthonous rather than terrestrial products. The compiling of literature data shows that the enhanced fractional abundance of hexamethylated 6-methyl brGDGTs is a common phenomenon in continental margins when the marine influence was intensified. The cross plot of acyclic hexa- ∕ pentamethylated brGDGT ratio and fractional abundance of brGDGT IIIa′ provide a novel approach to distinguish terrestrial and marine-derived brGDGTs.

scholarly journals Predominance of hexamethylated 6-methyl branched glycerol dialkyl glycerol tetraethers in the Mariana Trench: Source and environmental implication

2019 ◽  
Author(s):  
Wenjie Xiao ◽  
Yasong Wang ◽  
Yongsheng Liu ◽  
Xi Zhang ◽  
Linlin Shi ◽  
...  
Keyword(s):  
Continental Margins ◽  
Mariana Trench ◽  
Planktonic Bacteria ◽  
Seawater Ph ◽  
Fractional Abundance ◽  
Challenger Deep ◽  
Marine Influence ◽  
Ultrahigh Performance Liquid Chromatography ◽  
Molecular Indicators ◽  
Glycerol Dialkyl Glycerol Tetraethers

Abstract. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are useful molecular indicators for organic carbon (OC) source and paleoenvironment. Their application in marine environments, however, is complicated because of the mixed terrestrial and marine contributions to brGDGTs. Here, we employ two dimensional (2D) ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS) to analyze brGDGTs in sediments from the Challenger Deep, Mariana Trench, the deepest ocean in the absent of terrestrial influence. The unique feature is the absence of 5-methyl brGDGTs, and the strong predominance of hexamethylated 6-methyl brGDGT (IIIa') (73.4 ±2.4 % of total brGDGTs). The brGDGTs-reconstructed pH is 8.22 ± 0.07, close to seawater pH. This, combined with characteristics of δ13C (− 19.82 ± 0.25 %), OC / TN ratio (6.72 ± 0.84), branched and isoprenoid tetraether (BIT) index (0.03 ± 0.01) and the acyclic hexa-/pentamethylated brGDGTs ratio (7.13 ± 0.98), strongly suggest that brGDGTs are of autochthonous products from benthic bacteria or planktonic bacteria. The compiling of literature data reveals that enhanced fractional abundance of hexamethylated 6-methyl brGDGTs is common in diverse continental margins when the marine influence became intensified. This may reflect an adaption of brGDGTs-producing bacteria to weak alkaline seawater and low ambient temperature. Based on the global dataset, the cross plot of acyclic hexa-/pentamethylated brGDGTs ratio and fractional abundance of brGDGT-IIIa' is an effective approach to distinguish the terrestrial vs. marine provenance of brGDGTs.

scholarly journals Composition of Sedimentary Organic Matter across the Laptev Sea Shelf: Evidences from Rock-Eval Parameters and Molecular Indicators

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3511
Author(s):  
Elena Gershelis ◽  
Andrey Grinko ◽  
Irina Oberemok ◽  
Elizaveta Klevantseva ◽  
Natalina Poltavskaya ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Sediments ◽  
Continental Margins ◽  
Laptev Sea ◽  
Lena River ◽  
Nearshore Sediments ◽  
Rock Eval ◽  
Molecular Indicators ◽  
Sedimentation Regime ◽  
The Laptev Sea

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback to climate change. In the present study, we aim to identify the sources, distribution and degradation state of organic matter (OM) stored in the surface sediments of the Laptev Sea (LS), which receives a large input of terrestrial carbon from both Lena River discharge and intense coastal erosion. We applied a suite of geochemical indicators including the Rock Eval parameters, traditionally used for the matured OM characterization, and terrestrial lipid biomarkers. In addition, we analyzed a comprehensive grain size data in order to assess hydrodynamic sedimentation regime across the LS shelf. Rock-Eval (RE) data characterize LS sedimentary OM with generally low hydrogen index (100–200 mg HC/g TOC) and oxygen index (200 and 300 CO2/g TOC) both increasing off to the continental slope. According to Tpeak values, there is a clear regional distinction between two groups (369–401 °C for the inner and mid shelf; 451–464 °C for the outer shelf). We suggest that permafrost-derived OM is traced across the shallow and mid depths with high Tpeak and slightly elevated HI values if compared to other Arctic continental margins. Molecular-based degradation indicators show a trend to more degraded terrestrial OC with increasing distance from the coast corroborating with RE results. However, we observed much less variation of the degradation markers down to the deeper sampling horizons, which supports the notion that the most active OM degradation in LS land-shelf system takes part during the cross-shelf transport, not while getting buried deeper.

Dermacozines H–J Isolated from a Deep-Sea Strain of Dermacoccus abyssi from Mariana Trench Sediments

2014 ◽  
Vol 77 (2) ◽  
pp. 416-420 ◽  
Author(s):  
Marcell Wagner ◽  
Wael M. Abdel-Mageed ◽  
Rainer Ebel ◽  
Alan T. Bull ◽  
Michael Goodfellow ◽  
...  
Keyword(s):  
Deep Sea ◽  
Mariana Trench ◽  
Trench Sediments

scholarly journals Distribution of branched glycerol dialkyl glycerol tetraethers in surface soils of the Qinghai–Tibetan Plateau: implications of brGDGTs-based proxies in cold and dry regions

2015 ◽  
Vol 12 (11) ◽  
pp. 3141-3151 ◽  
Author(s):  
S. Ding ◽  
Y. Xu ◽  
Y. Wang ◽  
Y. He ◽  
J. Hou ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Soil Ph ◽  
Soil Bacteria ◽  
Global Climate ◽  
Large Area ◽  
Ph Change ◽  
Surface Soils ◽  
Methylation Index ◽  
Fractional Abundance ◽  
Glycerol Dialkyl Glycerol Tetraethers

Abstract. The methylation index of branched tetraethers (MBT) and cyclization ratio of branched tetraethers (CBT) based on the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGT) are useful proxies for the reconstruction of mean annual air temperature (MAT) and soil pH. Recently, a series of 6-methyl brGDGTs were identified which were previously co-eluted with 5-methyl brGDGTs. However, little is known about 6-methyl brGDGTs in the Qinghai–Tibetan Plateau (QTP), a critical region of the global climate system. Here, we analyze 30 surface soils covering a large area of the QTP, among which 6-methyl brGDGTs were the most abundant components (average 53 ± 17% of total brGDGT). The fractional abundance of 6-methyl brGDGTs showed a good correlation with soil pH, while the global MBT'5ME calibration overestimates MAT in the QTP. We therefore proposed a MBT5/6 index including both 5- and 6-methyl brGDGTs, presenting a strong correlation with MAT in QTP: MAT = −20.14 + 39.51 × MBT5/6 (n = 27, r2 = 0.82; RMSE = 1.3 °C). Another index, namely IBT (isomerization of branched tetraether), based on carbon skeleton isomerization of the 5-methyl to 6-methyl brGDGTs, is dependent on soil pH: pH = 6.77 − 1.56 × IBT (n = 27; r2 = 0.74, RMSE = 0.32). Our study suggests that changing the position of methyl group of brGDGTs may be another mechanism for some soil bacteria to adapt to the ambient pH change in addition to the well-known cyclization.

scholarly journals Bioactive Metabolites from the Mariana Trench Sediment-Derived Fungus Penicillium sp. SY2107

Marine Drugs ◽  
2020 ◽  
Vol 18 (5) ◽  
pp. 258 ◽  
Author(s):  
Sidra Kaleem ◽  
Le Qin ◽  
Wenwen Yi ◽  
Xiao-Yuan Lian ◽  
Zhizhen Zhang
Keyword(s):  
Antimicrobial Activities ◽  
Bioactive Metabolites ◽  
Ionization Mass ◽  
X Ray Diffraction ◽  
Mariana Trench ◽  
Penicillium Sp ◽  
Electrospray Ionization Mass Spectroscopy ◽  
Ionization Mass Spectroscopy ◽  
Rice Medium ◽  
Trench Sediments

Mariana Trench sediments are enriched in microorganisms, however, the structures and bioactivities of their secondary metabolites are not very known. In this study, a fungus Penicillium sp. SY2107 was isolated from a sample of Mariana Trench sediment collected at a depth of 11000 m and an extract prepared from the culture of this fungus in rice medium showed antimicrobial activities. Chemical investigation on this active extract led to the isolation of 16 compounds, including one novel meroterpenoid, named andrastone C. Structure of the new compound was elucidated based on high-resolution electrospray ionization mass spectroscopy (HRESIMS) data, extensive nuclear magnetic resonance (NMR) spectroscopic analyses and a single crystal X-ray diffraction. The crystal structure of a known meroterpenoid andrastone B was also reported in this study. Both andrastones B and C exhibited antimicrobial activities against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans with minimum inhibitory concentration (MIC) values in a range from 6 to 13 μg/mL.

scholarly journals The Capability of Utilizing Abiotic Enantiomers of Amino Acids by Halomonas sp. LMO_D1 Derived From the Mariana Trench

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiangyu Wang ◽  
Yi Yang ◽  
Yongxin Lv ◽  
Xiang Xiao ◽  
Weishu Zhao
Keyword(s):  
Amino Acids ◽  
Subduction Zones ◽  
Fosmid Library ◽  
Mariana Trench ◽  
Amino Acid Dehydrogenase ◽  
Degradation Activity ◽  
Essential Function ◽  
Microbial Potential ◽  
Trench Sediments ◽  
Library Method

D-amino acids (D-AAs) have been produced both in organisms and in environments via biotic or abiotic processes. However, the existence of these organic materials and associated microbial degradation activity has not been previously investigated in subduction zones where tectonic activities result in the release of hydrothermal organic matter. Here, we isolated the bacterium Halomonas sp. LMO_D1 from a sample obtained from the Mariana trench, and we determined that this isolate utilized 13 different D-AAs (D-Ala, D-Glu, D-Asp, D-Ser, D-Leu, D-Val, D-Tyr, D-Gln, D-Asn, D-Pro, D-Arg, D-Phe, and D-Ile) in the laboratory and could grow on D-AAs under high hydrostatic pressure (HHP). Moreover, the metabolism of L-AAs was more severely impaired under HHP conditions compared with that of their enantiomers. The essential function gene (Chr_2344) required for D-AA catabolism in strain LMO_D1 was identified and confirmed according to the fosmid library method used on the D-AAs plate. The encoded enzyme of this gene (DAADH_2344) was identified as D-amino acid dehydrogenase (DAADH), and this gene product supports the catabolism of a broad range of D-AAs. The ubiquitous distribution of DAADHs within the Mariana Trench sediments suggests that microorganisms that utilize D-AAs are common within these sediments. Our findings provide novel insights into the microbial potential for utilizing abiotic enantiomers of amino acids within the subduction zone of the Mariana trench under HHP, and our results provide an instructive significance for understanding these abiotic enantiomers and allow for insights regarding how organisms within extraterrestrial HHP environments can potentially cope with toxic D-AAs.

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