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Microbial community composition of transiently wetted Antarctic Dry Valley soils.

Niederberger TD, Sohm JA, Gunderson TE, Parker AE, Tirindelli J, Capone DG, Carpenter EJ, Cary SC - Front Microbiol (2015)

Bottom Line: Soil water content decreased to below ~3% in the arid soils.Community fingerprinting-based principle component analyses revealed that bacterial communities formed distinct clusters specific to arid and wet soils; however, eukaryotic communities that clustered together did not have similar soil moisture content nor did they group together based on sampling location.Results indicate that the repeated wetting of hyporheic zones has a profound impact on the bacterial and eukaryotic communities inhabiting in these areas.

View Article: PubMed Central - PubMed

Affiliation: College of Marine and Earth Sciences, University of Delaware Lewes, DE, USA.

ABSTRACT
During the summer months, wet (hyporheic) soils associated with ephemeral streams and lake edges in the Antarctic Dry Valleys (DVs) become hotspots of biological activity and are hypothesized to be an important source of carbon and nitrogen for arid DV soils. Recent research in the DV has focused on the geochemistry and microbial ecology of lakes and arid soils, with substantially less information being available on hyporheic soils. Here, we determined the unique properties of hyporheic microbial communities, resolved their relationship to environmental parameters and compared them to archetypal arid DV soils. Generally, pH increased and chlorophyll a concentrations decreased along transects from wet to arid soils (9.0 to ~7.0 for pH and ~0.8 to ~5 μg/cm(3) for chlorophyll a, respectively). Soil water content decreased to below ~3% in the arid soils. Community fingerprinting-based principle component analyses revealed that bacterial communities formed distinct clusters specific to arid and wet soils; however, eukaryotic communities that clustered together did not have similar soil moisture content nor did they group together based on sampling location. Collectively, rRNA pyrosequencing indicated a considerably higher abundance of Cyanobacteria in wet soils and a higher abundance of Acidobacterial, Actinobacterial, Deinococcus/Thermus, Bacteroidetes, Firmicutes, Gemmatimonadetes, Nitrospira, and Planctomycetes in arid soils. The two most significant differences at the genus level were Gillisia signatures present in arid soils and chloroplast signatures related to Streptophyta that were common in wet soils. Fungal dominance was observed in arid soils and Viridiplantae were more common in wet soils. This research represents an in-depth characterization of microbial communities inhabiting wet DV soils. Results indicate that the repeated wetting of hyporheic zones has a profound impact on the bacterial and eukaryotic communities inhabiting in these areas.

No MeSH data available.


Related in: MedlinePlus

Percentage composition of bacterial communities as based 16S rRNA-based amplicon pyrosequencing. The category ‘Other’ includes the phyla: BRC1, OD1, TM7, OP10, Nitrospira, SR1, and WS3. The total number of sequences for each sample: NP4, 7236; NP2, 24000; MS1-3, 5142; MS1-2, 10366; ML1-4, 7163; ML1-2, 7640; BL4, 9957; BL2, 7033.
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Figure 3: Percentage composition of bacterial communities as based 16S rRNA-based amplicon pyrosequencing. The category ‘Other’ includes the phyla: BRC1, OD1, TM7, OP10, Nitrospira, SR1, and WS3. The total number of sequences for each sample: NP4, 7236; NP2, 24000; MS1-3, 5142; MS1-2, 10366; ML1-4, 7163; ML1-2, 7640; BL4, 9957; BL2, 7033.

Mentions: To further elucidate differences in microbial community structure between wet and arid soils, amplicon pyrosequencing of bacterial and eukaryotic rRNA genes was undertaken on wet and arid soil samples from representative transects collected in January 2009 (transects: BL, ML1) and December 2009 (transects: MS1 and NP). These sites were selected based on clustering PCA results (i.e., wet vs. dry sites were distinctly separated in PCA results) and it was ensured that both a wet and arid site from the same transect was sequenced. Rarefaction analyses at 95% for all sites indicate adequate sampling size with curves reaching or nearing plateau (results not shown). Obvious differences in bacterial composition between wet and dry soil biotopes include increased representation of Acidobacteria and Actinobacteria in arid soils and, with the exception of NP, cyanobacteria being more highly represented in wetter soils (Figure 3). Specifically, Acidobacteria comprised ~<2.5% of the total signatures detected in wet soils and 1.3–11.0% in arid soils while Actinobacteria comprised ~<7.5% in wet soils and ~4.7–37.0% in arid soils. As expected, Cyanobacteria comprised ~10–47% of the total sequences in wet soils that had visible microbial crusts and <7% for arid soils of BL, ML, MS (~33% for NP). Of note, the Deinococcus-Thermus group was generally present in arid soils (0.09–6.0%), but very low to undetected in the wet soils (<0.02%).


Microbial community composition of transiently wetted Antarctic Dry Valley soils.

Niederberger TD, Sohm JA, Gunderson TE, Parker AE, Tirindelli J, Capone DG, Carpenter EJ, Cary SC - Front Microbiol (2015)

Percentage composition of bacterial communities as based 16S rRNA-based amplicon pyrosequencing. The category ‘Other’ includes the phyla: BRC1, OD1, TM7, OP10, Nitrospira, SR1, and WS3. The total number of sequences for each sample: NP4, 7236; NP2, 24000; MS1-3, 5142; MS1-2, 10366; ML1-4, 7163; ML1-2, 7640; BL4, 9957; BL2, 7033.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4309182&req=5

Figure 3: Percentage composition of bacterial communities as based 16S rRNA-based amplicon pyrosequencing. The category ‘Other’ includes the phyla: BRC1, OD1, TM7, OP10, Nitrospira, SR1, and WS3. The total number of sequences for each sample: NP4, 7236; NP2, 24000; MS1-3, 5142; MS1-2, 10366; ML1-4, 7163; ML1-2, 7640; BL4, 9957; BL2, 7033.
Mentions: To further elucidate differences in microbial community structure between wet and arid soils, amplicon pyrosequencing of bacterial and eukaryotic rRNA genes was undertaken on wet and arid soil samples from representative transects collected in January 2009 (transects: BL, ML1) and December 2009 (transects: MS1 and NP). These sites were selected based on clustering PCA results (i.e., wet vs. dry sites were distinctly separated in PCA results) and it was ensured that both a wet and arid site from the same transect was sequenced. Rarefaction analyses at 95% for all sites indicate adequate sampling size with curves reaching or nearing plateau (results not shown). Obvious differences in bacterial composition between wet and dry soil biotopes include increased representation of Acidobacteria and Actinobacteria in arid soils and, with the exception of NP, cyanobacteria being more highly represented in wetter soils (Figure 3). Specifically, Acidobacteria comprised ~<2.5% of the total signatures detected in wet soils and 1.3–11.0% in arid soils while Actinobacteria comprised ~<7.5% in wet soils and ~4.7–37.0% in arid soils. As expected, Cyanobacteria comprised ~10–47% of the total sequences in wet soils that had visible microbial crusts and <7% for arid soils of BL, ML, MS (~33% for NP). Of note, the Deinococcus-Thermus group was generally present in arid soils (0.09–6.0%), but very low to undetected in the wet soils (<0.02%).

Bottom Line: Soil water content decreased to below ~3% in the arid soils.Community fingerprinting-based principle component analyses revealed that bacterial communities formed distinct clusters specific to arid and wet soils; however, eukaryotic communities that clustered together did not have similar soil moisture content nor did they group together based on sampling location.Results indicate that the repeated wetting of hyporheic zones has a profound impact on the bacterial and eukaryotic communities inhabiting in these areas.

View Article: PubMed Central - PubMed

Affiliation: College of Marine and Earth Sciences, University of Delaware Lewes, DE, USA.

ABSTRACT
During the summer months, wet (hyporheic) soils associated with ephemeral streams and lake edges in the Antarctic Dry Valleys (DVs) become hotspots of biological activity and are hypothesized to be an important source of carbon and nitrogen for arid DV soils. Recent research in the DV has focused on the geochemistry and microbial ecology of lakes and arid soils, with substantially less information being available on hyporheic soils. Here, we determined the unique properties of hyporheic microbial communities, resolved their relationship to environmental parameters and compared them to archetypal arid DV soils. Generally, pH increased and chlorophyll a concentrations decreased along transects from wet to arid soils (9.0 to ~7.0 for pH and ~0.8 to ~5 μg/cm(3) for chlorophyll a, respectively). Soil water content decreased to below ~3% in the arid soils. Community fingerprinting-based principle component analyses revealed that bacterial communities formed distinct clusters specific to arid and wet soils; however, eukaryotic communities that clustered together did not have similar soil moisture content nor did they group together based on sampling location. Collectively, rRNA pyrosequencing indicated a considerably higher abundance of Cyanobacteria in wet soils and a higher abundance of Acidobacterial, Actinobacterial, Deinococcus/Thermus, Bacteroidetes, Firmicutes, Gemmatimonadetes, Nitrospira, and Planctomycetes in arid soils. The two most significant differences at the genus level were Gillisia signatures present in arid soils and chloroplast signatures related to Streptophyta that were common in wet soils. Fungal dominance was observed in arid soils and Viridiplantae were more common in wet soils. This research represents an in-depth characterization of microbial communities inhabiting wet DV soils. Results indicate that the repeated wetting of hyporheic zones has a profound impact on the bacterial and eukaryotic communities inhabiting in these areas.

No MeSH data available.


Related in: MedlinePlus