| Autor: |
Mendonca CM; Department of Biological and Environmental Engineering, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853, United States.; Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208, United States., Zhang L; Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois 60637, United States., Waldbauer JR; Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois 60637, United States., Aristilde L; Department of Biological and Environmental Engineering, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853, United States.; Department of Civil and Environmental Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208, United States. |
| Abstrakt: |
Microbial organic matter turnover is an important contributor to the terrestrial carbon dioxide (CO 2 ) budget. Partitioning of organic carbons into biomass relative to CO 2 efflux, termed carbon-use efficiency (CUE), is widely used to characterize organic carbon cycling by soil microorganisms. Recent studies challenge proposals of CUE dependence on the oxidation state of the substrate carbon and implicate instead metabolic strategies. Still unknown are the metabolic mechanisms underlying variability in CUE. We performed a multiomics investigation of these mechanisms in Pseudomonas putida , a versatile soil bacterium of the Gammaproteobacteria, processing a mixture of plant matter derivatives. Our 13 C-metabolomics data captured substrate carbons into different metabolic pathways: cellulose-derived sugar carbons in glycolytic and pentose-phosphate pathways; lignin-related aromatic carbons in the tricarboxylic acid cycle. Subsequent 13 C-metabolic flux analysis revealed a 3-fold lower investment of sugar carbons in CO 2 efflux compared to aromatic carbons, in agreement with reported substrate-dependent CUE. Proteomics analysis revealed enzyme-level regulation only for substrate uptake and initial catabolism, which dictated downstream fluxes through CO 2 -producing versus biomass-synthesizing reactions. Metabolic partitioning as shown here explained the substrate-dependent CUE calculated from reported metabolic flux analyses of other bacteria, further supporting a metabolism-guided perspective for predicting the microbial conversion of accessible organic matter to CO 2 efflux. |
