Details

Autor(en) / Beteiligte

• Rempfert, Kaitlin R.
• Bell, Sheryl L.
• Kasanke, Christopher P.
• Zhao, Qian
• Zhao, Xiaodong
• Lipton, Andrew S.
• Hofmockel, Kirsten S.

Titel

Biomolecular budget of persistent, microbial-derived soil organic carbon: The importance of underexplored pools

Ist Teil von

• The Science of the total environment, 2024-07, Vol.932 (2024), p.172916-172916, Article 172916

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2024

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The details of how soil microorganisms contribute to stable soil organic carbon pools are a pressing knowledge gap with direct implications for soil health and climate mitigation. It is now recognized that microbial necromass contributes substantially to the formation of stable soil carbon. However, the quantification of necromass in soils has largely been limited to model molecules such as aminosugar biomarkers. The abundance and chemical composition of other persistent microbial residues remain unresolved, particularly concerning how these pools may vary with microbial community structure, soil texture, and management practices. Here we use yearlong soil incubation experiments with an isotopic tracer to quantify the composition of persistent residues derived from microbial communities inhabiting sand or silt dominated soil with annual (corn) or perennial (switchgrass) monocultures. Persistent microbial residues were recovered in diverse soil biomolecular pools including metabolites, proteins, lipids, and mineral-associated organic matter (MAOM). The relative abundances of microbial contributions to necromass pools were consistent across cropping systems and soil textures. The greatest residue accumulation was not recovered in MAOM but in the light density fraction of soil debris that persisted after extraction by chemical fractionation using organic solvents. Necromass abundance was positively correlated with microbial biomass abundance and revealed a possible role of cell wall morphology in enhancing microbial carbon persistence; while gram-negative bacteria accounted for the greatest contribution to microbial-derived carbon by mass at one year, residues from gram-positive Actinobacteria and Firmicutes showed greater durability. Together these results offer a quantitative assessment of the relative importance of diverse molecular classes for generating durable soil carbon. Conceptual model for necromass formation and persistence in soils. Carbon (C) inputs from plants can be metabolized and assimilated or respired by microorganisms. Biomolecular components (lipids, proteins, metabolites, cell wall) of microbial biomass may persist as necromass after cell death through sorption to minerals to form mineral-associated organic matter (MAOM) or be recycled by the living microbial community. In this study, unextracted and complex residual unidentified debris (CRUD) representing Folch-extracted MAOM were both analyzed. [Display omitted] •Soil microbial residues are composed of diverse pools including metabolites.•Persistent residue accrual was correlated with microbial biomass abundance.•Microbial metabolites may be an important means of accumulating soil carbon.•Cell wall morphology may play a role in microbial-derived carbon durability.