Bacterial Community Composition in Oligosaline Lake Bosten: Low Overlap of Betaproteobacteria and Bacteroidetes with Freshwater Ecosystems (original) (raw)
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SpringerPlus, 2016
Bacteria play a vital role in various biogeochemical processes in lacustrine sediment ecosystems. This study is among the first to investigate the spatial distribution patterns of bacterial community composition in the sediments of Poyang Lake, the largest freshwater lake of China. Sediment samples were collected from the main basins and mouths of major rivers that discharge into the Poyang Lake in May 2011. Quantitative PCR assay and pyrosequencing analysis of 16S rRNA genes showed that the bacteria community abundance and compositions of Poyang Lake sediment varied largely among sampling sites. A total of 25 phyla and 68 bacterial orders were distinguished. Burkholderiales, Gallionellales (Beta-proteobacteria), Myxococcales, Desulfuromonadales (Delta-proteobacteria), Sphingobacteriales (Bacteroidetes), Nitrospirales (Nitrospirae), Xanthomonadales (Gamma-proteobacteria) were identified as the major taxa and collectively accounted for over half of annotated sequences. Moreover, corr...
Microorganisms
In recent years, climate change coupled with anthropogenic activities has led to monumental changes in saline lakes which are rapidly drying up across the globe and particularly in Central Asia. The landlocked country of Mongolia is rich in lakes which have remained primarily undisturbed by human impact, and many of these lakes have varying salinity regimes and are located across various geographical landscapes. In this study, we sampled 18 lakes with varying salinity regimes (hyperhaline, mesohaline, oligohaline, and polyhaline) covering 7000 km of western Mongolia and its various geographical landscapes (Gobi Desert, forests, and steppe). We identified that the bacterial communities that dominate these lakes are significantly influenced by salinity (p < 0.001) and geographical landscape (p < 0.001). Further, only five zOTUs were shared in all the lakes across the salinity regimes, providing evidence that both local and regional factors govern the community assembly and compo...
Functional profiling of bacterial communities in Lake Tuz using 16S rRNA gene sequences
Biotechnology & Biotechnological Equipment
The 16S rRNA amplicon sequencing technique is a key aspect of studies of microbial communities but does not provide direct evidence of a community's functional capabilities. This work aimed to assess the structure of the uncultured bacterial communities from two locations in Lake Tuz in Turkey to provide information on their roles in the lake ecosystem. The most abundant phyla in the lake water were Firmicutes (84%) for lake sample site 1 (TG1), 70% for lake sample site 2 (TG2), Fusobacteria (9% for TG1, 22% for TG2) and Proteobacteria (6% for TG1, 7% for TG2). The most abundant genera were Romboutsia (45% for TG1, 35% for TG2), Clostridium sensu stricto 1 (8% for TG1, 8% for TG2), Cetobacterium (9% for TG1, 22% for TG2) and Photobacterium (2% for TG1, 3% for TG2). PICRUSt constitutes a novel bioinformatics tool to establish profiles for bacterial protein functions based on metagenomic 16S rRNA data for a community of unculturable bacteria. PICRUSt also provides information on whole-community metabolic functions related to adaptation, bioremediation potential and the ability of various groups of microorganisms to survive in highly saline water. The overall results provide an effective strategy for assessing the metabolic capacities of microbes in situ in a high-salt aquatic environment such as Lake Tuz and the potential of these microbes to serve as bioremediation agents. This approach provides useful insights into predictive metagenomics of an unculturable microbial community for which only marker-gene surveys are currently available.
Genome-resolved community structure and function of freshwater bacteria at a continental scale
Lakes are highly heterogenous ecosystems inhabited by a rich microbiome whose genomic diversity remains poorly defined compared to other major biomes. Here, we present a continental-scale study of metagenomes collected across one of the most lake-rich landscapes on Earth. Analysis of 308 Canadian lakes resulted in a metagenome-assembled genome (MAG) catalogue of 1,008 bacterial genomospecies spanning a broad phylogenetic and metabolic diversity. Lake trophic state was a significant determinant of taxonomic and functional turnover of MAG assemblages. We detected a role for resource availability, particularly carbohydrate diversity, in driving biogeographic patterns. Coupling the MAG catalogue with geomatics information on watershed characteristics revealed an influence of soil properties and human land use on MAG assemblages. Agriculture and human population density were particularly influential on MAG functional turnover, signifying a detectable human footprint in lake bacterial com...
Structure of bacterial communities in diverse freshwater habitats
Canadian Journal of Microbiology, 2012
The structures and dynamics of bacterial communities from raw source water, groundwater, and drinking water before and after filtration were studied in four seasons of a year, with culture-independent methods. Genomic DNA from water samples was analyzed by the polymerase chain reaction – denaturing gradient gel electrophoresis system and by cloning of the 16S rRNA gene. Water samples exhibited complex denaturing gradient gel electrophoresis genetic profiles composed of many bands, corresponding to a great variety of bacterial taxa. The bacterial communities of different seasons from the four sampling sites clustered into two major groups: (i) water before and after filtration, and (ii) source water and groundwater. Phylogenetic analyses of the clones from the autumn sampling revealed 13 phyla, 19 classes, and 155 operational taxonomic units. Of the clones, 66% showed less than 97% similarities to known bacterial species. Representatives of the phyla Proteobacteria, Bacteroidetes, an...
Geomicrobiology Journal, 2013
The influence of salinity and geographical distance on bacterial community composition (BCC) in five freshwater, oligosaline or polysaline lakes located at altitudes higher than 4400 m on the central and southern Tibetan Plateau were investigated using the 16S rRNA gene clone library approach together with multivariate analysis of environmental variables. A total of 10 clone libraries were constructed with two libraries in each lake, one in the epilimnion and the other in the hypolimnion. Geographical distance was not found to impact BCC significantly, but salinity, chl a and lake hydraulic retention time were significant factors influencing the BCC. Bacteria in lakes located on the central and southern Plateau owned the same community composition as that observed from the eastern Tibetan lakes. They were both predominated by Bacteroidetes and Cyanobacteria, had low taxon richness, and similar typical freshwater clusters and distributed characteristics.
Microbial Biogeography of Six Salt Lakes in Inner Mongolia, China, and a Salt Lake in Argentina
Applied and Environmental Microbiology, 2009
We used cultivation-independent methods to investigate the prokaryotic biogeography of the water column in six salt lakes in Inner Mongolia, China, and a salt lake in Argentina. These lakes had different salt compositions and pH values and were at variable geographic distances, on both local and intercontinental scales, which allowed us to explore the microbial community composition within the context of both contemporary environmental conditions and geographic distance. Fourteen 16S rRNA gene clone libraries were constructed, and over 200 16S rRNA gene sequences were obtained. These sequences were used to construct biotic similarity matrices, which were used in combination with environmental similarity matrices and a distance matrix in the Mantel test to discover which factors significantly influenced biotic similarity. We showed that archaeal biogeography was influenced by contemporary environmental factors alone (Na ؉ , CO 3 2؊ , and HCO 3 ؊ ion concentrations; pH; and temperature). Bacterial biogeography was influenced both by contemporary environmental factors (Na ؉ , Mg 2؉ , and HCO 3 ؊ ion concentrations and pH) and by geographic distance.
Limnology and Oceanography, 2010
To investigate the spatial and temporal variations of organic-aggregate-associated bacterial communities (OABC), a 25-month observation was conducted at two contrasting sites (Meiliang Bay and the lake center) in Lake Taihu, China. The structures and dynamics of the OABC were determined by partially sequencing cloned 16S rRNA genes, and by terminal restriction fragment length polymorphism (T-RFLP) analysis. One hundred ninety-two T-RFs were detected from the two sites, but only 17 T-RFs were dominant, suggesting that specific microbial populations were adapted to the unique niche provided by the organic aggregates (OA). Phylogenetically, Beta-and Alphaproteobacteria constituted the numerically most important heterotrophic bacterial group. Analysis of similarity revealed significant intra-lake heterogeneity, and significant temporal shifts in OABC. Canonical correspondence analysis demonstrated that site-specific differences in sediment resuspension and nutrient enrichment (namely nitrate and total phosphorus) were the forces driving the intra-lake differences in OABC. Water temperature and dissolved oxygen were related to the seasonal dynamics of OABC. The annual succession in OABC was significant in Meiliang Bay, but not in the lake center. In addition, nearly 35% of the bacterial sequences from OA related to bacteria from soils, activated sludge, sediments, and other habitats, indicating the potential importance of allochthonous bacteria in OABC.
Frontiers in Microbiology, 2016
Modern microbialites are complex microbial communities that interface with abiotic factors to form carbonate-rich organosedimentary structures whose ancestors provide the earliest evidence of life. Past studies primarily on marine microbialites have inventoried diverse taxa and metabolic pathways, but it is unclear which of these are members of the microbialite community and which are introduced from adjacent environments. Here we control for these factors by sampling the surrounding water and nearby sediment, in addition to the microbialites and use a metagenomics approach to interrogate the microbial community. Our findings suggest that the Pavilion Lake microbialite community profile, metabolic potential and pathway distributions are distinct from those in the neighboring sediments and water. Based on RefSeq classification, members of the Proteobacteria (e.g., alpha and delta classes) were the dominant taxa in the microbialites, and possessed novel functional guilds associated with the metabolism of heavy metals, antibiotic resistance, primary alcohol biosynthesis and urea metabolism; the latter may help drive biomineralization. Urea metabolism within Pavilion Lake microbialites is a feature not previously associated in other microbialites. The microbialite communities were also significantly enriched for cyanobacteria and acidobacteria, which likely play an important role in biomineralization. Additional findings suggest that Pavilion Lake microbialites are under viral selection as genes associated with viral infection (e.g CRISPR-Cas, phage shock and phage excision) are abundant within the microbialite metagenomes. The morphology of Pavilion Lake microbialites changes dramatically with depth; yet, metagenomic data did not vary significantly by morphology or depth, indicating that microbialite morphology is altered by other factors, perhaps transcriptional differences or abiotic conditions. This work provides a comprehensive metagenomic perspective of the interactions and differences between microbialites and their surrounding environment, and reveals the distinct nature of these complex communities.