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.


Dendrogram of ribosomal intergenic spacer analysis (RISA) electropherograms displaying bacterial assemblage similarities calculated using Ward’s method based on Jaccard’s similarity coefficient.
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pone.0130801.g004: Dendrogram of ribosomal intergenic spacer analysis (RISA) electropherograms displaying bacterial assemblage similarities calculated using Ward’s method based on Jaccard’s similarity coefficient.

Mentions: Analysis of bacterial assemblage composition using RISA showed little dependence on leaf species (p = 0.076); in contrast, composition varied strongly by date (p<0.001, Fig 4). PLFA also indicated high variation in lipid profiles over time for both maple and oak (p = 0.001 and 0.005, respectively). Cluster analysis of RISA data clearly defined 3 temporal groupings of bacterial assemblages, pre-immersion, early breakdown, and later breakdown assemblages (Fig 4). Jackknife-based UPGMA clustering of weighted and unweighted UniFrac distances, calculated from next-generation 16S rRNA gene sequence data, both suggested structuring of bacterial assemblages into 3 temporal groupings. There was no overall effect of leaf species on bacterial assemblage structure (unweighted p = 0.525; weighted p = 0.605) based on next-generation 16S rRNA gene sequence data, although as with PLFA, assemblage structure varied strongly with date (p<0.001) (Fig 5).


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

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

Dendrogram of ribosomal intergenic spacer analysis (RISA) electropherograms displaying bacterial assemblage similarities calculated using Ward’s method based on Jaccard’s similarity coefficient.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130801.g004: Dendrogram of ribosomal intergenic spacer analysis (RISA) electropherograms displaying bacterial assemblage similarities calculated using Ward’s method based on Jaccard’s similarity coefficient.
Mentions: Analysis of bacterial assemblage composition using RISA showed little dependence on leaf species (p = 0.076); in contrast, composition varied strongly by date (p<0.001, Fig 4). PLFA also indicated high variation in lipid profiles over time for both maple and oak (p = 0.001 and 0.005, respectively). Cluster analysis of RISA data clearly defined 3 temporal groupings of bacterial assemblages, pre-immersion, early breakdown, and later breakdown assemblages (Fig 4). Jackknife-based UPGMA clustering of weighted and unweighted UniFrac distances, calculated from next-generation 16S rRNA gene sequence data, both suggested structuring of bacterial assemblages into 3 temporal groupings. There was no overall effect of leaf species on bacterial assemblage structure (unweighted p = 0.525; weighted p = 0.605) based on next-generation 16S rRNA gene sequence data, although as with PLFA, assemblage structure varied strongly with date (p<0.001) (Fig 5).

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.