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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 stable carbon isotope values of CO in the headspace of non-labeled CO utilization experiments of live and killed control treatments. The error bars are the standard deviation of the average value of the triplicate treatments. Significant isotopic enrichment of 13C in CO was only observed in the live experiments and not the killed controls.
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Figure 5: Average stable carbon isotope values of CO in the headspace of non-labeled CO utilization experiments of live and killed control treatments. The error bars are the standard deviation of the average value of the triplicate treatments. Significant isotopic enrichment of 13C in CO was only observed in the live experiments and not the killed controls.

Mentions: The average starting δ13C of CO in the non-labeled experiments was −44.4 ±0.5‰. Over the course of the experiments the δ13C of CO in the live experiments became less negative with an average increase of 10 ± 0.3‰ between day 2 and day 60 (Figure 5). This isotopic enrichment in 13C corresponds to a 59–65% decrease in the CO concentrations in these experiments. Conversely, over the course of the killed non-13C-labeled control experiments, the δ13C of CO increased on average by 1.3 ± 0.2‰ between day 2 and day 60, and there was no decrease in relative CO concentrations over this period of time.


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 stable carbon isotope values of CO in the headspace of non-labeled CO utilization experiments of live and killed control treatments. The error bars are the standard deviation of the average value of the triplicate treatments. Significant isotopic enrichment of 13C in CO was only observed in the live experiments and not the killed controls.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Average stable carbon isotope values of CO in the headspace of non-labeled CO utilization experiments of live and killed control treatments. The error bars are the standard deviation of the average value of the triplicate treatments. Significant isotopic enrichment of 13C in CO was only observed in the live experiments and not the killed controls.
Mentions: The average starting δ13C of CO in the non-labeled experiments was −44.4 ±0.5‰. Over the course of the experiments the δ13C of CO in the live experiments became less negative with an average increase of 10 ± 0.3‰ between day 2 and day 60 (Figure 5). This isotopic enrichment in 13C corresponds to a 59–65% decrease in the CO concentrations in these experiments. Conversely, over the course of the killed non-13C-labeled control experiments, the δ13C of CO increased on average by 1.3 ± 0.2‰ between day 2 and day 60, and there was no decrease in relative CO concentrations over this period of time.

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.