Abstract
In order to study controls on metabolic processes in soils, we determined the dynamics of 13CO2 production from two position-specific 13C-labeled pyruvate isotopologues in the presence and absence of glucose, succinate, pine, and legume leaf litter, and under anaerobic conditions. We also compared 13CO2 production in soils along a semiarid substrate age gradient in Arizona. We observed that the C from the carboxyl group (C1) of pyruvate was lost as CO2 much faster than its other C atoms (C2,3). Addition of glucose, pine and legume leaf litter reduced the ratio between 13CO2 production from 1-13C pyruvate and 2,3-13C pyruvate (C1/C2,3 ratio), whereas anaerobic conditions increased this ratio. Young volcanic soils exhibited a lower C1/C2,3 ratio than older volcanic soils. We interpret a low C1/C2,3 ratio as an indication of increased Krebs cycle activity in response to carbon inputs, while the higher ratio implies a reduced Krebs cycle activity in response to anaerobic conditions. Succinate, a gluconeogenic substrate, reduced 13CO2 production from pyruvate to near zero, likely reflecting increased carbohydrate biosynthesis from Krebs cycle intermediates. The difference in 13CO2 production rate from pyruvate isotopologues disappeared 4-5 days after pyruvate addition, indicating that C positions were scrambled by ongoing soil microbial transformations. This work demonstrates that metabolic tracers such as pyruvate can be used to determine qualitative aspects of C flux patterns through metabolic pathways of soil microbial communities. Understanding the controls over metabolic processes in soil may improve our understanding of soil C cycling processes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 126-132 |
| Number of pages | 7 |
| Journal | Soil Biology and Biochemistry |
| Volume | 43 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2011 |
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Keywords
- C and N availability
- C metabolism
- Carbon
- Soil microbial biomass
- Stable isotopes
ASJC Scopus subject areas
- Soil Science
- Microbiology
Cite this
Probing carbon flux patterns through soil microbial metabolic networks using parallel position-specific tracer labeling. / Dijkstra, Paul; Blankinship, Joseph C.; Selmants, Paul C.; Hart, Stephen C.; Koch, George W; Schwartz, Egbert; Hungate, Bruce A.
In: Soil Biology and Biochemistry, Vol. 43, No. 1, 01.2011, p. 126-132.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Probing carbon flux patterns through soil microbial metabolic networks using parallel position-specific tracer labeling
AU - Dijkstra, Paul
AU - Blankinship, Joseph C.
AU - Selmants, Paul C.
AU - Hart, Stephen C.
AU - Koch, George W
AU - Schwartz, Egbert
AU - Hungate, Bruce A
PY - 2011/1
Y1 - 2011/1
N2 - In order to study controls on metabolic processes in soils, we determined the dynamics of 13CO2 production from two position-specific 13C-labeled pyruvate isotopologues in the presence and absence of glucose, succinate, pine, and legume leaf litter, and under anaerobic conditions. We also compared 13CO2 production in soils along a semiarid substrate age gradient in Arizona. We observed that the C from the carboxyl group (C1) of pyruvate was lost as CO2 much faster than its other C atoms (C2,3). Addition of glucose, pine and legume leaf litter reduced the ratio between 13CO2 production from 1-13C pyruvate and 2,3-13C pyruvate (C1/C2,3 ratio), whereas anaerobic conditions increased this ratio. Young volcanic soils exhibited a lower C1/C2,3 ratio than older volcanic soils. We interpret a low C1/C2,3 ratio as an indication of increased Krebs cycle activity in response to carbon inputs, while the higher ratio implies a reduced Krebs cycle activity in response to anaerobic conditions. Succinate, a gluconeogenic substrate, reduced 13CO2 production from pyruvate to near zero, likely reflecting increased carbohydrate biosynthesis from Krebs cycle intermediates. The difference in 13CO2 production rate from pyruvate isotopologues disappeared 4-5 days after pyruvate addition, indicating that C positions were scrambled by ongoing soil microbial transformations. This work demonstrates that metabolic tracers such as pyruvate can be used to determine qualitative aspects of C flux patterns through metabolic pathways of soil microbial communities. Understanding the controls over metabolic processes in soil may improve our understanding of soil C cycling processes.
AB - In order to study controls on metabolic processes in soils, we determined the dynamics of 13CO2 production from two position-specific 13C-labeled pyruvate isotopologues in the presence and absence of glucose, succinate, pine, and legume leaf litter, and under anaerobic conditions. We also compared 13CO2 production in soils along a semiarid substrate age gradient in Arizona. We observed that the C from the carboxyl group (C1) of pyruvate was lost as CO2 much faster than its other C atoms (C2,3). Addition of glucose, pine and legume leaf litter reduced the ratio between 13CO2 production from 1-13C pyruvate and 2,3-13C pyruvate (C1/C2,3 ratio), whereas anaerobic conditions increased this ratio. Young volcanic soils exhibited a lower C1/C2,3 ratio than older volcanic soils. We interpret a low C1/C2,3 ratio as an indication of increased Krebs cycle activity in response to carbon inputs, while the higher ratio implies a reduced Krebs cycle activity in response to anaerobic conditions. Succinate, a gluconeogenic substrate, reduced 13CO2 production from pyruvate to near zero, likely reflecting increased carbohydrate biosynthesis from Krebs cycle intermediates. The difference in 13CO2 production rate from pyruvate isotopologues disappeared 4-5 days after pyruvate addition, indicating that C positions were scrambled by ongoing soil microbial transformations. This work demonstrates that metabolic tracers such as pyruvate can be used to determine qualitative aspects of C flux patterns through metabolic pathways of soil microbial communities. Understanding the controls over metabolic processes in soil may improve our understanding of soil C cycling processes.
KW - C and N availability
KW - C metabolism
KW - Carbon
KW - Soil microbial biomass
KW - Stable isotopes
UR - http://www.scopus.com/inward/record.url?scp=78449235830&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78449235830&partnerID=8YFLogxK
U2 - 10.1016/j.soilbio.2010.09.022
DO - 10.1016/j.soilbio.2010.09.022
M3 - Article
VL - 43
SP - 126
EP - 132
JO - Soil Biology and Biochemistry
JF - Soil Biology and Biochemistry
SN - 0038-0717
IS - 1
ER -