chemists, isotope chemists, nuclear physician, materials engineers, civil engineers,
and biotechnologists.
Chapter 1 provides a definition of sclerotia grains found in soils and differentiates
them from sclerotia propagules. It also provides a review of the melanized fungal
sclerotia produced by Cenococcum geophilum and related species. In addition, how
study of C. geophilum sclerotia has contributed to the field of earth science is
introduced.
Chapter 2 details molecular methods used to identify the fungi responsible for the
formation of sclerotia in soils and suggests that using culture-based methods may not
work to identify the fungus of origin because sclerotia persist in forest soils for a long
time, and the hyphae cell they contain may be too degraded for culture or DNA
extraction.
Chapter 3 describes the relationships between soil mesofauna, ECM fungi, and
sclerotia in forest soils by comparing fungal species extracted from soil mesofauna
and sclerotia and the ECM fungal community profiles in soil. Fungivory of Acari
and/or Collembola of sclerotia-forming ECM fungi is suggested as a key biological
process regulating sclerotia formation in forest soils.
Chapter 4 describes recent research on the diversity of microbial communities in
sclerotia grains and evaluates the potential for sclerotia grains to act as bacterial
carriers.
Chapter 5 details the physical and chemical characteristics of sclerotium grain
collected from a buried A horizon from a Japanese Andosol, using various instrumental techniques, i.e., C-NMR, FT-IR, Al-NMR, XRD, ICP-OES, ICP-MS.
Chapter 6 provides an overview of the origins of soil polysaccharide, and the
monosaccharide composition of various soils under different land use types. ECM
fungal sclerotia are discussed as sources of polysaccharides in forest soils.
Chapter 7 reports the results of accelerator mass spectrometry
14 C dating of
sclerotia grains, humic acid, and humin fractions from three different Andosol
profiles in Japan.
14 C dating allows us to determine the age of formation of
individual grains. These dates are more likely to indicate the beginning of soil
formation than the
14 C age of the humic acids.
Chapter 8 reports the micromorphological features of the interiors of sclerotia
grains examined by scanning electron microscopy and transmission electron microscopy combined with energy-dispersive X-ray and microcomputed tomography
analyses.
Chapters 9–11 compile comparative studies of geographical distribution and
properties of sclerotia grains in forest soils from Japan, Germany, and Mongolia.
A clear contrast in metal enrichment was shown between sclerotia grains in low-pH
forest soils and high-pH forest soils. Melanized sclerotia grains formed by ECM
fungi may be widely distributed in forest soil around the globe. Chapter 12 provides
concluding remarks: Investigating melanic sclerotia grains that bridge microbial and
pedogenic processes may clarify the biological intent of sclerotia formation and
autonomous homeostasis of soil ecosystem. Sclerotia grains, a mesoscale component
in soil, may hold the key to understanding novel aspects of soil ecological systems.
viii
Preface
and biotechnologists.
Chapter 1 provides a definition of sclerotia grains found in soils and differentiates
them from sclerotia propagules. It also provides a review of the melanized fungal
sclerotia produced by Cenococcum geophilum and related species. In addition, how
study of C. geophilum sclerotia has contributed to the field of earth science is
introduced.
Chapter 2 details molecular methods used to identify the fungi responsible for the
formation of sclerotia in soils and suggests that using culture-based methods may not
work to identify the fungus of origin because sclerotia persist in forest soils for a long
time, and the hyphae cell they contain may be too degraded for culture or DNA
extraction.
Chapter 3 describes the relationships between soil mesofauna, ECM fungi, and
sclerotia in forest soils by comparing fungal species extracted from soil mesofauna
and sclerotia and the ECM fungal community profiles in soil. Fungivory of Acari
and/or Collembola of sclerotia-forming ECM fungi is suggested as a key biological
process regulating sclerotia formation in forest soils.
Chapter 4 describes recent research on the diversity of microbial communities in
sclerotia grains and evaluates the potential for sclerotia grains to act as bacterial
carriers.
Chapter 5 details the physical and chemical characteristics of sclerotium grain
collected from a buried A horizon from a Japanese Andosol, using various instrumental techniques, i.e., C-NMR, FT-IR, Al-NMR, XRD, ICP-OES, ICP-MS.
Chapter 6 provides an overview of the origins of soil polysaccharide, and the
monosaccharide composition of various soils under different land use types. ECM
fungal sclerotia are discussed as sources of polysaccharides in forest soils.
Chapter 7 reports the results of accelerator mass spectrometry
14 C dating of
sclerotia grains, humic acid, and humin fractions from three different Andosol
profiles in Japan.
14 C dating allows us to determine the age of formation of
individual grains. These dates are more likely to indicate the beginning of soil
formation than the
14 C age of the humic acids.
Chapter 8 reports the micromorphological features of the interiors of sclerotia
grains examined by scanning electron microscopy and transmission electron microscopy combined with energy-dispersive X-ray and microcomputed tomography
analyses.
Chapters 9–11 compile comparative studies of geographical distribution and
properties of sclerotia grains in forest soils from Japan, Germany, and Mongolia.
A clear contrast in metal enrichment was shown between sclerotia grains in low-pH
forest soils and high-pH forest soils. Melanized sclerotia grains formed by ECM
fungi may be widely distributed in forest soil around the globe. Chapter 12 provides
concluding remarks: Investigating melanic sclerotia grains that bridge microbial and
pedogenic processes may clarify the biological intent of sclerotia formation and
autonomous homeostasis of soil ecosystem. Sclerotia grains, a mesoscale component
in soil, may hold the key to understanding novel aspects of soil ecological systems.
viii
Preface