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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) % relative abundance (%) of fungal lipid markers of red maple and water oak leaf packs over the 128-d incubation In Kings Mill Creek, GA, USA.(* = p<0.001, ns = not significantly different).
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pone.0130801.g003: Mean (± 1SE) % relative abundance (%) of fungal lipid markers of red maple and water oak leaf packs over the 128-d incubation In Kings Mill Creek, GA, USA.(* = p<0.001, ns = not significantly different).

Mentions: Relative bacterial and fungal lipid abundance, estimated by FAME analysis, differed significantly between maple and oak on all dates except day 128 (Figs 2 and 3). Overall, bacterial lipid relative abundance on maple was higher than oak (p<0.001, Fig 2), whereas oak showed higher fungal lipid relative abundance than maple (p<0.001, Fig 3). Fungal lipid relative abundance on oak tended to decrease over the incubation, whereas bacterial lipid abundance steadily increased (Fig 3). Bar-coded next-generation sequencing yielded 195,835 paired-end sequences with quality scores >20 and a mean of 11,311 sequences per sample. The number of observed bacterial OTUs, based on bar-coded next-generation sequence data, increased over time for both species, ranging from ~337 OTUs on day 0 to ~979 OTUs on day 128 for maple and ~463 OTUs on day 0 to ~775 OTUs on day 128 for oak. There was no effect of leaf species on any bacterial alpha diversity measure (p>0.05 for all metrics), but all 4 alpha diversity metrics varied over time (p<0.001, Table 1). However, there was no species-date interaction for any bacterial alpha diversity metric (p>0.05 for all metrics, Table 1).


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) % relative abundance (%) of fungal lipid markers of red maple and water oak leaf packs over the 128-d incubation In Kings Mill Creek, GA, USA.(* = p<0.001, ns = not significantly different).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130801.g003: Mean (± 1SE) % relative abundance (%) of fungal lipid markers of red maple and water oak leaf packs over the 128-d incubation In Kings Mill Creek, GA, USA.(* = p<0.001, ns = not significantly different).
Mentions: Relative bacterial and fungal lipid abundance, estimated by FAME analysis, differed significantly between maple and oak on all dates except day 128 (Figs 2 and 3). Overall, bacterial lipid relative abundance on maple was higher than oak (p<0.001, Fig 2), whereas oak showed higher fungal lipid relative abundance than maple (p<0.001, Fig 3). Fungal lipid relative abundance on oak tended to decrease over the incubation, whereas bacterial lipid abundance steadily increased (Fig 3). Bar-coded next-generation sequencing yielded 195,835 paired-end sequences with quality scores >20 and a mean of 11,311 sequences per sample. The number of observed bacterial OTUs, based on bar-coded next-generation sequence data, increased over time for both species, ranging from ~337 OTUs on day 0 to ~979 OTUs on day 128 for maple and ~463 OTUs on day 0 to ~775 OTUs on day 128 for oak. There was no effect of leaf species on any bacterial alpha diversity measure (p>0.05 for all metrics), but all 4 alpha diversity metrics varied over time (p<0.001, Table 1). However, there was no species-date interaction for any bacterial alpha diversity metric (p>0.05 for all metrics, Table 1).

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.