Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

Carol Arnosti, Niko Finke, Ole Larsen, S. Ghobrial

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Complex substrates are degraded in anoxic sediments by the concerted activities of diverse
microbial communities. To explore the effects of substrate complexity on carbon transformations in permanently
cold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high molecular
weight carbohydrate-rich extracts of these cells (Spir-Ex and Iso-Ex)—were added to sediments collected
from Svalbard. The sediments were homogenized, incubated anaerobically in gas-tight bags at 0°C, and
enzyme activities, fermentation, and terminal respiration were monitored over a 1134 h time course. All
substrate additions yielded a fraction (8%–13%) of carbon that was metabolized to CO2 over the first 384 h
of incubation. The timecourse of VFA (volatile fatty acid) production and consumption, as well as the suite
of VFAs produced, was similar for all substrates. After this phase, pathways of carbon degradation diverged,
with an additional 43%, 32%, 33%, and 8% of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired to
CO2 over the next 750 h of incubation. Somewhat surprisingly, the soluble, carbohydrate-rich extracts did not
prove to be more labile substrates than the whole cells from which they were derived. Although Spirulina and
Iso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydrate
content), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbon
was respired, despite the initial burst of activity that it fueled, its soluble nature, and its relatively high (50%)
carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity to
react rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar to
observations made at much higher temperatures in temperate sediments. The extent of carbon remineralization
from these specific substrates, however, would not likely have been predicted on the basis of general substrate
characteristics.
OriginalsprogEngelsk
TidsskriftGeochimica et Cosmochimica Acta
Vol/bind69
Udgave nummer9
Sider (fra-til)2309-2320
Antal sider12
ISSN0016-7037
DOI
StatusUdgivet - 2005

Fingeraftryk

substrate
degradation
carbon
sediment
anoxic sediment
carbohydrate
incubation
remineralization
fermentation
microbial community
respiration
fatty acid
lipid
gas

Citer dette

Arnosti, Carol ; Finke, Niko ; Larsen, Ole ; Ghobrial, S. / Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates. I: Geochimica et Cosmochimica Acta. 2005 ; Bind 69, Nr. 9. s. 2309-2320.
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title = "Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates",
abstract = "Complex substrates are degraded in anoxic sediments by the concerted activities of diversemicrobial communities. To explore the effects of substrate complexity on carbon transformations in permanentlycold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high molecularweight carbohydrate-rich extracts of these cells (Spir-Ex and Iso-Ex)—were added to sediments collectedfrom Svalbard. The sediments were homogenized, incubated anaerobically in gas-tight bags at 0°C, andenzyme activities, fermentation, and terminal respiration were monitored over a 1134 h time course. Allsubstrate additions yielded a fraction (8{\%}–13{\%}) of carbon that was metabolized to CO2 over the first 384 hof incubation. The timecourse of VFA (volatile fatty acid) production and consumption, as well as the suiteof VFAs produced, was similar for all substrates. After this phase, pathways of carbon degradation diverged,with an additional 43{\%}, 32{\%}, 33{\%}, and 8{\%} of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired toCO2 over the next 750 h of incubation. Somewhat surprisingly, the soluble, carbohydrate-rich extracts did notprove to be more labile substrates than the whole cells from which they were derived. Although Spirulina andIso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydratecontent), nearly identical quantities of carbon were respired to CO2. In contrast, only 15{\%} of Spir-Ex carbonwas respired, despite the initial burst of activity that it fueled, its soluble nature, and its relatively high (50{\%})carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity toreact rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar toobservations made at much higher temperatures in temperate sediments. The extent of carbon remineralizationfrom these specific substrates, however, would not likely have been predicted on the basis of general substratecharacteristics.",
author = "Carol Arnosti and Niko Finke and Ole Larsen and S. Ghobrial",
year = "2005",
doi = "10.1016/j.gca.2004.11.011",
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Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates. / Arnosti, Carol; Finke, Niko; Larsen, Ole; Ghobrial, S.

I: Geochimica et Cosmochimica Acta, Bind 69, Nr. 9, 2005, s. 2309-2320.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

AU - Arnosti, Carol

AU - Finke, Niko

AU - Larsen, Ole

AU - Ghobrial, S.

PY - 2005

Y1 - 2005

N2 - Complex substrates are degraded in anoxic sediments by the concerted activities of diversemicrobial communities. To explore the effects of substrate complexity on carbon transformations in permanentlycold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high molecularweight carbohydrate-rich extracts of these cells (Spir-Ex and Iso-Ex)—were added to sediments collectedfrom Svalbard. The sediments were homogenized, incubated anaerobically in gas-tight bags at 0°C, andenzyme activities, fermentation, and terminal respiration were monitored over a 1134 h time course. Allsubstrate additions yielded a fraction (8%–13%) of carbon that was metabolized to CO2 over the first 384 hof incubation. The timecourse of VFA (volatile fatty acid) production and consumption, as well as the suiteof VFAs produced, was similar for all substrates. After this phase, pathways of carbon degradation diverged,with an additional 43%, 32%, 33%, and 8% of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired toCO2 over the next 750 h of incubation. Somewhat surprisingly, the soluble, carbohydrate-rich extracts did notprove to be more labile substrates than the whole cells from which they were derived. Although Spirulina andIso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydratecontent), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbonwas respired, despite the initial burst of activity that it fueled, its soluble nature, and its relatively high (50%)carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity toreact rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar toobservations made at much higher temperatures in temperate sediments. The extent of carbon remineralizationfrom these specific substrates, however, would not likely have been predicted on the basis of general substratecharacteristics.

AB - Complex substrates are degraded in anoxic sediments by the concerted activities of diversemicrobial communities. To explore the effects of substrate complexity on carbon transformations in permanentlycold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high molecularweight carbohydrate-rich extracts of these cells (Spir-Ex and Iso-Ex)—were added to sediments collectedfrom Svalbard. The sediments were homogenized, incubated anaerobically in gas-tight bags at 0°C, andenzyme activities, fermentation, and terminal respiration were monitored over a 1134 h time course. Allsubstrate additions yielded a fraction (8%–13%) of carbon that was metabolized to CO2 over the first 384 hof incubation. The timecourse of VFA (volatile fatty acid) production and consumption, as well as the suiteof VFAs produced, was similar for all substrates. After this phase, pathways of carbon degradation diverged,with an additional 43%, 32%, 33%, and 8% of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired toCO2 over the next 750 h of incubation. Somewhat surprisingly, the soluble, carbohydrate-rich extracts did notprove to be more labile substrates than the whole cells from which they were derived. Although Spirulina andIso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydratecontent), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbonwas respired, despite the initial burst of activity that it fueled, its soluble nature, and its relatively high (50%)carbohydrate content. The microbial community in these cold anoxic sediments clearly has the capacity toreact rapidly to carbon input; extent and timecourse of remineralization of added carbon is similar toobservations made at much higher temperatures in temperate sediments. The extent of carbon remineralizationfrom these specific substrates, however, would not likely have been predicted on the basis of general substratecharacteristics.

U2 - 10.1016/j.gca.2004.11.011

DO - 10.1016/j.gca.2004.11.011

M3 - Journal article

VL - 69

SP - 2309

EP - 2320

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

IS - 9

ER -