Inter-taxonomic differences in bacterioplankton community assembly in oligotrophic mountain lakes of east Japan

ABSTRACTpH is an important factor that shapes the structure of bacterial communities. However, we have very limited information about the patterns and processes by which overall bacterioplankton communities assemble across wide pH gradients in natural freshwater lakes. Here, we used pyrosequencing to analyze the bacterioplankton communities in 25 discrete freshwater lakes in Denmark with pH levels ranging from 3.8 to 8.8. We found that pH was the key factor impacting lacustrine bacterioplankton community assembly. More acidic lakes imposed stronger environmental filtering, which decreased the richness and evenness of bacterioplankton operational taxonomic units (OTUs) and largely shifted community composition. Although environmental filtering was determined to be the most important determinant of bacterioplankton community assembly, the importance of neutral assembly processes must also be considered, notably in acidic lakes, where the species (OTU) diversity was low. We observed that the strong effect of environmental filtering in more acidic lakes was weakened by the enhanced relative importance of neutral community assembly, and bacterioplankton communities tended to be less phylogenetically clustered in more acidic lakes. In summary, we propose that pH is a major environmental determinant in freshwater lakes, regulating the relative importance and interplay between niche-related and neutral processes and shaping the patterns of freshwater lake bacterioplankton biodiversity.

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Environmental filtering dominates bacterioplankton community assembly in a highly urbanized estuarine ecosystem

Environmental Research ◽

10.1016/j.envres.2021.110934 ◽

2021 ◽

pp. 110934

Author(s):

Lei Zhou ◽

Pengfei Wang ◽

Shihui Huang ◽

Zongyang Li ◽

Hongzhao Gong ◽

...

Keyword(s):

Community Assembly ◽

Environmental Filtering ◽

Estuarine Ecosystem ◽

Bacterioplankton Community

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Rapid and Stable Microbial Community Assembly in the Headwaters of a Third-Order Stream

Applied and Environmental Microbiology ◽

10.1128/aem.00188-19 ◽

2019 ◽

Vol 85 (11) ◽

Cited By ~ 2

Author(s):

Morgan E. Teachey ◽

Jacob M. McDonald ◽

Elizabeth A. Ottesen

Keyword(s):

Microbial Community ◽

Microbial Diversity ◽

Community Assembly ◽

Fine Scale ◽

Third Order ◽

Order Stream ◽

Bacterioplankton Community ◽

Small Streams ◽

Temporal And Spatial ◽

Over Time

ABSTRACTSmall streams and their headwaters are key sources of microbial diversity in fluvial systems and serve as an entry point for bacteria from surrounding environments. Community assembly processes occurring in these streams shape downstream population structure and nutrient cycles. To elucidate the development and stability of microbial communities along the length of a first- through third-order stream, fine-scale temporal and spatial sampling regimes were employed along McNutt Creek in Athens, GA, USA. 16S rRNA amplicon libraries were constructed from samples collected on a single day from 19 sites spanning the first 16.76 km of the stream. To provide context for this spatial study and evaluate temporal variability, selected sites at the stream’s upper, mid, and lower reaches were sampled daily for 5 days preceding and following the spatial study. In a second study, three sites at and near the creek’s headwaters were sampled daily for 11 days to understand initial bacterioplankton community assembly. Both studies revealed decreasing alpha and beta diversity with increasing downstream distance. These trends were accompanied by the enrichment of a small fraction of taxa found at low abundance in headwater-proximal sites. Similar sets of taxa consistently increased in relative abundance in downstream samples over time scales ranging from 1 day to 1 year, many of which belong to clades known to be abundant in freshwater environments. These results underpin the importance of headwaters as the site of rapid in-stream selection that results in the reproducible establishment of a highly stable community of freshwater riverine bacteria.IMPORTANCEHeadwater streams are critical introduction points of microbial diversity for larger connecting rivers and play key roles in the establishment of taxa that partake in in-stream nutrient cycling. We examined the microbial community composition of a first- through third-order stream using fine-scale temporal and spatial regimes. Our results show that the bacterioplankton community develops rapidly and predictably from the headwater population with increasing total stream length. Along the length of the stream, the microbial community exhibits substantial diversity loss and enriches repeatedly for select taxa across days and years, although the relative abundances of individual taxa vary over time and space. This repeated enrichment of a stable stream community likely contributes to the stability and flexibility of downstream communities.

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Bacterioplankton Community Composition along a Salinity Gradient of Sixteen High-Mountain Lakes Located on the Tibetan Plateau, China

Applied and Environmental Microbiology ◽

10.1128/aem.00767-06 ◽

2006 ◽

Vol 72 (8) ◽

pp. 5478-5485 ◽

Cited By ~ 205

Author(s):

Qinglong L. Wu ◽

Gabriel Zwart ◽

Michael Schauer ◽

Miranda P. Kamst-van Agterveld ◽

Martin W. Hahn

Keyword(s):

Tibetan Plateau ◽

Community Composition ◽

Denaturing Gradient Gel Electrophoresis ◽

Salinity Gradient ◽

Mountain Lakes ◽

High Mountain ◽

The Tibetan Plateau ◽

High Mountain Lakes ◽

Bacterioplankton Community ◽

Bacterial Groups

ABSTRACT The influence of altitude and salinity on bacterioplankton community composition (BCC) in 16 high-mountain lakes located at altitudes of 2,817 to 5,134 m on the Eastern Qinghai-Xizang (Tibetan) Plateau, China, spanning a salinity gradient from 0.02% (freshwater) to 22.3% (hypersaline), was investigated. Three different methods, fluorescent in situ hybridization, denaturing gradient gel electrophoresis (DGGE) with subsequent band sequencing, and reverse line blot hybridization (RLB) with probes targeting 17 freshwater bacterial groups, were used for analysis of BCC. Furthermore, the salt tolerances of 47 strains affiliated with groups detected in or isolated from the Tibetan habitats were investigated. Altitude was not found to influence BCC significantly within the investigated range. Several groups of typical freshwater bacteria, e.g., the ACK-M1 cluster and the Polynucleobacter group, were detected in habitats located above 4,400 m. Salinity was found to be the dominating environmental factor controlling BCC in the investigated lakes, resulting in only small overlaps in the BCCs of freshwater and hypersaline lakes. The relative abundances of different classes of Proteobacteria showed a sharp succession along the salinity gradient. Both DGGE and RLB demonstrated that a few freshwater bacterial groups, e.g., GKS98 and LD2, appeared over wide salinity ranges. Six freshwater isolates affiliated with the GKS98 cluster grew in ecophysiological experiments at maximum salinities of 0.3% to 0.7% (oligosaline), while this group was detected in habitats with salinities up to 6.7% (hypersaline). This observation indicated ecologically significant differences in ecophysiological adaptations among members of this narrow phylogenetic group and suggested ecological significance of microdiversity.

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Rapid and stable microbial community assembly in the headwaters of third-order stream

10.1101/426460 ◽

2018 ◽

Author(s):

Morgan E. Teachey ◽

Jacob M. McDonald ◽

Elizabeth A. Ottesen

Keyword(s):

Microbial Community ◽

Microbial Diversity ◽

Community Assembly ◽

Fine Scale ◽

Third Order ◽

Order Stream ◽

Bacterioplankton Community ◽

Small Streams ◽

Temporal And Spatial ◽

Over Time

AbstractSmall streams and their headwaters are a key source of microbial diversity in fluvial systems and serve as an entry point for bacteria from the surrounding landscape. Community assembly processes occurring in these streams shape downstream population structure and nutrient cycles. To elucidate the development and stability of microbial communities along the length of a first through third order stream, fine-scale temporal and spatial sampling regimes were employed along McNutt Creek in Athens, Georgia, USA. 16S rRNA gene libraries were constructed from samples collected on a single day from 19 sites spanning the first 16.76 km of the stream. Selected sites at the upper, mid, and lower reaches of the stream were sampled daily for 11 days to evaluate community variability over time. In a second study, sites at and near the creek’s headwaters were sampled daily for 11 days to understand the initial stages of bacterioplankton community assembly. In all studies, we observed decreasing alpha and beta diversity with increasing downstream distance. These trends were accompanied by the enrichment of a small fraction of taxa found at low abundance in the furthest-upstream environments. Similar sets of taxa consistently increased significantly in relative abundance in downstream samples over time scales ranging from 1 day to 1 year, many of which belong to microbial clades known to be abundant in freshwater environments. These results underpin the importance of headwaters as the site of rapid in-stream selection that results in the reproducible establishment of a highly stable community of freshwater riverine bacteria.ImportanceHeadwater streams are critical introduction points of microbial diversity for larger connecting rivers and play key roles in the establishment of taxa that partake in in-stream nutrient cycling. We examined microbial community composition of a first- through third-order stream using fine-scale temporal and spatial regimes. Our results show that the bacterioplankton community develops rapidly and predictably from the headwater population with increasing total stream length. Along the length of the stream, the microbial community exhibits substantial diversity loss and enriches repeatedly for select taxa across days and years, although the relative abundances of individual taxa vary over time and space. This repeated enrichment of a stable stream community likely contributes to the stability and flexibility of downstream communities.

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Experimentally altered rainfall regimes and host root traits affect grassland arbuscular mycorrhizal fungal communities

10.32942/osf.io/cu4jh ◽

2019 ◽

Author(s):

Coline Deveautour ◽

Suzanne Donn ◽

Sally Power ◽

Kirk Barnett ◽

Jeff Powell

Keyword(s):

Fungal Community ◽

Community Assembly ◽

Root Length ◽

Specific Root Length ◽

Root Traits ◽

Arbuscular Mycorrhizal ◽

Fungal Communities ◽

Rainfall Regime ◽

Precipitation Regimes ◽

Rainfall Regimes

Future climate scenarios predict changes in rainfall regimes. These changes are expected to affect plants via effects on the expression of root traits associated with water and nutrient uptake. Associated microorganisms may also respond to these new precipitation regimes, either directly in response to changes in the soil environment or indirectly in response to altered root trait expression. We characterised arbuscular mycorrhizal (AM) fungal communities in an Australian grassland exposed to experimentally altered rainfall regimes. We used Illumina sequencing to assess the responses of AM fungal communities associated with four plant species sampled in different watering treatments and evaluated the extent to which shifts were associated with changes in root traits. We observed that altered rainfall regimes affected the composition but not the richness of the AM fungal communities, and we found distinctive communities in the increased rainfall treatment. We found no evidence of altered rainfall regime effects via changes in host physiology because none of the studied traits were affected by changes in rainfall. However, specific root length was observed to correlate with AM fungal richness, while concentrations of phosphorus and calcium in root tissue and the proportion of root length allocated to fine roots were correlated to community composition. Our study provides evidence that climate change and its effects on rainfall may influence AM fungal community assembly, as do plant traits related to plant nutrition and water uptake. We did not find evidence that host responses to altered rainfall drive AM fungal community assembly in this grassland ecosystem.

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