larger proportion of arabinose in the monosaccharide composition of non-forest soil
than that of herbaceous plant materials.
In comparison to 4 woody plant materials except for a fallen trunk of Maries fir
(Fig. 6.2), forest soil and forest-derived arable soil contain a significantly much
larger proportion of mannose and fucose, and a significantly much smaller proportion of NEH-glucose (Fig. 6.3). Proportion of EH-glucose (average (av); 30.8%) and
rhamnose (av; 14.3%) of soil is significantly larger than EH-glucose (av; 5.2%) and
rhamnose (av; 2.5%) of woody plant materials at p ¼ 0.065 and p ¼ 0.10, respectively. Other sugars are not significantly different between soil and plant materials.
Mannose of needles of coniferous white-pine in Podzol soil was decomposed by
much larger rate (51%) than arabinose (26%) and xylose (37%) by 1200 days
incubation experiment (Sowden and Ivarson 1962). This suggests that in comparison
to pentose, mannose of coniferous litter may not be particularly recalcitrant in soil.
Accordingly, the monosaccharide composition suggests that EH-glucose, mannose,
fucose, and rhamnose can be synthesized by microorganism in forest soil and forestderived arable soil.
Forest soil showed a larger ratio of GM/AX and EH-glucose/NEH-glucose than
plant materials except for the fallen trunk of the coniferous tree
(Fig. 6.4 vs. Table 6.1, and Fig. 6.5 vs. Table 6.1, respectively).
In summary, comparison of the monosaccharide composition between soils and
plant materials suggests that EH-glucose, mannose, fucose, and rhamnose might be
synthesized by microbial communities in both forest and non-forest soils. Microbial
synthesis of galactose is suggested only in non-forest soil. The comparison procedure cannot confirm in principle whether any sugar cannot be synthesized by soil
microbial community.
6.3.2 Identification of Neutral Saccharides Synthesized
in Soil by Tracer Techniques
Studies in which soil is incubated with
14 C- and
13 C- labeled compounds such as
glucose have shown that the soil microbial community can synthesize all common
soil saccharides. However, soil microbes are unable to synthesize arabinose and
xylose in comparable amounts to galactose, glucose, and mannose (Cheshire et al.
1969, 1973, 1978; Oades and Wagner 1971; Murayama 1988; Derrien et al. 2007:
Basler et al. 2015).
The composition of neutral monosaccharides synthesized in soil under the same
incubation conditions differ among soils. Figure 6.6 shows the transformation of
13 C
from
13 C-labeled glucose into sugars after 56 days of incubation in the dark at 28
C
(Murayama 1988). The relative proportion of arabinose and xylose is smaller than
those of galactose, EH-glucose, mannose, fucose, and rhamnose across three soils.
This is consistent with the results of many other studies using labeled substrates.
However, differences in soil properties can cause some differences. The large
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S. Murayama and Y. Sugiura
than that of herbaceous plant materials.
In comparison to 4 woody plant materials except for a fallen trunk of Maries fir
(Fig. 6.2), forest soil and forest-derived arable soil contain a significantly much
larger proportion of mannose and fucose, and a significantly much smaller proportion of NEH-glucose (Fig. 6.3). Proportion of EH-glucose (average (av); 30.8%) and
rhamnose (av; 14.3%) of soil is significantly larger than EH-glucose (av; 5.2%) and
rhamnose (av; 2.5%) of woody plant materials at p ¼ 0.065 and p ¼ 0.10, respectively. Other sugars are not significantly different between soil and plant materials.
Mannose of needles of coniferous white-pine in Podzol soil was decomposed by
much larger rate (51%) than arabinose (26%) and xylose (37%) by 1200 days
incubation experiment (Sowden and Ivarson 1962). This suggests that in comparison
to pentose, mannose of coniferous litter may not be particularly recalcitrant in soil.
Accordingly, the monosaccharide composition suggests that EH-glucose, mannose,
fucose, and rhamnose can be synthesized by microorganism in forest soil and forestderived arable soil.
Forest soil showed a larger ratio of GM/AX and EH-glucose/NEH-glucose than
plant materials except for the fallen trunk of the coniferous tree
(Fig. 6.4 vs. Table 6.1, and Fig. 6.5 vs. Table 6.1, respectively).
In summary, comparison of the monosaccharide composition between soils and
plant materials suggests that EH-glucose, mannose, fucose, and rhamnose might be
synthesized by microbial communities in both forest and non-forest soils. Microbial
synthesis of galactose is suggested only in non-forest soil. The comparison procedure cannot confirm in principle whether any sugar cannot be synthesized by soil
microbial community.
6.3.2 Identification of Neutral Saccharides Synthesized
in Soil by Tracer Techniques
Studies in which soil is incubated with
14 C- and
13 C- labeled compounds such as
glucose have shown that the soil microbial community can synthesize all common
soil saccharides. However, soil microbes are unable to synthesize arabinose and
xylose in comparable amounts to galactose, glucose, and mannose (Cheshire et al.
1969, 1973, 1978; Oades and Wagner 1971; Murayama 1988; Derrien et al. 2007:
Basler et al. 2015).
The composition of neutral monosaccharides synthesized in soil under the same
incubation conditions differ among soils. Figure 6.6 shows the transformation of
13 C
from
13 C-labeled glucose into sugars after 56 days of incubation in the dark at 28
C
(Murayama 1988). The relative proportion of arabinose and xylose is smaller than
those of galactose, EH-glucose, mannose, fucose, and rhamnose across three soils.
This is consistent with the results of many other studies using labeled substrates.
However, differences in soil properties can cause some differences. The large
104
S. Murayama and Y. Sugiura