Microbial growth and carbon use efficiency in the rhizosphere and root-free soil.
Plant-microbial interactions alter C and N balance in the rhizosphere and affect the microbial carbon use efficiency (CUE)-the fundamental characteristic of microbial metabolism. Estimation of CUE in microbial hotspots with high dynamics of activity and changes of microbial physiological state from dormancy to activity is a challenge in soil microbiology. We analyzed respiratory activity, microbial DNA content and CUE by manipulation the C and nutrients availability in the soil under Beta vulgaris. All measurements were done in root-free and rhizosphere soil under steady-state conditions and during microbial growth induced by addition of glucose. Microorganisms in the rhizosphere and root-free soil differed in their CUE dynamics due to varying time delays between respiration burst and DNA increase. Constant CUE in an exponentially-growing microbial community in rhizosphere demonstrated the balanced growth. In contrast, the CUE in the root-free soil increased more than three times at the end of exponential growth and was 1.5 times higher than in the rhizosphere. Plants alter the dynamics of microbial CUE by balancing the catabolic and anabolic processes, which were decoupled in the root-free soil. The effects of N and C availability on CUE in rhizosphere and root-free soil are discussed.
Soil Science of Temperate Ecosystems, Büsgen-Institute, University of Göttingen, Göttingen, Germany; Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino, Russia; Agricultural Soil Science, Büsgen-Institute, University of Göttingen, Göttingen, Germany.
Evgenia
E
Blagodatskaya
Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino, Russia; Institute for Plant Production and Agroecology in the Tropics and Subtropics, University of Hohenheim, Stuttgart, Germany.
Sergey
S
Blagodatsky
Thünen-Institute of Climate-Smart Agriculture (vTI), Braunschweig, Germany.
Traute-Heidi
TH
Anderson
Soil Science of Temperate Ecosystems, Büsgen-Institute, University of Göttingen, Göttingen, Germany; Agricultural Soil Science, Büsgen-Institute, University of Göttingen, Göttingen, Germany.
Yakov
Y
Kuzyakov
D027461:Beta vulgaris / Q000378:metabolism; D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry; D004269:DNA, Bacterial / Q000235:genetics; D017753:Ecosystem; D005947:Glucose / Q000737:chemistry; D056265:Microbial Interactions; D009584:Nitrogen / Q000737:chemistry; D018517:Plant Roots / Q000378:metabolism*; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013997:Time Factors
D004269:DNA, Bacterial; D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon; D005947:Glucose; D009584:Nitrogen