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- Dijkstra, Paul, et al.
(författare)
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On maintenance and metabolisms in soil microbial communities
- 2022
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 476:1-2, s. 385-396
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Tidskriftsartikel (refereegranskat)abstract
- Scope Biochemistry is an essential yet undervalued aspect of soil ecology, especially when analyzing soil C cycling. We assume, based on tradition, intuition or hope, that the complexity of biochemistry is confined to the microscopic world, and can be ignored when dealing with whole soil systems. This opinion paper draws attention to patterns caused by basic biochemical processes that permeate the world of ecosystem processes. From these patterns, we can estimate activities of the biochemical reactions of the central C metabolic network and gain insights into the ecophysiology of microbial biosynthesis, growth, and maintenance energy requirements: important components of Carbon Use Efficiency (CUE).Observations We show that glucose is processed via the Embden-Meyerhof-Parnas glycolysis in one soil, but via Pentose Phosphate or Entner-Doudoroff pathways in two other soils. However, notwithstanding this metabolic diversity, glucose use efficiency is high and thus substrate use for maintenance energy and overflow respiration is low in these soils. These results contradict current dogma, based on four decades of debate in soil ecology, that the maintenance energy demand in soil communities is a quantitative important, although variable, component of soil community energy metabolism.Conclusions We identify three main shortcomings in our current understanding of substrate use efficiency: 1) in numeric and conceptual models, we lack appreciation of the strategies that microbes employ to quickly reduce energy needs in response to starvation; 2) in order to understand variation in CUE, we need to improve our understanding of the processes of exudation (including all changes in allocation of C from the cell soluble to insoluble fraction and extracellular environment) and microbial turnover; and 3) whether tracer experiments can be used to measure the long-term substrate use efficiency of soil microbial communities depends critically on the ability and speed with which non-growing cells take up tracer substrates and metabolism activates and subsequently de-activates in response to starvation, as well as on how cellular activities scale to the community level. To move the field of soil ecology forward, future research must consider the details of microbial ecophysiology and develop new tools that enable direct measurement of microbial functioning in intact soils. We submit that 13C metabolic flux analysis is one of those new tools.
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| 2. |
- Wu, Weichao, et al.
(författare)
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In situ diversity of metabolism and carbon use efficiency among soil bacteria
- 2022
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 8:44
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Tidskriftsartikel (refereegranskat)abstract
- The central carbon (C) metabolic network harvests energy to power the cell and feed biosynthesis for growth. In pure cultures, bacteria use some but not all of the network’s major pathways, such as glycolysis and pentose phosphate and Entner-Doudoroff pathways. However, how these pathways are used in microorganisms in intact soil communities is unknown. Here, we analyzed the incorporation of 13C from glucose isotopomers into phospholipid fatty acids. We showed that groups of Gram-positive and Gram-negative bacteria in an intact agricultural soil used different pathways to metabolize glucose. They also differed in C use efficiency (CUE), the efficiency with which a substrate is used for biosynthesis. Our results provide experimental evidence for diversity among microbes in the organization of their central carbon metabolic network and CUE under in situ conditions. These results have important implications for our understanding of how community composition affects soil C cycling and organic matter formation.
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