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1.
The phyllosphere of floating macrophytes in paddy soil ecosystems, a unique habitat, may support large microbial communities but remains largely unknown. We took Wolffia australiana as a representative floating plant and investigated its phyllosphere bacterial community and the underlying driving forces of community modulation in paddy soil ecosystems using Illumina HiSeq 2000 platform-based 16S rRNA gene sequence analysis. The results showed that the phyllosphere of W. australiana harbored considerably rich communities of bacteria, with Proteobacteria and Bacteroidetes as the predominant phyla. The core microbiome in the phyllosphere contained genera such as Acidovorax, Asticcacaulis, Methylibium, and Methylophilus. Complexity of the phyllosphere bacterial communities in terms of class number and α-diversity was reduced compared to those in corresponding water and soil. Furthermore, the bacterial communities exhibited structures significantly different from those in water and soil. These findings and the following redundancy analysis (RDA) suggest that species sorting played an important role in the recruitment of bacterial species in the phyllosphere. The compositional structures of the phyllosphere bacterial communities were modulated predominantly by water physicochemical properties, while the initial soil bacterial communities had limited impact. Taken together, the findings from this study reveal the diversity and uniqueness of the phyllosphere bacterial communities associated with the floating macrophytes in paddy soil environments.  相似文献   

2.
Basin-fill aquifers of the Southwestern United States are associated with elevated concentrations of arsenic (As) in groundwater. Many private domestic wells in the Cache Valley Basin, UT, have As concentrations in excess of the U.S. EPA drinking water limit. Thirteen sediment cores were collected from the center of the valley at the depth of the shallow groundwater and were sectioned into layers based on redoxmorphic features. Three of the layers, two from redox transition zones and one from a depletion zone, were used to establish microcosms. Microcosms were treated with groundwater (GW) or groundwater plus glucose (GW+G) to investigate the extent of As reduction in relation to iron (Fe) transformation and characterize the microbial community structure and function by sequencing 16S rRNA and arsenate dissimilatory reductase (arrA) genes. Under the carbon-limited conditions of the GW treatment, As reduction was independent of Fe reduction, despite the abundance of sequences related to Geobacter and Shewanella, genera that include a variety of dissimilatory iron-reducing bacteria. The addition of glucose, an electron donor and carbon source, caused substantial shifts toward domination of the bacterial community by Clostridium-related organisms, and As reduction was correlated with Fe reduction for the sediments from the redox transition zone. The arrA gene sequencing from microcosms at day 54 of incubation showed the presence of 14 unique phylotypes, none of which were related to any previously described arrA gene sequence, suggesting a unique community of dissimilatory arsenate-respiring bacteria in the Cache Valley Basin.  相似文献   

3.
Forty-one bacterial strains isolated from the headbox water of two machines in a Canadian paper mill were associated with the genera Asticcacaulis, Acidovorax, Bacillus, Exiguobacterium, Hydrogenophaga, Pseudomonas, Pseudoxanthomonas, Staphylococcus, Stenotrophomonas based on the sequence of their 16S rRNA genes. The metabolic profile of these strains were determined using Biolog EcoPlate, and the bacteria were divided into four metabolic groups. Metabolic profiles of the bacterial communities colonizing the headbox water of two paper machines was also determined weekly over a 1 year period. The only compound that was not reduced by the bacterial community was 2-hydroxybenzoic acid. Utilization frequency of the other carbon sources in the Biolog EcoPlate ranged from 3 to 100%. The metabolic profiles of the bacterial community did not vary considerably between the two paper machines. However, the metabolic profile varied among the sampling dates.  相似文献   

4.
Aquifers are among the main freshwater sources. The Raigón aquifer is susceptible to contamination, mainly by nitrate and pesticides, such as atrazine, due to increasing agricultural activities in the area. The capacity of indigenous bacteria to attenuate nitrate contamination in different wells of this aquifer was assessed by measuring denitrification rates with either acetate plus succinate or nitrate amendments. Denitrification activity in nitrate-amended assays was significantly higher than in unamended assays, particularly in groundwater from wells where nitrate concentration was 33.5 mg L−1 or lower. Furthermore, groundwater denitrifiers capable of using acetate or succinate as electron donors were isolated, identified by 16S rRNA gene sequencing and evaluated for functional denitrification genes (nirS, nirK and nosZ). Phylogenetic affiliation of 54 isolates showed that all members belonged to nine different genera within the Proteobacteria (Bosea, Ochrobactrum, Azospira, Zoogloea, Acidovorax, Achromobacter, Vogesella, Stenotrophomonas and Pseudomonas). In addition, isolate AR28 that clustered separately from validly described species could potentially belong to a new genus. The majority of the isolates were related to species belonging to previously reported denitrifying genera. However, the phylogeny of the nirS and nosZ genes revealed new sequences of these functional genes. To our knowledge, this is the first isolation and sequencing of the nirS gene from the genus Vogesella, as well as the nosZ gene from the genera Acidovorax and Zoogloea. The results indicated that indigenous bacteria in the Raigón aquifer had the capacity to overcome high nitrate contamination and exhibited functional gene diversity.  相似文献   

5.
Diverse communities of bacteria inhabit plant leaves and roots and those bacteria play a crucial role for plant health and growth. Arabidopsis thaliana is an important model to study plant pathogen interactions, but little is known about its associated bacterial community under natural conditions. We used 454 pyrosequencing to characterize the bacterial communities associated with the roots and the leaves of wild A. thaliana collected at 4 sites; we further compared communities on the outside of the plants with communities in the endophytic compartments. We found that the most heavily sequenced bacteria in A. thaliana associated community are related to culturable species. Proteobacteria, Actinobacteria, and Bacteroidetes are the most abundant phyla in both leaf and root samples. At the genus level, sequences of Massilia and Flavobacterium are prevalent in both samples. Organ (leaf vs root) and habitat (epiphytes vs endophytes) structure the community. In the roots, richness is higher in the epiphytic communities compared to the endophytic compartment (P = 0.024), while the reverse is true for the leaves (P = 0.032). Interestingly, leaf and root endophytic compartments do not differ in richness, diversity and evenness, while they differ in community composition (P = 0.001). The results show that although the communities associated with leaves and roots share many bacterial species, the associated communities differ in structure.  相似文献   

6.
Interactions between bacteria and their host represent a full continuum from pathogenicity to mutualism. From an evolutionary perspective, host-bacteria relationships are no longer considered a two-component system but rather a complex network. In this study, we focused on the relationship between brook charr (Salvelinus fontinalis) and bacterial communities developing on skin mucus. We hypothesized that stressful conditions such as those occurring in aquaculture production induce shifts in the bacterial community of healthy fish, thus allowing pathogens to cause infections. The results showed that fish skin mucus microbiota taxonomical structure is highly specific, its diversity being partly influenced by the surrounding water bacterial community. Two types of taxonomic co-variation patterns emerged across 121 contrasted communities’ samples: one encompassing four genera well known for their probiotic properties, the other harboring five genera mostly associated with pathogen species. The homeostasis of fish bacterial community was extensively disturbed by induction of physiological stress in that both: 1) the abundance of probiotic-like bacteria decreased after stress exposure; and 2) pathogenic bacteria increased following stress exposure. This study provides further insights regarding the role of mutualistic bacteria as a primary host protection barrier.  相似文献   

7.
Barcoded amplicon pyrosequencing was used to generate libraries of partial 16S rRNA genes from two columns designed to simulate in situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) in weathered, contaminated soil. Both columns received a continuous flow of artificial groundwater but one of the columns additionally tested the impact of biostimulation with oxygen and inorganic nutrients on indigenous soil bacterial communities. The penetration of oxygen to previously anoxic regions of the columns resulted in the most significant community changes. PAH-degrading bacteria previously determined by stable-isotope probing (SIP) of the untreated soil generally responded negatively to the treatment conditions, with only members of the Acidovorax and a group of uncharacterized PAH-degrading Gammaproteobacteria maintaining a significant presence in the columns. Additional groups of sequences associated with the Betaproteobacterial family Rhodocyclaceae (including those associated with PAH degradation in other soils), and the Thiobacillus, Thermomonas, and Bradyrhizobium genera were also present in high abundance in the biostimulated column. Similar community responses were previously observed during biostimulated ex situ treatment of the same soil in aerobic, slurry-phase bioreactors. While the low relative abundance of many SIP-determined groups in the column libraries may be a reflection of the slow removal of PAHs in that system, the similar response of known PAH degraders in a higher-rate bioreactor system suggests that alternative PAH-degrading bacteria, unidentified by SIP of the untreated soil, may also be enriched in engineered systems.  相似文献   

8.
Microbial regrowth in drinking water distribution systems (DWDS) is a major concern in the water supply industry. Detailed knowledge of the microbial community in DWDS will be of great importance for assessing the microbiological risks of drinking water. The spatial heterogeneity of microbial community structures in the bulk waters of a large real DWDS was investigated using 16S rRNA clone library analysis. The results indicate that high residual chlorine in drinking water could not control microbial regrowth in DWDS. The bacterial communities in the bulk waters were spatially heterogenic, mainly composed of Alphaproteobacteria and Betaproteobacteria (or Cyanobacteria). Microorganisms from the genera Acinetobacter, Sphingomonas and Gemella were detected, implying there is microbiological risk from drinking water. This work provides new insight into microbial ecology in DWDS.  相似文献   

9.
To determine if there is a core microbial community in the microbial populations of different wastewater treatment plants (WWTPs) and to investigate the effects of wastewater characteristics, operational parameters, and geographic locations on microbial communities, activated sludge samples were collected from 14 wastewater treatment systems located in 4 cities in China. High-throughput pyrosequencing was used to examine the 16S rRNA genes of bacteria in the wastewater treatment systems. Our results showed that there were 60 genera of bacterial populations commonly shared by all 14 samples, including Ferruginibacter, Prosthecobacter, Zoogloea, Subdivision 3 genera incertae sedis, Gp4, Gp6, etc., indicating that there is a core microbial community in the microbial populations of WWTPs at different geographic locations. The canonical correspondence analysis (CCA) results showed that the bacterial community variance correlated most strongly with water temperature, conductivity, pH, and dissolved oxygen (DO) content. Variance partitioning analyses suggested that wastewater characteristics had the greatest contribution to the bacterial community variance, explaining 25.7% of the variance of bacterial communities independently, followed by operational parameters (23.9%) and geographic location (14.7%). Results of this study provided insights into the bacterial community structure and diversity in geographically distributed WWTPs and discerned the relationships between bacterial community and environmental variables in WWTPs.  相似文献   

10.
High-throughput sequencing was used for comparative analysis of microbial communities of the water and mat from the Hoito-Gol mesothermal mineral sulfide spring (Eastern Sayan Mountains, Buryat Republic). Activity of microbial communities was determined. While both spring biotopes were dominated by members of three bacterial phyla—Proteobacteria, Bacteroidetes, and Firmicutes—they differed drastically in the composition of predominant phylotypes (at the genus level). In the water, the organisms widespread in aquatic environments were predominant, mostly aerobic chemoorganotrophs of the genera Acinetobacter, Pedobacter, and Flavobacterium. In the microbial mat, the organisms actively involved in the sulfur cycle predominated, including sulfur-reducing bacteria Sulfurospirillum, sulfate-reducing deltaproteobacteria, sulfuroxidizing chemoautotrophic bacteria, anoxygenic phototrophic bacteria of the phyla Chloroflexi and Chlorobi, as well as purple bacteria belonging to the α-, ß-, and γ-Proteobacteria. Microbial mats of the spring exhibited higher phylogenetic diversity compared to high-temperature mats containing photosynthetic microorganisms.  相似文献   

11.
Biological activated carbon (BAC) filters are commonly used in the world for improvement of drinking water quality. The indigenous microbiota in BAC filters can play a crucial role in reduction or biotransformation of contaminants. Molecular analysis can enhance our understanding of ecological functions of the microbial communities in drinking water BAC filters. In this study, three laboratory-scale drinking water BAC filters receiving influents of different types were constructed. Differences of bacterial communities in the three BAC filters were characterized using 454 pyrosequencing analysis. Pyrosequencing analysis illustrated the usefulness in elucidating the bacterial community structure in drinking water biofilter. High bacterial diversity in granular activated carbon (GAC) samples from each BAC biofilter was observed. Proteobacteria was the largest bacterial phylum in each GAC sample, with a marked shift of the proportions of Alpha-, Beta-, and Gammaproteobacteria. The levels of dissolved organic carbon and ammonia nitrogen in the influents could affect the bacterial diversity and community composition in the BAC biofilters. This work might add some new insights into microbial community and its influential factors in drinking water biofilters.  相似文献   

12.
The Nycteribiidae are obligate blood-sucking Diptera (Hippoboscoidea) flies that parasitize bats. Depending on species, these wingless flies exhibit either high specialism or generalism toward their hosts, which may in turn have important consequences in terms of their associated microbial community structure. Bats have been hypothesized to be reservoirs of numerous infectious agents, some of which have recently emerged in human populations. Thus, bat flies may be important in the epidemiology and transmission of some of these bat-borne infectious diseases, acting either directly as arthropod vectors or indirectly by shaping pathogen communities among bat populations. In addition, bat flies commonly have associations with heritable bacterial endosymbionts that inhabit insect cells and depend on maternal transmission through egg cytoplasm to ensure their transmission. Some of these heritable bacteria are likely obligate mutualists required to support bat fly development, but others are facultative symbionts with unknown effects. Here, we present bacterial community profiles that were obtained from seven bat fly species, representing five genera, parasitizing bats from the Malagasy region. The observed bacterial diversity includes Rickettsia, Wolbachia, and several Arsenophonus-like organisms, as well as other members of the Enterobacteriales and a widespread association of Bartonella bacteria from bat flies of all five genera. Using the well-described host specificity of these flies and data on community structure from selected bacterial taxa with either vertical or horizontal transmission, we show that host/vector specificity and transmission mode are important drivers of bacterial community structure.  相似文献   

13.
不同生长季节黑果枸杞的根际细菌群落结构   总被引:1,自引:0,他引:1  
王飞  杨晓东  李岩 《微生物学报》2019,59(3):533-545
【目的】黑果枸杞是一种耐盐植物,是我国西北干旱区盐渍土改良的优良植物物种,其根际土壤细菌群落结构在不同生长时期的变化特征尚不清楚。【方法】本研究采用Illumina MiSeq高通量测序研究了黑果枸杞3个生长阶段的根际土壤细菌群落结构的动态变化。【结果】所有样品中共获得317467条序列,对应于7028个细菌/古细菌OTUs。根际土壤细菌群落的α多样性显著高于非根际土壤。衰老期根际细菌的多样性和丰富度明显低于营养生长期和花/果期。变形菌门和酸杆菌门的相对丰度随生长时期的演变而逐渐降低,而蓝细菌门则相反。厚壁菌门的丰度在衰老期明显高于营养生长期和花/果期。优势属的组成也随生长期的演变而改变,营养生长期、花/果期、衰老期的优势属数量分别为17、16、4,且组成也具有差异。相似性分析表明营养生长期和花/果期的根际细菌群落具有很高的相似性,衰老期根际细菌群落组成与生长期和花/果期具有很高差异,然而与非根际土壤的群落结构具有较高的相似性。【结论】根际土壤细菌群落多样性和组成随生长期的改变而表现出明显的动态变异性,表明黑果枸杞生长时期对根际土壤细菌群落结构具有重要的影响。  相似文献   

14.
鄱阳湖湖泊细菌群落组成及结构——以松门山为例   总被引:8,自引:0,他引:8  
于2011年5月在鄱阳湖——松门山湖区采集底泥与表层水样,分别提取了表层水体浮游和底泥微生物基因组DNA,利用454高通量测序技术对细菌的16S rRNA基因进行了序列测定,分析了湖泊底泥细菌、水体浮游细菌群落结构特征。结果显示:底泥细菌OTUs(Operational Taxonomic Units)为1454,表层水体浮游细菌OTUs为269;底泥细菌群落比表层水体更加多样化,底泥细菌的物种数大大多于表层水体。同时,底泥细菌群落与表层浮游细菌群落结构存在显著差异。物种分类显示鄱阳湖底泥细菌种类隶属于20门,228属,其中优势种群为δ-变形菌纲(Deltaproteobacteria)、β-变形菌纲(Betaproteobacteria)和疣微菌门(Verrucomicrobia);表层水体浮游细菌隶属于13门116属,优势种群为β-变形菌纲、拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria)。结果进一步揭示,无论是浮游细菌群落还是沉积物细菌群落,优势细菌种群的基因型多样性更高。  相似文献   

15.
Two aerobic, lab-scale, slurry-phase bioreactors were used to examine the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil and the associated bacterial communities. The two bioreactors were operated under semi-continuous (draw-and-fill) conditions at a residence time of 35 days, but one was fed weekly and the other monthly. Most of the quantified PAHs, including high-molecular-weight compounds, were removed to a greater extent in the weekly-fed bioreactor, which achieved total PAH removal of 76%. Molecular analyses, including pyrosequencing of 16S rRNA genes, revealed significant shifts in the soil bacterial communities after introduction to the bioreactors and differences in the abundance and types of bacteria in each of the bioreactors. The weekly-fed bioreactor displayed a more stable bacterial community with gradual changes over time, whereas the monthly-fed bioreactor community was less consistent and may have been more strongly influenced by the influx of untreated soil during feeding. Phylogenetic groups containing known PAH-degrading bacteria previously identified through stable-isotope probing of the untreated soil were differentially affected by bioreactor conditions. Sequences from members of the Acidovorax and Sphingomonas genera, as well as the uncultivated “Pyrene Group 2” were abundant in the bioreactors. However, the relative abundances of sequences from the Pseudomonas, Sphingobium, and Pseudoxanthomonas genera, as well as from a group of unclassified anthracene degraders, were much lower in the bioreactors compared to the untreated soil.  相似文献   

16.
Deconstruction of the cellulose in plant cell walls is critical for carbon flow through ecosystems and for the production of sustainable cellulosic biofuels. Our understanding of cellulose deconstruction is largely limited to the study of microbes in isolation, but in nature, this process is driven by microbes within complex communities. In Neotropical forests, microbes in leaf-cutter ant refuse dumps are important for carbon turnover. These dumps consist of decaying plant material and a diverse bacterial community, as shown here by electron microscopy. To study the portion of the community capable of cellulose degradation, we performed enrichments on cellulose using material from five Atta colombica refuse dumps. The ability of enriched communities to degrade cellulose varied significantly across refuse dumps. 16S rRNA gene amplicon sequencing of enriched samples identified that the community structure correlated with refuse dump and with degradation ability. Overall, samples were dominated by Bacteroidetes, Gammaproteobacteria, and Betaproteobacteria. Half of abundant operational taxonomic units (OTUs) across samples were classified within genera containing known cellulose degraders, including Acidovorax, the most abundant OTU detected across samples, which was positively correlated with cellulolytic ability. A representative Acidovorax strain was isolated, but did not grow on cellulose alone. Phenotypic and compositional analyses of enrichment cultures, such as those presented here, help link community composition with cellulolytic ability and provide insight into the complexity of community-based cellulose degradation.  相似文献   

17.
Bacterial diversity of reed (Phragmites australis) periphyton communities of Kelemen-szék and Nagy-Vadas (two Hungarian soda ponds) was investigated using molecular cloning and cultivation-based techniques. The majority of the 80 Kelemen-szék and 72 Nagy-Vadas bacterial isolates proved to be moderately halophilic and alkaliphilic. A great proportion of the isolates showed phosphatase and urease activity, utilized aesculin, citrate and certain biopolymers (e.g., gelatine and tween 80). Partial 16S rDNA sequence analysis of 33 Kelemen-szék and 20 Nagy-Vadas ARDRA group representatives showed Gram-positive (Nesterenkonia, Cellulomonas, Dietzia, Bacillus and Planococcus) dominance at both sampling sites. Species of the genera Acidovorax, Hydrogenophaga (β-Proteobacteria) and Flavobacterium, Sphingobacterium (Bacteroidetes) were represented only from Kelemen-szék. Altogether 16 isolates showed low sequence similarity with yet described bacteria and may represent novel taxa. Screening of the 16S rRNA gene libraries of 129 Kelemen-szék and 158 Nagy-Vadas clones resulted in 30 and 28 different ARDRA groups, respectively. Sequence analysis revealed a Gram-negative (Rheinheimera, Aquimonas, Cellvibrio, Flavobacterium and Sphingobacterium) dominated phylogenetic diversity. A high number of the clones were affiliated with uncultured bacterial clones described from diverse environmental samples.  相似文献   

18.
新疆断裂带泉水中细菌群落结构的PCR-DGGE分析   总被引:4,自引:0,他引:4  
乌鲁木齐10号泉起源于天山山脉博格达峰,地下径流于地震断裂带,泉水中硫化氢、甲烷等地球化学元素迁移活跃,为 揭示水文地球化学变化对地震断裂带泉水细菌群落结构的影响,本研究对该泉水样品定期采样,以微孔滤膜收集菌体,使用SDS-酶解法提取总DNA,对细菌16S rDNA V 3区进行PCR-DGGE分析并对条带测序,条带的光密度信息与监测的地球化学指标进行典型相关分析(CCA)。结果表明B16(Uncultured bacterium)和ε-变性菌纲 (epsilon proteobacterium)与氟含量成正相关;黄杆菌B1 (Flavobacterium)、绿脓假单胞菌(Pseudomonas aeruginosa)、B10(Uncultured bacterium)和腐生性葡萄球菌(Staphylococcus saprophyticus)与硫化物呈正相关;硫微螺菌(Thiomicrospira arctica) 、黄杆菌B3(Flavobacterium)及阿尔莱葡萄球菌(Staphylococcus arlettae)与氢气呈正相关。断裂带泉水细菌能够对地层深处渗透出的地球化学元素产生灵敏的应答。  相似文献   

19.
Sediment microbial communities are important for seagrass growth and carbon cycling, however relatively few studies have addressed the composition of prokaryotic communities in seagrass bed sediments. Selective media were used enumerate culturable anaerobic bacteria associated with the roots of the seagrass, Halodule wrightii, the fresh to brackish water plant, Vallisneria americana, and the respective vegetated and unvegetated sediments. H. wrightii roots and sediments had high numbers of sulfate-reducing bacteria whereas iron-reducing bacteria appeared to have a more significant role in V. americana roots and sediments. Numbers of glucose-utilizing but not acetate-utilizing iron reducers were higher on the roots of both plants relative to the vegetated sediments indicating a difference within the iron reducing bacterial community. H. wrightii roots had lower glucose-utilizing iron reducers, and higher acetogenic bacteria than did V. americana roots suggesting different aquatic plants support different anaerobic microbial communities. Sulfur-disproportionating and sulfide-oxidizing bacteria were also cultured from the roots and sediments. These results provide evidence of the potential importance of sulfur cycle bacteria, in addition to sulfate-reducing bacteria, in seagrass bed sediments.  相似文献   

20.
Drinking water reservoir plays a vital role in the security of urban water supply, yet little is known about microbial community diversity harbored in the sediment of this oligotrophic freshwater environmental ecosystem. In the present study, integrating community level physiological profiles (CLPPs), nested polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and clone sequence technologies, we examined the sediment urease and protease activities, bacterial community functional diversity, genetic diversity of bacterial and fungal communities in sediments from six sampling sites of Zhou cun drinking water reservoir, eastern China. The results showed that sediment urease activity was markedly distinct along the sites, ranged from 2.48 to 11.81 mg NH3-N/(g·24h). The highest average well color development (AWCD) was found in site C, indicating the highest metabolic activity of heterotrophic bacterial community. Principal component analysis (PCA) revealed tremendous differences in the functional (metabolic) diversity patterns of the sediment bacterial communities from different sites. Meanwhile, DGGE fingerprints also indicated spatial changes of genetic diversity of sediment bacterial and fungal communities. The sequence BLAST analysis of all the sediment samples found that Comamonas sp. was the dominant bacterial species harbored in site A. Alternaria alternate, Allomyces macrogynus and Rhizophydium sp. were most commonly detected fungal species in sediments of the Zhou cun drinking water reservoir. The results from this work provide new insights about the heterogeneity of sediment microbial community metabolic activity and genetic diversity in the oligotrophic drinking water reservoir.  相似文献   

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