Productivity-diversity relationships from chemolithoautotrophically based sulfidic karst systems

Porter, Megan L.; Engel, Annette Summers; Kane, Thomas C.; Kinkle, Brian K.

doi:10.5038/1827-806x.38.1.4

Cited by 74 publications

(56 citation statements)

References 69 publications

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“…All 8 of our sequences shared > 95% sequence identity with a sequence obtained from similar incubation experiments conducted in the Baltic Sea (AJ810529) (Brettar et al 2006, A. Burgin unpubl. data) and were identical to other environmental sequences recovered from freshwater, anoxic, and sulfidic environments (Briée et al 2007, Amaral-Zettler et al 2008, Porter et al 2009 (Fig. 5).…”

Section: Bacterial Population Response To No 3 − Additionsupporting

confidence: 52%

Denitrification by sulfur-oxidizing bacteria in a eutrophic lake

Burgin

Hamilton

Jones

et al. 2012

Aquat. Microb. Ecol.

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Understanding the mechanistic controls of microbial denitrification is of central importance to both environmental microbiology and ecosystem ecology. Loss of nitrate (NO 3 − ) is often attributed to carbon-driven (heterotrophic) denitrification. However, denitrification can also be coupled to sulfur (S) oxidation by chemolithoautotrophic bacteria. In the present study, we used an in situ stable isotope ( 15 NO 3 − ) tracer addition in combination with molecular approaches to understand the contribution of sulfur-oxidizing bacteria to the reduction of NO 3 − in a eutrophic lake. Samples were incubated across a total dissolved sulfide (H 2 S) gradient (2 to 95 µM) between the lower epilimnion and the upper hypolimnion. Denitrification rates were low at the top of the chemocline (4.5 m) but increased in the deeper waters (5.0 and 5.5 m), where H 2 S was abundant. Concomitant with increased denitrification at depths with high sulfide was the production of sulfate (SO 4 2− ), suggesting that the added NO 3 − was used to oxidize H 2 S to SO 4 2− . Alternative nitrate removal pathways, including dissimilatory nitrate reduction to ammonium (DNRA) and anaerobic ammonium oxidation (anammox), did not systematically change with depth and accounted for 1 to 15% of the overall nitrate loss. Quantitative PCR revealed that bacteria of the Sulfurimonas genus that are known denitrifiers increased in abundance in response to NO 3 − addition in the treatments with higher H 2 S. Stoichiometric estimates suggest that H 2 S oxidation accounted for more than half of the denitrification at the depth with the highest sulfide concentration. The present study provides evidence that microbial coupling of S and nitrogen (N) cycling is likely to be important in eutrophic freshwater ecosystems.KEY WORDS: Denitrification · Nitrate reduction · Sulfur oxidation · Sulfur-driven denitrification · Sulfurimonas denitrificans · Sulfide · Wintergreen Lake Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 66: [283][284][285][286][287][288][289][290][291][292][293] 2012 Anaerobic sediments and biofilms of aquatic ecosystems are conducive to NO 3 − reduction; however, 15 N tracer studies often show that less than half of the total NO 3 − disappearance is attributable to direct denitrification (e.g. Mulholland et al. 2008). Such findings suggest that other microbial processes may be important for removing NO 3 − in freshwater ecosystems (Gardner et al. 2006, Burgin & Hamilton 2007, Gardner & McCarthy 2009. NO 3 − can also be reduced via dissimilatory nitrate reduction (DNRA) to ammonium (NH 4 + ) by fermentative bacteria as well as via denitrification or DNRA coupled to the chemolithoautotrophic oxidation of either sulfur (Brunet & Garcia-Gil 1996, Otte et al. 1999 or iron (Weber et al. 2006). The relative importance of DNRA and denitrification is germane to understanding the fate of NO 3 − because the NH 4 + produced by DNRA is biologically available, while N 2 , the predominant end-produc...

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Section: Bacterial Population Response To No 3 − Additionsupporting

confidence: 52%

Denitrification by sulfur-oxidizing bacteria in a eutrophic lake

Burgin

Hamilton

Jones

et al. 2012

Aquat. Microb. Ecol.

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“…Porter et al (2009) indicate that at least 30% of the autotrophically fixed carbon in Lower Kane Cave microbial mats is cycled through a microbial detrital loop. From 0 to 10 s (B190-195 m), where measured C T S ¼ values are only slightly lower than expected (given experimental error) from the first-order loss curve (Figure 5c), the d…”

Section: Discussionmentioning

confidence: 99%

Linking phylogenetic and functional diversity to nutrient spiraling in microbial mats from Lower Kane Cave (USA)

et al. 2009

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Microbial mats in sulfidic cave streams offer unique opportunities to study redox-based biogeochemical nutrient cycles. Previous work from Lower Kane Cave, Wyoming, USA, focused on the aerobic portion of microbial mats, dominated by putative chemolithoautotrophic, sulfuroxidizing groups within the Epsilonproteobacteria and Gammaproteobacteria. To evaluate nutrient cycling and turnover within the whole mat system, a multidisciplinary strategy was used to characterize the anaerobic portion of the mats, including application of the full-cycle rRNA approach, the most probable number method, and geochemical and isotopic analyses. Seventeen major taxonomic bacterial groups and one archaeal group were retrieved from the anaerobic portions of the mats, dominated by Deltaproteobacteria and uncultured members of the Chloroflexi phylum. A nutrient spiraling model was applied to evaluate upstream to downstream changes in microbial diversity based on carbon and sulfur nutrient concentrations. Variability in dissolved sulfide concentrations was attributed to changes in the abundance of sulfide-oxidizing microbial groups and shifts in the occurrence and abundance of sulfate-reducing microbes. Gradients in carbon and sulfur isotopic composition indicated that released and recycled byproduct compounds from upstream microbial activities were incorporated by downstream communities. On the basis of the type of available chemical energy, the variability of nutrient species in a spiraling model may explain observed differences in microbial taxonomic affiliations and metabolic functions, thereby spatially linking microbial diversity to nutrient spiraling in the cave stream ecosystem.

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“…In contrast to the most typical subaerial, light-driven primary producer communities, underground microbes require a chemosynthetic metabolism for primary productivity, perhaps relying on the oxidation of sulfur and iron compounds to support growth and continuity, as these are the main energy sources in such environments (Sarbu et al 1996;Chen et al 2009;Porter et al 2009). Because these metabolic pathways are less energetic than photosynthesis, life underground is expected to have been slow-growing, less dynamic in terms of diversity and interactions, and more geographically contained than, for example, subaerial phototrophs.…”

Section: Underground Realmmentioning

confidence: 99%

Early life on land and the first terrestrial ecosystems

Beraldi-Campesi¹

2013

Ecol Process

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Terrestrial ecosystems have been largely regarded as plant-dominated land surfaces, with the earliest records appearing in the early Phanerozoic (<550 Ma). Yet the presence of biological components in pre-Phanerozoic rocks, in habitats as different as soils, peats, ponds, lakes, streams, and dune fields, implies a much earlier type of terrestrial ecosystems. Microbes were abundant by~3,500 Ma ago and surely adapted to live in subaerial conditions in coastal and inland environments, as they do today. This implies enormous capacities for rapid adaptations to changing conditions, which is supported by a suggestive fossil record. Yet, evidence of "terrestrial" microbes is rare and indirect in comparison with fossils from shallow or deeper marine environments, and its record has been largely overlooked. Consequently, the notion that microbial communities may have formed the earliest land ecosystems has not been widely accepted nor integrated into our general knowledge. Currently, an ample record of shallow marine and lacustrine biota in~3,500 Ma-old deposits, together with evidence of microbial colonization of coastal environments~3,450 Ma ago and indirect geochemical evidence that suggests biological activity in >3,400 Ma-old paleosols endorses the idea that life on land perhaps occurred in parallel with aquatic life back in the Paleoarchean. The rapid adaptations seen in modern terrestrial microbes, their outstanding tolerance to extreme and fluctuating conditions, their early and rapid diversification, and their old fossil record collectively suggest that they constituted the earliest terrestrial ecosystems, at least since the Neoarchean, further succeeding on land and forming a biomass-rich cover with mature soils where plant-dominated ecosystems later evolved. Understanding how life diversified and adapted to non-aquatic conditions from the actualistic and paleontological perspective is critical to understanding the impact of life on the Earth's systems over thousands of millions of years.

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Productivity-diversity relationships from chemolithoautotrophically based sulfidic karst systems

Cited by 74 publications

References 69 publications

Denitrification by sulfur-oxidizing bacteria in a eutrophic lake

Denitrification by sulfur-oxidizing bacteria in a eutrophic lake

Linking phylogenetic and functional diversity to nutrient spiraling in microbial mats from Lower Kane Cave (USA)

Early life on land and the first terrestrial ecosystems

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