scholarly journals CO2conversion to methane and biomass in obligate methylotrophic methanogens in marine sediments

2019 ◽  
Author(s):  
Xiuran Yin ◽  
Weichao Wu ◽  
Mara Maeke ◽  
Tim Richter-Heitmann ◽  
Ajinkya C. Kulkarni ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Metabolic Pathways ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Methanogenic Archaea ◽  
Stable Isotope Probing ◽  
Optimal Conditions ◽  
Carbon Utilization ◽  
Area North ◽  
Mud Area

AbstractMethyl substrates are important compounds for methanogenesis in marine sediments but diversity and carbon utilization by methylotrophic methanogenic archaea have not been clarified. Here, we demonstrate that RNA-stable isotope probing (SIP) requires13C-labeled bicarbonate as co-substrate for identification of methylotrophic methanogens in sediment samples of the Helgoland mud area, North Sea. Using lipid-SIP, we found that methylotrophic methanogens incorporate 60 to 86% of dissolved inorganic carbon (DIC) into lipids, and thus considerably more than what can be predicted from known metabolic pathways (∼40% contribution). In slurry experiments amended with the marine methylotrophMethanococcoides methylutens, up to 12% of methane was produced from CO2, indicating that CO2-dependent methanogenesis is an alternative methanogenic pathway and suggesting that obligate methylotrophic methanogens grow in fact mixotrophically on methyl compounds and DIC. Thus, the observed high DIC incorporation into lipds is likely linked to CO2-dependent methanogenesis, which was triggered when methane production rates were low. Since methylotrophic methanogenesis rates are much lower in marine sediments than under optimal conditions in pure culture, CO2conversion to methane is an important but previously overlooked methanogenic process in sediments for methylotrophic methanogens.

scholarly journals Subgroup level differences of physiological activities in marine Lokiarchaeota

2020 ◽  
Author(s):  
Xiuran Yin ◽  
Mingwei Cai ◽  
Yang Liu ◽  
Guowei Zhou ◽  
Tim Richter-Heitmann ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Marine Sediments ◽  
Inorganic Carbon ◽  
Bacterial Biomass ◽  
Stable Isotope Probing ◽  
Aromatic Compound Degradation ◽  
Lactate Degradation ◽  
Globally Distributed ◽  
Mud Area

Abstract Asgard is a recently discovered archaeal superphylum, closely linked to the emergence of eukaryotes. Among Asgard archaea, Lokiarchaeota are abundant in marine sediments, but their in situ activities are largely unknown except for Candidatus ‘Prometheoarchaeum syntrophicum’. Here, we tracked the activity of Lokiarchaeota in incubations with Helgoland mud area sediments (North Sea) by stable isotope probing (SIP) with organic polymers, 13C-labelled inorganic carbon, fermentation intermediates and proteins. Within the active archaea, we detected members of the Lokiarchaeota class Loki-3, which appeared to mixotrophically participate in the degradation of lignin and humic acids while assimilating CO2, or heterotrophically used lactate. In contrast, members of the Lokiarchaeota class Loki-2 utilized protein and inorganic carbon, and degraded bacterial biomass formed in incubations. Metagenomic analysis revealed pathways for lactate degradation, and involvement in aromatic compound degradation in Loki-3, while the less globally distributed Loki-2 instead rely on protein degradation. We conclude that Lokiarchaeotal subgroups vary in their metabolic capabilities despite overlaps in their genomic equipment, and suggest that these subgroups occupy different ecologic niches in marine sediments.

Comparative study of dissolved inorganic carbon utilization and photosynthetic responses in Nannochloris (Chlorophyceae) and Nannochloropsis (Eustigmatophyceae) species

1998 ◽  
Vol 76 (6) ◽  
pp. 1104-1108 ◽  
Author(s):  
I Emma Huertas ◽  
Luis M Lubián
Keyword(s):  
Life Cycle ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Nannochloropsis Oculata ◽  
Marine Phytoplankton ◽  
Bicarbonate Transport ◽  
Photosynthetic Oxygen Evolution ◽  
Carbon Utilization ◽  
Nannochloropsis Gaditana ◽  
Inorganic Carbon Utilization

Four species of marine microalgae with similar morphology and life cycle, namely Nannochloris atomus Butcher, Nannochloris maculata Butcher, Nannochloropsis gaditana Lubian, and Nannochloropsis oculata (Droop) Hibberd, have been examined with respect to their affinity for different sources of dissolved inorganic carbon. External carbonic anhydrase activity was not found in any of these species, but the cell affinity for dissolved inorganic carbon (DIC) in Nannochloris species was affected by the inhibitor acetazolamide at a concentration of 400 µM. Measurement of photosynthetic rates and CO2 compensation points at different pH values showed that the Nannochloris species had a greater capacity for CO2 rather than HCO3- utilization. In contrast, the observed rates of photosynthetic oxygen evolution in Nannochloropsis species were greater than could be accounted for by the theoretical rate of CO2 supply from the spontaneous dehydration of bicarbonate in the external medium. This indicates that these algae were able to transport bicarbonate across the plasmalemma. Furthermore, the K0.5 (DIC) value at acidic pH showed that Nannochloropsis oculata could also use CO2 as an exogenous carbon source for photosynthesis. Although the species of marine phytoplankton used in this study possess similar morphological characteristics and life cycle, there exist many differences in the mode of inorganic carbon utilization between these microalgae.Key words: Nannochloris, Nannochloropsis, inorganic carbon utilization, bicarbonate transport, CO2 compensation point, photosynthesis.

scholarly journals Ubiquitous Dissolved Inorganic Carbon Assimilation by Marine Bacteria in the Pacific Northwest Coastal Ocean as Determined by Stable Isotope Probing

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e46695 ◽  
Author(s):  
Suzanne DeLorenzo ◽  
Suzanna L. Bräuer ◽  
Chelsea A. Edgmont ◽  
Lydie Herfort ◽  
Bradley M. Tebo ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Pacific Northwest ◽  
Marine Bacteria ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Assimilation ◽  
Coastal Ocean ◽  
Stable Isotope Probing ◽  
The Pacific

scholarly journals Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change

2013 ◽  
Vol 10 (1) ◽  
pp. 371-398 ◽  
Author(s):  
V. Krumins ◽  
M. Gehlen ◽  
S. Arndt ◽  
P. Van Cappellen ◽  
P. Regnier
Keyword(s):  
Organic Carbon ◽  
Marine Sediments ◽  
Reactive Transport ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Transport Processes ◽  
Coastal Marine Sediments ◽  
Coastal Marine ◽  
Depositional Flux ◽  
Particulate Inorganic Carbon

Abstract. We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation, while the reactions included are the redox pathways of organic carbon oxidation, re-oxidation of reduced nitrogen, iron and sulfur compounds, pore water acid-base equilibria, and dissolution of particulate inorganic carbon (calcite, aragonite, and Mg-calcite). The coastal zone is divided into four environmental units with different particulate inorganic carbon (PIC) and particulate organic carbon (POC) fluxes: reefs, banks and bays, carbonate shelves and non-carbonate shelves. Model results are analyzed separately for each environment and then scaled up to the whole coastal ocean. The model-derived estimate for the present-day global coastal benthic DIC efflux is 126 Tmol yr−1, based on a global coastal reactive POC depositional flux of 117 Tmol yr−1. The POC decomposition leads to a carbonate dissolution from shallow marine sediments of 7 Tmol yr−1 (on the order of 0.1 Pg C yr−1. Assuming complete re-oxidation of aqueous sulfide released from sediments, the effective net flux of alkalinity to the water column is 29 Teq. yr−1, primarily from PIC dissolution (46%) and ammonification (33%). Because our POC depositional flux falls in the high range of global values given in the literature, the reported DIC and alkalinity fluxes should be viewed as upper-bound estimates. Increasing coastal seawater DIC to what might be expected in year 2100 due to the uptake of anthropogenic CO2 increases PIC dissolution by 2.3 Tmol yr−1and alkalinity efflux by 4.8 Teq. yr−1. Our reactive transport modeling approach not only yields global estimates of benthic DIC, alkalinity and nutrient fluxes under variable scenarios of ocean productivity and chemistry, but also provides insights into the underlying processes.

scholarly journals Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change

2012 ◽  
Vol 9 (7) ◽  
pp. 8475-8539 ◽  
Author(s):  
V. Krumins ◽  
M. Gehlen ◽  
S. Arndt ◽  
P. van Cappellen ◽  
P. Regnier
Keyword(s):  
Organic Carbon ◽  
Marine Sediments ◽  
Reactive Transport ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Transport Processes ◽  
Coastal Marine Sediments ◽  
Coastal Marine ◽  
Depositional Flux ◽  
Particulate Inorganic Carbon

Abstract. We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation, while the reactions included are the redox pathways of organic carbon oxidation, re-oxidation of reduced nitrogen, iron and sulfur compounds, pore water acid-base equilibria, and dissolution of particulate inorganic carbon (calcite, aragonite, and Mg-calcite). The coastal zone is divided into four environmental units with different particulate inorganic carbon (PIC) and particulate organic carbon (POC) fluxes: reefs, banks and bays, carbonate shelves and non-carbonate shelves. Model results are analyzed separately for each environment and then scaled up to the whole coastal ocean. The model-derived estimate for the present-day global coastal benthic DIC efflux is 126 Tmol yr−1, based on a global coastal reactive POC depositional flux of 117 Tmol yr−1. The POC decomposition leads to a~carbonate dissolution from shallow marine sediments of 7 Tmol yr−1 (on the order of 0.1 Pg C yr−1). Assuming complete re-oxidation of aqueous sulfide released from sediments, the effective net flux of alkalinity to the water column is 29 Teq yr−1, primarily from PIC dissolution (46%) and ammonification (33%). Because our POC depositional flux falls in the high range of global values given in the literature, the reported DIC and alkalinity fluxes should be viewed as upper-bound estimates. Increasing coastal seawater DIC to what might be expected in year 2100 due to the uptake of anthropogenic CO2 increases PIC dissolution by 2.3 Tmol yr−1 and alkalinity efflux by 4.8 Teq yr−1. Our reactive transport modeling approach not only yields global estimates of benthic DIC, alkalinity and nutrient fluxes under variable scenarios of ocean productivity and chemistry, but also provides insights into the underlying processes.

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