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Light structures phototroph, bacterial and fungal communities at the soil surface.

Davies LO, Schäfer H, Marshall S, Bramke I, Oliver RG, Bending GD - PLoS ONE (2013)

Bottom Line: Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus.The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes.However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, United Kingdom. l.o.davies@warwick.ac.uk

ABSTRACT
The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0-3 mm) and bulk soil (3-12 mm) using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.

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Chlorophyll a development in Gartenacker soil.Chlorophyll a in the surface (▴) and bulk (▾) of pasture soil after incubation under light (open symbols) or dark (closed symbols) conditions. Errors bars are ±1 standard error.
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pone-0069048-g001: Chlorophyll a development in Gartenacker soil.Chlorophyll a in the surface (▴) and bulk (▾) of pasture soil after incubation under light (open symbols) or dark (closed symbols) conditions. Errors bars are ±1 standard error.

Mentions: MPN assessment of algal abundance estimated a >60-fold greater algal population at the soil surface incubated under light compared to dark conditions for 80 days (p≤0.01) (Table 1). In addition, light (p≤0.001) and depth (p≤0.001) had a significant effect on chlorophyll a (Figure 1). Chlorophyll a was significantly higher at the soil surface under light at day 20, 40 and 80 (p≤0.001). Chlorophyll a was not detected in bulk soil under light or under dark conditions (Figure 1).


Light structures phototroph, bacterial and fungal communities at the soil surface.

Davies LO, Schäfer H, Marshall S, Bramke I, Oliver RG, Bending GD - PLoS ONE (2013)

Chlorophyll a development in Gartenacker soil.Chlorophyll a in the surface (▴) and bulk (▾) of pasture soil after incubation under light (open symbols) or dark (closed symbols) conditions. Errors bars are ±1 standard error.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3716809&req=5

pone-0069048-g001: Chlorophyll a development in Gartenacker soil.Chlorophyll a in the surface (▴) and bulk (▾) of pasture soil after incubation under light (open symbols) or dark (closed symbols) conditions. Errors bars are ±1 standard error.
Mentions: MPN assessment of algal abundance estimated a >60-fold greater algal population at the soil surface incubated under light compared to dark conditions for 80 days (p≤0.01) (Table 1). In addition, light (p≤0.001) and depth (p≤0.001) had a significant effect on chlorophyll a (Figure 1). Chlorophyll a was significantly higher at the soil surface under light at day 20, 40 and 80 (p≤0.001). Chlorophyll a was not detected in bulk soil under light or under dark conditions (Figure 1).

Bottom Line: Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus.The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes.However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, United Kingdom. l.o.davies@warwick.ac.uk

ABSTRACT
The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0-3 mm) and bulk soil (3-12 mm) using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.

Show MeSH
Related in: MedlinePlus