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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.


Related in: MedlinePlus

(A) Photograph of WHC2 ultra-basic pool. (B) Schematic planar and cross sectional sketches depicting the various water inputs into the WHC2 pool—A and B are locations of ultra-basic reducing water discharging into the bottom of the pool, C is the location of overland flow that trickles into WHC2.
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Figure 1: (A) Photograph of WHC2 ultra-basic pool. (B) Schematic planar and cross sectional sketches depicting the various water inputs into the WHC2 pool—A and B are locations of ultra-basic reducing water discharging into the bottom of the pool, C is the location of overland flow that trickles into WHC2.

Mentions: Water and sediments were sampled from pool WHC2 (N 49°27 ′58.7 ″ W 057°57 ′29.2 ″). This pool of water was approximately 130 cm wide and 40 cm deep surrounded by travertine deposits and was exposed to the atmosphere at the surface. Within this pool two springs located at the bottom of the pool have been identified by low Eh values and are labeled A and B (i.e., WHC2A and WHC2B) (Figure 1). A site labeled C (WHC2C) represented a mixing site where overland water from a tributary of the brook was flowing into the highly reducing pool of water. Previous work by Szponar et al. (2013) and Brazelton et al. (2012) describe the various kinds of contamination at this site and demonstrated geochemically that the sources of fluid at the bottom of the WHC2 pool are distinct from any surface sources. In June, 2011, water and sediments were sampled from WHC2A for the bicarbonate and organic acid addition experiments. In October, 2012, an artificial dam was created diverting the overland flow from WHC2C, and the WHC2 pool was emptied. Ultra-basic reducing groundwater springs recharged the pool. The pool was emptied again multiple times before pool sediments and recharging waters at WHC2A were sampled for the CO addition experiments. Geochemical field parameters (pH, Eh, sulfate, nitrate, phosphate, total inorganic carbon (TIC), δ13CTIC, dissolved organic carbon (DOC), δ13CDOC, CH4, δ13CCH4) were sampled for in 2011 and 2012.


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)

(A) Photograph of WHC2 ultra-basic pool. (B) Schematic planar and cross sectional sketches depicting the various water inputs into the WHC2 pool—A and B are locations of ultra-basic reducing water discharging into the bottom of the pool, C is the location of overland flow that trickles into WHC2.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: (A) Photograph of WHC2 ultra-basic pool. (B) Schematic planar and cross sectional sketches depicting the various water inputs into the WHC2 pool—A and B are locations of ultra-basic reducing water discharging into the bottom of the pool, C is the location of overland flow that trickles into WHC2.
Mentions: Water and sediments were sampled from pool WHC2 (N 49°27 ′58.7 ″ W 057°57 ′29.2 ″). This pool of water was approximately 130 cm wide and 40 cm deep surrounded by travertine deposits and was exposed to the atmosphere at the surface. Within this pool two springs located at the bottom of the pool have been identified by low Eh values and are labeled A and B (i.e., WHC2A and WHC2B) (Figure 1). A site labeled C (WHC2C) represented a mixing site where overland water from a tributary of the brook was flowing into the highly reducing pool of water. Previous work by Szponar et al. (2013) and Brazelton et al. (2012) describe the various kinds of contamination at this site and demonstrated geochemically that the sources of fluid at the bottom of the WHC2 pool are distinct from any surface sources. In June, 2011, water and sediments were sampled from WHC2A for the bicarbonate and organic acid addition experiments. In October, 2012, an artificial dam was created diverting the overland flow from WHC2C, and the WHC2 pool was emptied. Ultra-basic reducing groundwater springs recharged the pool. The pool was emptied again multiple times before pool sediments and recharging waters at WHC2A were sampled for the CO addition experiments. Geochemical field parameters (pH, Eh, sulfate, nitrate, phosphate, total inorganic carbon (TIC), δ13CTIC, dissolved organic carbon (DOC), δ13CDOC, CH4, δ13CCH4) were sampled for in 2011 and 2012.

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.


Related in: MedlinePlus