Publications

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    ABSTRACT: The CRISPR-Cas9 system is a powerful and revolutionary genome-editing tool for eukaryotic genomes but its use in bacterial genomes is very limited. Here we investigated the use of the Streptococcus pyogenes CRISPR-Cas9 system in editing the genome of Clostridium cellulolyticum, a model microorganism for bioenergy research. Wildtype Cas9-induced double-strand breaks were lethal to C. cellulolyticum due to the minimal expression of non-homologous end joining (NHEJ) components in this strain. To circumvent this lethality, Cas9 nickase was applied to develop a single nick-triggered homologous recombination strategy, which allows precise one-step editing at intended genomic loci by transforming a single vector. This strategy has a high editing efficiency (>95%) even using short homologous arms (0.2 kb), is able to markerlessly deliver foreign genes into the genome in a single step, enables precise editing even at two very similar target sites differing by two bases preceding the seed region, and has a very high target site density (median interval distance of 9 bp and 95.7% gene coverage in C. cellulolyticum). Together, these results establish a simple and robust methodology for genome editing in NHEJ-ineffective prokaryotes. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Applied and Environmental Microbiology 04/2015; DOI:10.1128/AEM.00873-15 · 3.95 Impact Factor
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    ABSTRACT: To investigate the genetic basis of microbial evolutionary adaptation to salt (NaCl) stress, populations of Desulfovibrio vulgaris Hildenborough (DvH), a sulfate-reducing bacterium important for the biogeochemical cycling of sulfur, carbon and nitrogen, and potentially the bioremediation of toxic heavy metals and radionuclides, were propagated under salt stress or non-stress conditions for 1200 generations. Whole-genome sequencing revealed 11 mutations in salt stress-evolved clone ES9-11 and 14 mutations in non-stress-evolved clone EC3-10. Whole-population sequencing data suggested the rapid selective sweep of the pre-existing polymorphisms under salt stress within the first 100 generations and the slow fixation of new mutations. Population genotyping data demonstrated that the rapid selective sweep of pre-existing polymorphisms was common in salt stress-evolved populations. In contrast, the selection of pre-existing polymorphisms was largely random in EC populations. Consistently, at 100 generations, stress-evolved population ES9 showed improved salt tolerance, namely increased growth rate (2.0-fold), higher biomass yield (1.8-fold) and shorter lag phase (0.7-fold) under higher salinity conditions. The beneficial nature of several mutations was confirmed by site-directed mutagenesis. All four tested mutations contributed to the shortened lag phases under higher salinity condition. In particular, compared with the salt tolerance improvement in ES9-11, a mutation in a histidine kinase protein gene lytS contributed 27% of the growth rate increase and 23% of the biomass yield increase while a mutation in hypothetical gene DVU2472 contributed 24% of the biomass yield increase. Our results suggested that a few beneficial mutations could lead to dramatic improvements in salt tolerance.The ISME Journal advance online publication, 7 April 2015; doi:10.1038/ismej.2015.45.
    The ISME Journal 04/2015; DOI:10.1038/ismej.2015.45 · 9.27 Impact Factor
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    ABSTRACT: Spatial scaling is a critical issue in ecology, but how anthropogenic activities like fertilization affect spatial scaling is poorly understood, especially for microbial communities. Here, we determined the effects of long-term fertilization on the spatial scaling of microbial functional diversity and its relationships to plant diversity in the 150-year-old Park Grass Experiment, the oldest continuous grassland experiment in the world. Nested samples were taken from plots with contrasting inorganic fertilization regimes, and community DNAs were analyzed using the GeoChip-based functional gene array. The slopes of microbial gene-area relationships (GARs) and plant species-area relationships (SARs) were estimated in a plot receiving nitrogen (N), phosphorus (P), and potassium (K) and a control plot without fertilization. Our results indicated that long-term inorganic fertilization significantly increased both microbial GARs and plant SARs. Microbial spatial turnover rates (i.e., z values) were less than 0.1 and were significantly higher in the fertilized plot (0.0583) than in the control plot (0.0449) (P < 0.0001). The z values also varied significantly with different functional genes involved in carbon (C), N, P, and sulfur (S) cycling and with various phylogenetic groups (archaea, bacteria, and fungi). Similarly, the plant SARs increased significantly (P < 0.0001), from 0.225 in the control plot to 0.419 in the fertilized plot. Soil fertilization, plant diversity, and spatial distance had roughly equal contributions in shaping the microbial functional community structure, while soil geochemical variables contributed less. These results indicated that long-term agricultural practice could alter the spatial scaling of microbial biodiversity. Determining the spatial scaling of microbial biodiversity and its response to human activities is important but challenging in microbial ecology. Most studies to date are based on different sites that may not be truly comparable or on short-term perturbations, and hence, the results observed could represent transient responses. This study examined the spatial patterns of microbial communities in response to different fertilization regimes at the Rothamsted Research Experimental Station, which has become an invaluable resource for ecologists, environmentalists, and soil scientists. The current study is the first showing that long-term fertilization has dramatic impacts on the spatial scaling of microbial communities. By identifying the spatial patterns in response to long-term fertilization and their underlying mechanisms, this study makes fundamental contributions to predictive understanding of microbial biogeography. Copyright © 2015 Liang et al.
    mBio 04/2015; 6(2). DOI:10.1128/mBio.00240-15 · 6.88 Impact Factor
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    ABSTRACT: Cr(VI) is a widespread environmental contaminant that is highly toxic and soluble. Previous work indicated that a one-time amendment of polylactate hydrogen-release compound (HRC) reduced groundwater Cr(VI) concentrations for >3.5 years at a contaminated aquifer; however, microbial communities responsible for Cr(VI) reduction are poorly understood. In this study, we hypothesized that HRC amendment would significantly change the composition and structure of groundwater microbial communities, and that the abundance of key functional genes involved in HRC degradation and electron acceptor reduction would increase for a long term in response to this slowly-degrading, complex substrate. To test these hypotheses, groundwater microbial communities were monitored after HRC amendment for >1 year using a comprehensive functional gene microarray. The results showed that the overall functional composition and structure of groundwater microbial communities underwent sequential shifts after HRC amendment. Particularly, the abundance of functional genes involved in acetate oxidation, denitrification, dissimilatory nitrate reduction, metal reduction, and sulfate reduction significantly increased. The overall community dynamics was significantly correlated with changes in groundwater concentrations of microbial biomass, acetate, NO3-, Cr(VI), Fe(II) and SO42-. Our results suggest that HRC amendment primarily stimulated key functional processes associated with HRC degradation and reduction of multiple electron acceptors in the aquifer towards long-term Cr(VI) reduction.
    Environmental Science & Technology 04/2015; DOI:10.1021/acs.est.5b00024 · 5.48 Impact Factor
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    ABSTRACT: Atmospheric CO2 concentration is continuously increasing, and previous studies have shown that elevated CO2 (eCO2) significantly impacts C3 plants and their soil microbial communities. However, little is known about effects of eCO2 on the compositional and functional structure, and metabolic potential of soil microbial communities under C4 plants. Here we showed that a C4 maize agroecosystem exposed to eCO2 for eight years shifted the functional and phylogenetic structure of soil microbial communities at both soil depths (0-5 cm and 5-15 cm) using EcoPlate and functional gene array (GeoChip 3.0) analyses. The abundances of key genes involved in carbon (C), nitrogen (N) and phosphorus (P) cycling were significantly stimulated under eCO2 at both soil depths, although some differences in carbon utilization patterns were observed between the two soil depths. Consistently, CO2 was found to be the dominant factor explaining 11.9% of the structural variation of functional genes, while depth and the interaction of depth and CO2 explained 5.2% and 3.8%, respectively. This study implies that eCO2 has profound effects on the functional structure and metabolic potential/activity of soil microbial communities associated with C4 plants, possibly leading to changes in ecosystem functioning and feedbacks to global change in C4 agroecosystems.
    Scientific Reports 03/2015; 5:9316. DOI:10.1038/srep09316 · 5.08 Impact Factor
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    ABSTRACT: The Three Gorges Dam has significantly altered ecological and environmental conditions within the reservoir region, but how these changes affect bacterioplankton structure and function is unknown. Here, three widely accepted metagenomic tools were employed to study the impact of damming on the bacterioplankton community in the Xiangxi River. Our results indicated that bacterioplankton communities were both taxonomically and functionally different between backwater and riverine sites, which represent communities with and without direct dam effects, respectively. There were many more nitrogen cycling Betaproteobacteria (e.g., Limnohabitans), and a higher abundance of functional genes and KEGG orthology (KO) groups involved in nitrogen cycling in the riverine sites, suggesting a higher level of bacterial activity involved in generating more nitrogenous nutrients for the growth of phytoplankton. Additionally, the KO categories involved in carbon and sulfur metabolism, as well as most of the detected functional genes also showed clear backwater and riverine patterns. As expected, these diversity patterns all significantly correlated with environmental characteristics, confirming that the bacterioplankton communities in the Xiangxi River were really affected by environmental changes from the Three Gorges Dam. This study provides a first comparative metagenomic insight for evaluating the impacts of the large dam on microbial function.
    Scientific Reports 02/2015; 5:8605. DOI:10.1038/srep08605 · 5.08 Impact Factor
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    ABSTRACT: Warming has been shown to cause soil carbon (C) loss in northern grasslands owing to accelerated microbial decomposition that offsets increased grass productivity. Yet, a multi-decadal survey indicated that the surface soil C stock in Tibetan alpine grasslands remained relatively stable. To investigate this inconsistency, we analyzed the feedback responses of soil microbial communities to simulated warming by soil transplant in Tibetan grasslands. Whereas microbial functional diversity decreased in response to warming, microbial community structure did not correlate with changes in temperature. The relative abundance of catabolic genes associated with nitrogen (N) and C cycling decreased with warming, most notably in genes encoding enzymes associated with more recalcitrant C substrates. By contrast, genes associated with C fixation increased in relative abundance. The relative abundance of genes associated with urease, glutamate dehydrogenase and ammonia monoxygenase (ureC, gdh and amoA) were significantly correlated with N2O efflux. These results suggest that unlike arid/semiarid grasslands, Tibetan grasslands maintain negative feedback mechanisms that preserve terrestrial C and N pools. To examine whether these trends were applicable to the whole plateau, we included these measurements in a model and verified that topsoil C stocks remained relatively stable. Thus, by establishing linkages between microbial metabolic potential and soil biogeochemical processes, we conclude that long-term C loss in Tibetan grasslands is ameliorated by a reduction in microbial decomposition of recalcitrant C substrates.
    The ISME Journal 02/2015; DOI:10.1038/ismej.2015.19 · 9.27 Impact Factor
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    ABSTRACT: Fungal communities play a major role as decomposers in the Earth's ecosystems. Their community-level responses to elevated CO2 (eCO2), one of the major global change factors impacting ecosystems, are not well understood. Using 28S rRNA gene amplicon sequencing and co-occurrence ecological network approaches, we analyzed the response of soil fungal communities in the BioCON experimental site in Minnesota, USA, in which a grassland ecosystem has been exposed to eCO2 for 12 years. Long-term eCO2 did not significantly change the overall fungal community structure and species richness, but significantly increased community evenness and diversity. Relative abundances of 119 OTUs (∼ 27% of the total captured sequences) were changed significantly. Significantly changed OTUs under eCO2 were associated with decreased overall relative abundance of Ascomycota, but increased relative abundance of Basidiomycota. Co-occurrence ecological network analysis indicated that eCO2 increased fungal community network complexity, as evidenced by higher intermodular and intramodular connectivity and shorter geodesic distance. In contrast, decreased connections for dominant fungal species were observed in the eCO2 network. Community reassembly of unrelated fungal species into highly connected dense modules was observed. Such changes in the co-occurrence network topology were significantly associated with altered soil and plant properties under eCO2, especially with increased plant biomass and NH4 (+)availability. This study provided novel insights into how eCO2 shapes soil fungal communities in grassland ecosystems. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Applied and Environmental Microbiology 01/2015; 81(7). DOI:10.1128/AEM.04040-14 · 3.95 Impact Factor
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    ABSTRACT: Networks of engineered waterways are critical in meeting growing water demands in megacities. To capture and treat rainwater in an energy-efficient manner, approaches can be developed for such networks that use ecological services from microbial communities. Traditionally, engineered waterways were regarded as homogeneous systems with little responsiveness of ecological communities and ensuing processes. This study provides ecogenomics-derived key information to explain the complexity of urban aquatic ecosystems in well-managed watersheds with densely interspersed land-use patterns. Overall, sedimentary microbial communities had higher richness and evenness compared to the suspended communities in water phase. Based on PERMANOVA analysis, variation in structure and functions of microbial communities over space within same land-use type was not significant. In contrast, it was significant between different land-use types, which had similar chemical profiles. Of the 36 environmental parameters studied spatially, only three metals, namely potassium, copper and aluminum significantly explained between 7-11 % of the variation in taxa and functions, based on Distance-based Linear Models (DistLM). The ecogenomics approach adopted here allows the identification of key drivers of microbial communities and their functions at watershed-scale. These findings can be used to enhance microbial services, which are critical to develop ecologically friendly waterways in rapidly urbanizing environments.
    Environmental Science and Technology 01/2015; 49(3). DOI:10.1021/es504531s · 5.48 Impact Factor
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    ABSTRACT: Although phytoplankton are the major source of marine dissolved organic matter (DOM), their blooms are a global problem that can greatly affect marine ecological systems, especially free-living bacteria, which are the primary DOM degraders. In this study, we analyzed free-living bacterial communities from Xiamen sea during an Akashiwo sanguine bloom using Illumina MiSeq sequencing of 16S rRNA gene amplicons. The bloom was probably stimulated by low salinity and ended after abatement of eutrophication pollution. A total of 658,446 sequence reads and 11,807 OTUs were obtained in both bloom and control samples with Alpha-proteobacteria and Gamma-proteobacteria being the predominant classes detected. The bloom decreased bacterial diversity, increased species evenness, and significantly changed the bacterial community structure. Bacterial communities within the bloom were more homogeneous than those within the control area. The bacteria stimulated by this bloom included the SAR86 and SAR116 clades and the AEGEAN-169 marine group, but a few were suppressed. In addition, many bacteria known to be associated with phytoplankton were detected only in the bloom samples. This study revealed the great influence of an A. sanguinea bloom on free-living bacterial communities, and provided new insights into the relationship between bacteria and A. sanguinea in marine ecosystems.
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    ABSTRACT: Microbial-driven biogeochemical cycles in wetlands impacted by global warming pose a potential downstream eutrophication risk. However, the consequences of ongoing warming on the functional and metabolic potential of sediment microbial communities are largely unknown. We incubated sediment samples under both ambient temperature conditions (control) and simulated warming conditions of 5°C above ambient temperature (warmed) using a novel field microcosm system. In warmed samples, we observed in situ a decreased thickness of the oxidized sediment layer and associated lower sediment redox potential. GeoChip 4.0, a comprehensive functional gene microarray, demonstrated that many functional genes that are involved in oxidation–reduction reactions and in phosphorus (P) degradation were preferentially enriched under warming conditions. The enriched genes included those genes encoding carbon monoxide dehydrogenase, acetyl-CoA carboxylase biotin carboxylase (ppc), and ribulose-1,5-bisphosphate carboxylase (Rubisco) for carbon fixation; nitrate reductases (narG) and nitrous oxide reductases (nosZ) for denitrification; cytochrome c for metal reduction; and exopolyphosphatase (ppx) for polyphosphate degradation. The redox potential was one of the most significant parameters linked to microbial functional gene structure. These results demonstrate that the enhanced hypoxia and anaerobic metabolic pathways accelerated sediment P mobilization in freshwater wetland subject to warming, raising the potential of water eutrophication.
    Hydrobiologia 01/2015; 743(1). DOI:10.1007/s10750-014-2039-6 · 2.21 Impact Factor
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    ABSTRACT: Microbe plays an important role in driving biogeochemical cycles, thus it is of great interest to understand microbial responses and feedbacks to global changes. We have recently analyzed functional potentials of soil microbial community via a high-throughput, microarray-based metagenomic tool named GeoChip 3.0 to illustrate microbial responses to global changes simulated by soil transplant and/or maize cropping. Here we describe detailed experimental design, data collection and pre-processing to support our published studies by Liu et al. [5] and Zhao et al. [14].
    12/2014; DOI:10.1016/j.gdata.2014.06.002
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    ABSTRACT: To examine microbial responses to climate change, we used a microarray-based metagenomics tool named GeoChip 4.0 to profile soil microbial functional genes along four sites/elevations of a Tibetan mountainous grassland. We found that microbial communities differed among four elevations. Soil pH, temperature, NH4+–N and vegetation diversity were four major attributes affecting soil microbial communities. Here we describe in details the experiment design, the data normalization process, soil and vegetation analyses associated with the study published on ISME Journal in 2014 [1], whose raw data have been uploaded to Gene Expression Omnibus (accession number GSM1185243).
    12/2014; 2. DOI:10.1016/j.gdata.2014.06.003
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    ABSTRACT: Serious nitrogen (N) deposition in terrestrial ecosystems causes soil acidification and changes the structure and function of the microbial community. However, it is unclear how these changes are dependent on N deposition rates, other factors induced by N (e.g., pH), and their interactions. In this study, we investigated the responses of soil prokaryotic community structure and stability after a 13-year N addition in the semi-arid Leymus chinensis steppe in Inner Mongolia, China. Our results demonstrated that the prokaryotic community structure changed at the low N addition rate of 1.75 g N m−2 yr−1; however, dramatic changes in microbial abundance, respiratory quotient, and prokaryotic diversity occurred at N addition rates of more than 5.25 g N m−2 yr−1 when the soil pH dropped below 6.0. The two patterns indicated the difference in driving forces for different microbial properties. The N-driven and pH-driven processes are likely the most important mechanisms determining the responses of bacterial community to N. Some copiotrophic/oligotrophic bacteria, e.g., Proteobacteria and Acidobacteria, changed their relative abundances with the N addition continuously even at a low rate, indicating that they were more sensitive to N directly. Some bacterial groups significantly changed their relative abundance at a high N addition rate when pH dropped below 6.0, e.g., Verrucomicrobia and Armatimonadetes, indicating that they were more sensitive to pH below 6.0. N addition altered the prokaryotic community structure through enrichment of copiotrophic bacteria (species adjustment) at low N addition rates and through enrichment of nitrophilous taxa and significant loss of diversity at high N rates. The results also demonstrated that a high N addition diminished the stability of the prokaryotic community structure and activity through reduction in species diversity and bacterial interaction. Overall, this study supported the hypothesis that the responses of prokaryota to N were dependent on deposition rates, and N-driven and pH-driven processes were the important mechanisms to control the shift of the prokaryotic community.
    Soil Biology and Biochemistry 12/2014; 79:81–90. DOI:10.1016/j.soilbio.2014.09.009 · 4.41 Impact Factor
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    ABSTRACT: Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Here, we identified important functional genes that characterize the rhizosphere microbial community to understand metabolic capabilities in the maize rhizosphere using the GeoChip-based functional gene array method. Significant differences in functional gene structure were apparent between rhizosphere and bulk soil microbial communities. Approximately half of the detected gene families were significantly (p<0.05) increased in the rhizosphere. Based on the detected gyrB genes, Gammaproteobacteria, Betaproteobacteria, Firmicutes, Bacteroidetes and Cyanobacteria were most enriched in the rhizosphere compared to those in the bulk soil. The rhizosphere niche also supported greater functional diversity in catabolic pathways. The maize rhizosphere had significantly enriched genes involv
    PLoS ONE 11/2014; 9(11-11):e112609. DOI:10.1371/journal.pone.0112609 · 3.53 Impact Factor
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    ABSTRACT: Understanding the response of permafrost microbial communities to climate warming is crucial for evaluating ecosystem feedbacks to global change. This study investigated soil bacterial and archaeal communities by Illumina MiSeq sequencing of 16S rRNA gene amplicons across a permafrost thaw gradient at different depths in Alaska with thaw progression for over three decades. Over 4.6 million passing 16S rRNA gene sequences were obtained from a total of 97 samples, corresponding to 61 known classes and 470 genera. Soil depth and the associated soil physical-chemical properties had predominant impacts on the diversity and composition of the microbial communities. Both richness and evenness of the microbial communities decreased with soil depth. Acidobacteria, Verrucomicrobia, Alpha- and Gamma-Proteobacteria dominated the microbial communities in the upper horizon, whereas abundances of Bacteroidetes, Delta-Proteobacteria and Firmicutes increased toward deeper soils. Effects of thaw progression were absent in microbial communities in the near-surface organic soil, likely due to greater temperature variation. Thaw progression decreased the abundances of the majority of the associated taxa in the lower organic soil, but increased the abundances of those in the mineral soil, including groups potentially involved in recalcitrant C degradation (Actinomycetales, Chitinophaga, etc.). The changes in microbial communities may be related to altered soil C sources by thaw progression. Collectively, this study revealed different impacts of thaw in the organic and mineral horizons, and suggests the importance of studying both the upper and deeper soils while evaluating microbial responses to permafrost thaw.This article is protected by copyright. All rights reserved.
    Molecular Ecology 11/2014; 24(1). DOI:10.1111/mec.13015 · 5.84 Impact Factor
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    ABSTRACT: Characteristics of a microbial community are important as they indicate the status of aquatic ecosystems. In the present study, the metabolic and phylogenetic profile of the bacterioplankton community in Guishan coastal water (Pearl River Estuary), South China Sea, at 12 sites (S1-S12) were explored by community-level physiological profiling (CLPP) with BIOLOG Eco-plate and denaturing gradient gel electrophoresis (DGGE). Our results showed that the core mariculture area (S6, S7 and S8) and the sites associating with human activity and sewage discharge (S11 and S12) had higher microbial metabolic capability and bacterial community diversity than others (S1-5, S9-10). Especially, the diversity index of S11 and S12 calculated from both CLPP and DGGE data (H>3.2) was higher than that of others as sewage discharge may increase water nitrogen and phosphorus nutrient. The bacterial community structure of S6, S8, S11 and S12 was greatly influenced by total phosphorous, salinity and total nitrogen. Based on DGGE fingerprinting, proteobacteria, especially γ- and α-proteobacteria, were found dominant at all sites. In conclusion, the aquaculture area and wharf had high microbial metabolic capability. The structure and composition of bacterial community were closely related to the level of phosphorus, salinity and nitrogen.
    Journal of Ocean University of China 10/2014; 13(5). DOI:10.1007/s11802-014-2294-1 · 0.38 Impact Factor
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    ABSTRACT: We have begun investigations on microbial communities from Alaskan tundra permafrost (AK) and Oklahoma temperate grassland (OK) soils, both of which have been experimentally warmed in-situ 2 °C above ambient temperature for one year. Our analyses of well-replicated 16S rRNA gene amplicon, meta-transcriptomic, and whole-community shotgun metagenomic datasets from these soils showed small but significant shifts in community composition, gene expression, and functional metabolic potential compared to control (un-warmed) adjacent communities. Greater taxonomic compositional differences were observed at the OK site relative to AK, presumably resulting from longer generation times due to the less optimal conditions for growth at permafrost soils. The most pronounced bacterial taxon shifts observed at OK site, which were somewhat also observed at the AK site, were an increase in abundance of Actinobacteria and decrease in Acidobacteria and Planctomycetes, all representing major phyla in soils, particularly in regards to C-cycling. While shifts in gene pathways due to warming were mild over the 1-year period, our findings show that each site responds differently to warming. OK communities of warmed plots were enriched in genes involved in heat shock response and cellular surface structures, particularly, trans-membrane transporters for glucosides and ferrous iron, whereas their AK counterparts were enriched in metabolic pathways related to labile carbon mobilization and oxidation. By implementing a new contig binning strategy, we recovered large genomic fragments (>500kbp continuous; 2-3Mbp non-continuous) representing several abundant populations (0.2-2% of the total community). These populations appeared to be highly conserved across spatial and environmental gradients at the AK site. Population abundances across samples correspond highly to measured soil characteristics (pH, moisture, SOM, etc.). Our study offers new insights on how soil microbial communities mediate feedback responses of the soil ecosystem to climate change and also addresses basic ecological questions regarding microbial population heterogeneity and biogeography in soils.
    Argonne Soil Metagenomics Meeting, St. Charles, Illinois; 10/2014
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    ABSTRACT: Human gut microbiota plays an important role in the pathogenesis of cirrhosis complications. Although the phylogenetic diversity of intestinal microbiota in patients with liver cirrhosis has been examined in several studies, little is known about their functional composition and structure.
    BMC Genomics 09/2014; 15(1):753. DOI:10.1186/1471-2164-15-753 · 4.04 Impact Factor
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    ABSTRACT: Background/Question/Methods Understanding the responses and the underlying mechanisms of ecological communities to environmental changes is a central issue in ecology. Mean temperature rising on Earth surface represents a pervasive environmental change that is predicted to alter global biodiversity, yet our understanding of the emergent biodiversity impacts is very limited, particularly on taxa-area relationships (TARs) (or spatial scaling of biodiversity), which is one of the few fundamental laws in ecology. Although TARs have been intensively examined, how temperature affects TARs remain elusive remains elusive, particularly in microbial communities. Our main objectives of this study are to understand: (i) Are TARs universally applicable to soil microbial communities at a continental scale? (ii) What are the typical spatial turnover rates for in soil microbial communities? (iii) Whether and how do spatial turnover rates of microbial communities change with temperature as well as plants? To address these questions, we used high throughput sequencing technology to analyze 126 soil samples from six LTER (long-term ecological research) forest locations of different latitudes in North America, whose temperature ranges from -4 to 27°C. Results/Conclusions Our results revealed that the microbial communities in forest soils of six locations across North America exhibited flatter taxa-area relationships (Pearson correlation coefficient r = 0.999) and the slopes (z values) were from 0.068 to 0.085 across six different sites. Although z values from microbial community were relative smaller than the corresponding aboveground plant communities (z = 0.10-0.31), a strong positive correlation was observed between microbial and plant z values (r = 0.782, p = 0.033). Furthermore, both microbial and plant z values significantly increase with the mean annual temperatures across six sampling sites (r = 0.928 for plant community, r = 0.783 for microbial community), indicating that the z values are not constant and the spatial scaling of both plant and microbial communities is temperature dependent. Elucidating temperature-dependent spatial scaling of microbial biodiversity is fundamental to biodiversity preservation, ecosystem restoration and environmental management.
    99th ESA Annual Convention 2014; 08/2014

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