Limits...
Litter Breakdown and Microbial Succession on Two Submerged Leaf Species in a Small Forested Stream.

Newman MM, Liles MR, Feminella JW - PLoS ONE (2015)

Bottom Line: PLFA revealed a significant time effect on microbial lipid profiles for both leaf species.Next-generation sequencing revealed temporal shifts in dominant taxa within the phylum Proteobacteria, whereas γ-Proteobacteria dominated pre-immersion and α- and β-Proteobacteria dominated after 1 month of instream incubation; the latter groups contain taxa that are predicted to be capable of using organic material to fuel further breakdown.Our results suggest that incubation time is more important than leaf species physicochemistry in influencing leaf litter microbial assemblage composition, and indicate the need for investigation into seasonal and temporal dynamics of leaf litter microbial assemblage succession.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Auburn University, Auburn, Alabama, United States of America.

ABSTRACT
Microbial succession during leaf breakdown was investigated in a small forested stream in west-central Georgia, USA, using multiple culture-independent techniques. Red maple (Acer rubrum) and water oak (Quercus nigra) leaf litter were incubated in situ for 128 days, and litter breakdown was quantified by ash-free dry mass (AFDM) method and microbial assemblage composition using phospholipid fatty acid analysis (PLFA), ribosomal intergenic spacer analysis (RISA), denaturing gradient gel electrophoresis (DGGE), and bar-coded next-generation sequencing of 16S rRNA gene amplicons. Leaf breakdown was faster for red maple than water oak. PLFA revealed a significant time effect on microbial lipid profiles for both leaf species. Microbial assemblages on maple contained a higher relative abundance of bacterial lipids than oak, and oak microbial assemblages contained higher relative abundance of fungal lipids than maple. RISA showed that incubation time was more important in structuring bacterial assemblages than leaf physicochemistry. DGGE profiles revealed high variability in bacterial assemblages over time, and sequencing of DGGE-resolved amplicons indicated several taxa present on degrading litter. Next-generation sequencing revealed temporal shifts in dominant taxa within the phylum Proteobacteria, whereas γ-Proteobacteria dominated pre-immersion and α- and β-Proteobacteria dominated after 1 month of instream incubation; the latter groups contain taxa that are predicted to be capable of using organic material to fuel further breakdown. Our results suggest that incubation time is more important than leaf species physicochemistry in influencing leaf litter microbial assemblage composition, and indicate the need for investigation into seasonal and temporal dynamics of leaf litter microbial assemblage succession.

No MeSH data available.


Mean (± 1SE) ash free dry mass (AFDM) remaining over time during breakdown of red maple (closed circles), water oak (open circles), and mixed litter (inverted solid triangle) leaf packs incubated for 128 d in Kings Mill Creek, GA, USA.
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pone.0130801.g001: Mean (± 1SE) ash free dry mass (AFDM) remaining over time during breakdown of red maple (closed circles), water oak (open circles), and mixed litter (inverted solid triangle) leaf packs incubated for 128 d in Kings Mill Creek, GA, USA.

Mentions: Over the study, mean litter breakdown rates (k) for red maple (hereafter maple), water oak (hereafter oak), and mixed litter were 0.075, 0.026 and 0.033 d-1, respectively (Fig 1). Breakdown varied significantly between leaf species (p<0.001). Maple packs contained significantly less litter over time than both oak and mixed-species packs. Mixed-species breakdown was significantly faster than oak and significantly slower than maple (Fig 1). The exponential decay model explained 85.6, 94.8, and 87.9% of the variation in maple, oak, and mixed litter breakdown, respectively (Fig 1). Maple AFDM decreased rapidly from 100 to 81.2% remaining after 1 day’s incubation. In contrast, oak showed little AFDM change over the same interval (~2% loss), and mixed litter decreased from 100 to 91.0%. After 128 d, maple had 46.6% AFDM remaining, compared to 73.9% remaining for oak and 70.5% for mixed litter packs.


Litter Breakdown and Microbial Succession on Two Submerged Leaf Species in a Small Forested Stream.

Newman MM, Liles MR, Feminella JW - PLoS ONE (2015)

Mean (± 1SE) ash free dry mass (AFDM) remaining over time during breakdown of red maple (closed circles), water oak (open circles), and mixed litter (inverted solid triangle) leaf packs incubated for 128 d in Kings Mill Creek, GA, USA.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476575&req=5

pone.0130801.g001: Mean (± 1SE) ash free dry mass (AFDM) remaining over time during breakdown of red maple (closed circles), water oak (open circles), and mixed litter (inverted solid triangle) leaf packs incubated for 128 d in Kings Mill Creek, GA, USA.
Mentions: Over the study, mean litter breakdown rates (k) for red maple (hereafter maple), water oak (hereafter oak), and mixed litter were 0.075, 0.026 and 0.033 d-1, respectively (Fig 1). Breakdown varied significantly between leaf species (p<0.001). Maple packs contained significantly less litter over time than both oak and mixed-species packs. Mixed-species breakdown was significantly faster than oak and significantly slower than maple (Fig 1). The exponential decay model explained 85.6, 94.8, and 87.9% of the variation in maple, oak, and mixed litter breakdown, respectively (Fig 1). Maple AFDM decreased rapidly from 100 to 81.2% remaining after 1 day’s incubation. In contrast, oak showed little AFDM change over the same interval (~2% loss), and mixed litter decreased from 100 to 91.0%. After 128 d, maple had 46.6% AFDM remaining, compared to 73.9% remaining for oak and 70.5% for mixed litter packs.

Bottom Line: PLFA revealed a significant time effect on microbial lipid profiles for both leaf species.Next-generation sequencing revealed temporal shifts in dominant taxa within the phylum Proteobacteria, whereas γ-Proteobacteria dominated pre-immersion and α- and β-Proteobacteria dominated after 1 month of instream incubation; the latter groups contain taxa that are predicted to be capable of using organic material to fuel further breakdown.Our results suggest that incubation time is more important than leaf species physicochemistry in influencing leaf litter microbial assemblage composition, and indicate the need for investigation into seasonal and temporal dynamics of leaf litter microbial assemblage succession.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Auburn University, Auburn, Alabama, United States of America.

ABSTRACT
Microbial succession during leaf breakdown was investigated in a small forested stream in west-central Georgia, USA, using multiple culture-independent techniques. Red maple (Acer rubrum) and water oak (Quercus nigra) leaf litter were incubated in situ for 128 days, and litter breakdown was quantified by ash-free dry mass (AFDM) method and microbial assemblage composition using phospholipid fatty acid analysis (PLFA), ribosomal intergenic spacer analysis (RISA), denaturing gradient gel electrophoresis (DGGE), and bar-coded next-generation sequencing of 16S rRNA gene amplicons. Leaf breakdown was faster for red maple than water oak. PLFA revealed a significant time effect on microbial lipid profiles for both leaf species. Microbial assemblages on maple contained a higher relative abundance of bacterial lipids than oak, and oak microbial assemblages contained higher relative abundance of fungal lipids than maple. RISA showed that incubation time was more important in structuring bacterial assemblages than leaf physicochemistry. DGGE profiles revealed high variability in bacterial assemblages over time, and sequencing of DGGE-resolved amplicons indicated several taxa present on degrading litter. Next-generation sequencing revealed temporal shifts in dominant taxa within the phylum Proteobacteria, whereas γ-Proteobacteria dominated pre-immersion and α- and β-Proteobacteria dominated after 1 month of instream incubation; the latter groups contain taxa that are predicted to be capable of using organic material to fuel further breakdown. Our results suggest that incubation time is more important than leaf species physicochemistry in influencing leaf litter microbial assemblage composition, and indicate the need for investigation into seasonal and temporal dynamics of leaf litter microbial assemblage succession.

No MeSH data available.