Beyond Growth: The Significance of Non-Growth Anabolism for Microbial Carbon-Use Efficiency in the Light of Soil Carbon Stabilisation

57 Pages Posted: 24 Oct 2023 Last revised: 8 Feb 2024

See all articles by Tobias Bölscher

Tobias Bölscher

French National Institute for Agriculture, Food and Environment (INRAE)

Cordula Vogel

Dresden University of Technology

Folasade K. Olagoke

Dresden University of Technology

Katharina H.E. Meurer

Swedish University of Agricultural Sciences (SLU)

Anke M. Herrmann

Swedish University of Agricultural Sciences (SLU)

Tino Colombi

Swedish University of Agricultural Sciences (SLU)

Melanie Brunn

University of Koblenz-Landau

Luiz A. Domeignoz-Horta

University of Zurich

Abstract

Microbial carbon-use efficiency (CUE) in soils captures carbon (C) partitioning between anabolic biosynthesis of microbial metabolites and catabolic C emissions (i.e. respiratory C waste). The use of C for biosynthesis provides a potential for the accumulation of microbial metabolic residues in soil. Recognised as a crucial control in C cycling, microbial CUE is implemented in the majority of soil C models. Due to the models’ high sensitivity to CUE, reliable soil C projections demand accurate CUE quantifications. Current measurements of CUE neglect microbial non-growth metabolites, such as extracellular polymeric substances (EPS) or exoenzymes, although they remain in soil and could be quantitatively important. Here, we highlight that disregarding non-growth anabolism can lead to severe underestimations of CUE. Based on two case studies, we demonstrate that neglecting exoenzyme and EPS production underestimates CUE by more than 100% and up to 30%, respectively. By incorporating these case-specific values in model simulations, we observed that the model projects up to 34% larger SOC stocks over a period of 64 years when non-growth metabolites are considered for estimating CUE, highlighting the crucial importance of accurate CUE quantification. Our considerations outlined here challenge the current ways how CUE is measured and we suggest improvements concerning the quantification of non-growth metabolites. Research efforts should focus on (i) advancing CUE estimations by capturing the multitude of microbial C uses, (ii) improving techniques to quantify non-growth metabolic products in soil, and (iii) providing an understanding of dynamic metabolic C uses under different environmental conditions and over time. In the light of current discussion on soil C stabilisation mechanisms, we call for efforts to open the ‘black box’ of microbial physiology in soil and to incorporate all quantitative important C uses in CUE measurements.

Keywords: microbial growth efficiency, substrate-use efficiency, microbial physiology, non-growth metabolism, microbial exudates, soil carbon models

Suggested Citation

Bölscher, Tobias and Vogel, Cordula and Olagoke, Folasade K. and Meurer, Katharina H.E. and Herrmann, Anke M. and Colombi, Tino and Brunn, Melanie and Domeignoz-Horta, Luiz A., Beyond Growth: The Significance of Non-Growth Anabolism for Microbial Carbon-Use Efficiency in the Light of Soil Carbon Stabilisation. Available at SSRN: https://ssrn.com/abstract=4596729 or http://dx.doi.org/10.2139/ssrn.4596729

Tobias Bölscher (Contact Author)

French National Institute for Agriculture, Food and Environment (INRAE) ( email )

Versailles-Saclay
France

Cordula Vogel

Dresden University of Technology ( email )

Folasade K. Olagoke

Dresden University of Technology ( email )

Katharina H.E. Meurer

Swedish University of Agricultural Sciences (SLU) ( email )

Anke M. Herrmann

Swedish University of Agricultural Sciences (SLU) ( email )

S-901 83 Umea
Sweden

Tino Colombi

Swedish University of Agricultural Sciences (SLU) ( email )

Melanie Brunn

University of Koblenz-Landau ( email )

Luiz A. Domeignoz-Horta

University of Zurich ( email )

Rämistrasse 71
Zürich, CH-8006
Switzerland

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