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Investigations of potential microbial methanogenic and carbon monoxide utilization pathways in ultra-basic reducing springs associated with present-day continental serpentinization: the Tablelands, NL, CAN.

Morrill PL, Brazelton WJ, Kohl L, Rietze A, Miles SM, Kavanagh H, Schrenk MO, Ziegler SE, Lang SQ - Front Microbiol (2014)

Bottom Line: Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present.The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰.This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, Memorial University St. John's, NL, Canada.

ABSTRACT
Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present. Very little, however, is known about the carbon substrate utilization, energy sources, and metabolic pathways of the microorganisms that live in this ultra-basic environment. The potential for microbial methanogenesis with bicarbonate, formate, acetate, and propionate precursors and carbon monoxide (CO) utilization pathways were tested in laboratory experiments by adding substrates to water and sediment from the Tablelands, NL, CAD, a site of present-day continental serpentinization. Microbial methanogenesis was not observed after bicarbonate, formate, acetate, or propionate addition. CO was consumed in the live experiments but not in the killed controls and the residual CO in the live experiments became enriched in (13)C. The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰. Phospholipid fatty acid concentrations and δ(13)C values suggest limited incorporation of carbon from CO into microbial lipids. This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth. Environmental DNA sequencing of spring fluids collected at the same time as the addition experiments yielded a large proportion of Hydrogenophaga-related sequences, which is consistent with previous metagenomic data indicating the potential for these taxa to utilize CO.

No MeSH data available.


Average relative gaseous CO concentrations (C/Co) measured over time in the CO addition experiments. Experimental treatments included killed control (Killed), live non-labeled (Live), and 13C-labeled CO (13C Live). The error bars are the standard deviation of the average value of the triplicate treatments.
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Figure 4: Average relative gaseous CO concentrations (C/Co) measured over time in the CO addition experiments. Experimental treatments included killed control (Killed), live non-labeled (Live), and 13C-labeled CO (13C Live). The error bars are the standard deviation of the average value of the triplicate treatments.

Mentions: CO concentrations were monitored in all of the nine CO utilization experimental bottles (three live 13C-labeled substrates, three live, and three killed non-labeled controls). The headspace was sampled for CO concentrations on days 2, 3, 4, 9, 30, 51, and 60 of the experiment. Concentration changes relative to day 2 measurements are shown in Figure 4. The concentrations of CO slightly increased in all live experiments on day 3, probably due to incomplete CO equilibration on day 2. Subsequently, CO concentrations decreased in all of the live bottles. By day 60, there was no detectable CO in the live 13C-labeled experiments. In the live non-labeled experiments the concentration of CO decreased by 59% in one bottle, and 65% in another. The 3rd live non-labeled was accidentally vented on day 30, such that no data could be obtained after day 9 for this experiment. However, on day 9 the concentration of CO in this bottle had decreased by 15%, comparable to the other non-labeled bottles.


Investigations of potential microbial methanogenic and carbon monoxide utilization pathways in ultra-basic reducing springs associated with present-day continental serpentinization: the Tablelands, NL, CAN.

Morrill PL, Brazelton WJ, Kohl L, Rietze A, Miles SM, Kavanagh H, Schrenk MO, Ziegler SE, Lang SQ - Front Microbiol (2014)

Average relative gaseous CO concentrations (C/Co) measured over time in the CO addition experiments. Experimental treatments included killed control (Killed), live non-labeled (Live), and 13C-labeled CO (13C Live). The error bars are the standard deviation of the average value of the triplicate treatments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230201&req=5

Figure 4: Average relative gaseous CO concentrations (C/Co) measured over time in the CO addition experiments. Experimental treatments included killed control (Killed), live non-labeled (Live), and 13C-labeled CO (13C Live). The error bars are the standard deviation of the average value of the triplicate treatments.
Mentions: CO concentrations were monitored in all of the nine CO utilization experimental bottles (three live 13C-labeled substrates, three live, and three killed non-labeled controls). The headspace was sampled for CO concentrations on days 2, 3, 4, 9, 30, 51, and 60 of the experiment. Concentration changes relative to day 2 measurements are shown in Figure 4. The concentrations of CO slightly increased in all live experiments on day 3, probably due to incomplete CO equilibration on day 2. Subsequently, CO concentrations decreased in all of the live bottles. By day 60, there was no detectable CO in the live 13C-labeled experiments. In the live non-labeled experiments the concentration of CO decreased by 59% in one bottle, and 65% in another. The 3rd live non-labeled was accidentally vented on day 30, such that no data could be obtained after day 9 for this experiment. However, on day 9 the concentration of CO in this bottle had decreased by 15%, comparable to the other non-labeled bottles.

Bottom Line: Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present.The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰.This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, Memorial University St. John's, NL, Canada.

ABSTRACT
Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present. Very little, however, is known about the carbon substrate utilization, energy sources, and metabolic pathways of the microorganisms that live in this ultra-basic environment. The potential for microbial methanogenesis with bicarbonate, formate, acetate, and propionate precursors and carbon monoxide (CO) utilization pathways were tested in laboratory experiments by adding substrates to water and sediment from the Tablelands, NL, CAD, a site of present-day continental serpentinization. Microbial methanogenesis was not observed after bicarbonate, formate, acetate, or propionate addition. CO was consumed in the live experiments but not in the killed controls and the residual CO in the live experiments became enriched in (13)C. The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰. Phospholipid fatty acid concentrations and δ(13)C values suggest limited incorporation of carbon from CO into microbial lipids. This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth. Environmental DNA sequencing of spring fluids collected at the same time as the addition experiments yielded a large proportion of Hydrogenophaga-related sequences, which is consistent with previous metagenomic data indicating the potential for these taxa to utilize CO.

No MeSH data available.