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Belowground Response to Drought in a Tropical Forest Soil. I. Changes in Microbial Functional Potential and Metabolism.

Bouskill NJ, Wood TE, Baran R, Ye Z, Bowen BP, Lim H, Zhou J, Nostrand JD, Nico P, Northen TR, Silver WL, Brodie EL - Front Microbiol (2016)

Bottom Line: This approach reduced soil moisture by 13% and water potential by 0.14 MPa (from -0.2 to -0.34).Previous results from this experiment have demonstrated that the diversity and composition of these soil microbial communities are sensitive to even small changes in soil water.Subsequently, a microbial population emerges with a greater capacity for extracellular enzyme production targeting macromolecular carbon.

View Article: PubMed Central - PubMed

Affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National Laboratory Berkeley, CA, USA.

ABSTRACT
Global climate models predict a future of increased severity of drought in many tropical forests. Soil microbes are central to the balance of these systems as sources or sinks of atmospheric carbon (C), yet how they respond metabolically to drought is not well-understood. We simulated drought in the typically aseasonal Luquillo Experimental Forest, Puerto Rico, by intercepting precipitation falling through the forest canopy. This approach reduced soil moisture by 13% and water potential by 0.14 MPa (from -0.2 to -0.34). Previous results from this experiment have demonstrated that the diversity and composition of these soil microbial communities are sensitive to even small changes in soil water. Here, we show prolonged drought significantly alters the functional potential of the community and provokes a clear osmotic stress response, including the production of compatible solutes that increase intracellular C demand. Subsequently, a microbial population emerges with a greater capacity for extracellular enzyme production targeting macromolecular carbon. Significantly, some of these drought-induced functional shifts in the soil microbiota are attenuated by prior exposure to a short-term drought suggesting that acclimation may occur despite a lack of longer-term drought history.

No MeSH data available.


Related in: MedlinePlus

Abundance of metabolites positively identified as compatible solutes following 10 months of throughfall exclusion. The bar plots represent the mean (± standard deviation) of activities across the treatments (n = 5). The symbols next to the bars denote significantly different between one of the treatments and control (red star) soils or significant different between treatment soils (blue star).
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Figure 4: Abundance of metabolites positively identified as compatible solutes following 10 months of throughfall exclusion. The bar plots represent the mean (± standard deviation) of activities across the treatments (n = 5). The symbols next to the bars denote significantly different between one of the treatments and control (red star) soils or significant different between treatment soils (blue star).

Mentions: Using an untargeted LC–MS/MS approach (environmental metabolomics) we identified a number of compatible solutes that are either synthesized or accumulated by microbial cells under osmotic stress. Both trehalose and ectoine were detected solely in soils undergoing drought (Figure 4). Trehalose abundance was also significantly elevated in the de novo excluded soils relative to the pre-excluded (p < 0.05). Glycine betaine was significantly higher in the de novo excluded soils relative to either the control or pre-excluded soils (p < 0.001). Glycine betaine was also in higher abundance in the pre-excluded soils relative to the controls. Several amino acids (e.g., alanine, glutamate, proline), that have been shown to accumulate during osmotic stress, were in higher relative abundance in the de novo soils than either the pre-excluded or the control soils (Figure 4). Mannosylglycerate was significantly higher in the de novo soils relative to the control and pre-excluded (p < 0.001). Finally, carnitine was significantly higher in both of the treatment soils relative to the control (p < 0.05).


Belowground Response to Drought in a Tropical Forest Soil. I. Changes in Microbial Functional Potential and Metabolism.

Bouskill NJ, Wood TE, Baran R, Ye Z, Bowen BP, Lim H, Zhou J, Nostrand JD, Nico P, Northen TR, Silver WL, Brodie EL - Front Microbiol (2016)

Abundance of metabolites positively identified as compatible solutes following 10 months of throughfall exclusion. The bar plots represent the mean (± standard deviation) of activities across the treatments (n = 5). The symbols next to the bars denote significantly different between one of the treatments and control (red star) soils or significant different between treatment soils (blue star).
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Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837414&req=5

Figure 4: Abundance of metabolites positively identified as compatible solutes following 10 months of throughfall exclusion. The bar plots represent the mean (± standard deviation) of activities across the treatments (n = 5). The symbols next to the bars denote significantly different between one of the treatments and control (red star) soils or significant different between treatment soils (blue star).
Mentions: Using an untargeted LC–MS/MS approach (environmental metabolomics) we identified a number of compatible solutes that are either synthesized or accumulated by microbial cells under osmotic stress. Both trehalose and ectoine were detected solely in soils undergoing drought (Figure 4). Trehalose abundance was also significantly elevated in the de novo excluded soils relative to the pre-excluded (p < 0.05). Glycine betaine was significantly higher in the de novo excluded soils relative to either the control or pre-excluded soils (p < 0.001). Glycine betaine was also in higher abundance in the pre-excluded soils relative to the controls. Several amino acids (e.g., alanine, glutamate, proline), that have been shown to accumulate during osmotic stress, were in higher relative abundance in the de novo soils than either the pre-excluded or the control soils (Figure 4). Mannosylglycerate was significantly higher in the de novo soils relative to the control and pre-excluded (p < 0.001). Finally, carnitine was significantly higher in both of the treatment soils relative to the control (p < 0.05).

Bottom Line: This approach reduced soil moisture by 13% and water potential by 0.14 MPa (from -0.2 to -0.34).Previous results from this experiment have demonstrated that the diversity and composition of these soil microbial communities are sensitive to even small changes in soil water.Subsequently, a microbial population emerges with a greater capacity for extracellular enzyme production targeting macromolecular carbon.

View Article: PubMed Central - PubMed

Affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National Laboratory Berkeley, CA, USA.

ABSTRACT
Global climate models predict a future of increased severity of drought in many tropical forests. Soil microbes are central to the balance of these systems as sources or sinks of atmospheric carbon (C), yet how they respond metabolically to drought is not well-understood. We simulated drought in the typically aseasonal Luquillo Experimental Forest, Puerto Rico, by intercepting precipitation falling through the forest canopy. This approach reduced soil moisture by 13% and water potential by 0.14 MPa (from -0.2 to -0.34). Previous results from this experiment have demonstrated that the diversity and composition of these soil microbial communities are sensitive to even small changes in soil water. Here, we show prolonged drought significantly alters the functional potential of the community and provokes a clear osmotic stress response, including the production of compatible solutes that increase intracellular C demand. Subsequently, a microbial population emerges with a greater capacity for extracellular enzyme production targeting macromolecular carbon. Significantly, some of these drought-induced functional shifts in the soil microbiota are attenuated by prior exposure to a short-term drought suggesting that acclimation may occur despite a lack of longer-term drought history.

No MeSH data available.


Related in: MedlinePlus