TY - JOUR

T1 - Microbial cell-envelope fragments and the formation of soil organic matter

T2 - A case study from a glacier forefield

AU - Schurig, Christian

AU - Smittenberg, Rienk H.

AU - Berger, Juergen

AU - Kraft, Fabio

AU - Woche, Susanne K.

AU - Goebel, Marc O.

AU - Heipieper, Hermann J.

AU - Miltner, Anja

AU - Kaestner, Matthias

N1 - Funding Information: Acknowledgments We gratefully acknowledge the financial support for this study from the Helmholtz Centre for Environmental Research-UFZ Leipzig and the German Research Council (project DynaCARB, MI 598/2-2; within the framework of the SPP 1315: Biogeochemical Interfaces in Soil). C.S was funded by a grant of the European Union (FP7 Contract No. 213161 ModelPROBE). R.H.S provided access to the field sites and was funded by the Competence Center Environment and Sustainability of the ETH domain through the project BigLink. We are also very grateful to Peter Fittkau for EDX analyses of some scanning electron micoscopy samples and to Andreas Kappler for providing the contacts to Peter Fittkau and the MPI. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2013/5

Y1 - 2013/5

N2 - Genesis of soil organic matter (SOM) during pedogenesis is still a matter of controversy in soil science. Recently, it was hypothesized that microbial cell-envelope fragments contribute significantly to SOM formation. We tested the relevance of this process during pedogenesis by evaluating the development of SOM along a chronosequence of a glacier forefield (Damma glacier). Samples of increasing soil age collected along the forefield were analyzed for C and N contents, phospholipid and total fatty acids (PLFA and tFA), water contact angle, micro-hydrophobicity and surface coverage by microbial cell-envelope residues. The surface coverage was visualized and quantified by analysis of representative, equally-scaled scanning electron micrographs (SEM). Increasing SOM contents were accompanied by increasing coverage and overall abundance of microbial cell-envelope fragments as evaluated on the basis of scanning electron microscopy; this is also reflected in the amounts of tFA and PLFA, the trend of C/N ratios, and the increasing hydrophobicity and water contact angles of the soil samples. Using SEM and the image analysis approach, we can provide a process-based description of the development of SOM in the newly developing ecosystem of the glacier forefield. The majority of small-sized SOM visible with scanning electron microscopy appears to consist of bacterial cell envelope fragments that remain stable after cell death, such that their shape does not change with soil age. Our results show the importance of microbial processing of SOM, and highlight the existence of microbial necromass as a significant part of the fine-particulate SOM even in later stages of soil development.

AB - Genesis of soil organic matter (SOM) during pedogenesis is still a matter of controversy in soil science. Recently, it was hypothesized that microbial cell-envelope fragments contribute significantly to SOM formation. We tested the relevance of this process during pedogenesis by evaluating the development of SOM along a chronosequence of a glacier forefield (Damma glacier). Samples of increasing soil age collected along the forefield were analyzed for C and N contents, phospholipid and total fatty acids (PLFA and tFA), water contact angle, micro-hydrophobicity and surface coverage by microbial cell-envelope residues. The surface coverage was visualized and quantified by analysis of representative, equally-scaled scanning electron micrographs (SEM). Increasing SOM contents were accompanied by increasing coverage and overall abundance of microbial cell-envelope fragments as evaluated on the basis of scanning electron microscopy; this is also reflected in the amounts of tFA and PLFA, the trend of C/N ratios, and the increasing hydrophobicity and water contact angles of the soil samples. Using SEM and the image analysis approach, we can provide a process-based description of the development of SOM in the newly developing ecosystem of the glacier forefield. The majority of small-sized SOM visible with scanning electron microscopy appears to consist of bacterial cell envelope fragments that remain stable after cell death, such that their shape does not change with soil age. Our results show the importance of microbial processing of SOM, and highlight the existence of microbial necromass as a significant part of the fine-particulate SOM even in later stages of soil development.

KW - C/N ratio

KW - Chronosequence

KW - Contact angle

KW - FA

KW - Glacier forefield

KW - Hydrophobicity

KW - Microbial cell-envelope residues

KW - PLFA

KW - SOM formation

UR - http://www.scopus.com/inward/record.url?scp=84876281182&partnerID=8YFLogxK

U2 - 10.1007/s10533-012-9791-3

DO - 10.1007/s10533-012-9791-3

M3 - Article

AN - SCOPUS:84876281182

VL - 113

SP - 595

EP - 612

JO - BIOGEOCHEMISTRY

JF - BIOGEOCHEMISTRY

SN - 0168-2563

IS - 1-3

ER -