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1.
Xinqing Zhao Liuyan Yang Can Chen Lin Xiao Lijuan Jiang Zhe Ma Haowei Zhu Zhenyang Yu Daqiang Yin 《Frontiers of Biology in China》2008,3(3):293-299
In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was applied to analyze the microbial communities in lake
sediments from Lake Xuanwu, Lake Mochou in Nanjing and Lake Taihu in Wuxi. Sediment samples from seven locations in three
lakes were collected and their genomic DNAs were extracted. The DNA yields of the sediments of Lake Xuanwu and Lake Mochou
were high (10 μg/g), while that of sediments in Lake Taihu was relatively low. After DNA purification, the 16S rDNA genes
(V3 to V5 region) were amplified and the amplified DNA fragments were separated by parallel DGGE. The DGGE profiles showed
that there were five common bands in all the lake sediment samples indicating that there were similarities among the populations
of microorganisms in all the lake sediments. The DGGE profiles of Lake Xuanwu and Lake Mochou were similar and about 20 types
of microorganisms were identified in the sediment samples of both lakes. These results suggest that the sediment samples of
these two city lakes (Xuanwu, Mochou) have similar microbial communities. However, the DGGE profiles of sediment samples in
Lake Taihu were significantly different from these two lakes. Furthermore, the DGGE profiles of sediment samples in different
locations in Lake Taihu were also different, suggesting that the microbial communities in Lake Taihu are more diversified
than those in Lake Xuanwu and Lake Mochou. The differences in microbial diversity may be caused by the different environmental
conditions, such as redox potential, pH, and the concentrations of organic matters. Seven major bands of 16S rDNA genes fragments
from the DGGE profiles of sediment samples were further re-amplified and sequenced. The results of sequencing analysis indicate
that five sequences shared 99%–100% homology with known sequences (Bacillus and Brevibacillus, uncultured bacteria), while the other two sequences shared 93%–96% homology with known sequences (Acinetobacter, and Bacillus). The study shows that the PCR-DGGE technique combined with sequence analysis is a feasible and efficient method for the
determination of microbial communities in sediment samples.
__________
Translated from Acta Ecologica Sinica, 2006, 26(11): 3610–3616 [译自: 生态学报] 相似文献
2.
Bacterial community along a historic lake sediment core of Ardley Island, west Antarctica 总被引:6,自引:0,他引:6
The bacterial community in a historic lake sediment core of Ardley Island, Antarctica, spanning approximately 1,600 years, was investigated by molecular approaches targeting the 16S rRNA gene fragments. The cell number in each 1 cm layer of the sediment core was deduced through semi-quantification of the 16S rRNA gene copies by quantitative competitive PCR (QC-PCR). It was found that the total bacterial numbers remained relatively stable along the entire 59 cm sediment core. Denaturing Gradient Gel Electrophoresis (DGGE) analysis and sequencing of PCR-amplified 16S rRNA gene fragments were performed to analyze the bacterial diversity over the entire column. Principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into three groups. There were obvious bacterial community shift among groups of 1–20 cm, 21–46 cm and 46–59 cm. Diversity indices indicated that the bacterial community in the 21–46 cm depth showed the highest species diversity and uniformity. The main bacterial groups in the sediments fell into 4 major lineages of the gram-negative bacteria: the α, γ and δ subdivision of Proteobacteria, the Cytophaga-Flavobacteria-Bacteroides, and some unknown sequences. The gram-positive bacteria Gemmatimonadetes, Firmicutes and Actinobacteria were also detected. The results demonstrated the presence of highly diverse bacterial community population in the Antarctic lake sediment core. And the possible influence of climate and penguin population change on the bacterial community shift along the sediment core was discussed.Shengkang Li and Xiang Xiao contributed equally to this paper 相似文献
3.
Sediment Microbial Community Structure and Mercury Methylation in Mercury-Polluted Clear Lake, California 总被引:6,自引:3,他引:3
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Spatial and temporal variations in sediment microbial community structure in a eutrophic lake polluted with inorganic mercury were identified using polar lipid fatty acid (PLFA) analysis. Microbial community structure was strongly related to mercury methylation potential, sediment organic carbon content, and lake location. Pore water sulfate, total mercury concentrations, and organic matter C/N ratios showed no relationships with microbial community structure. Seasonal changes and changes potentially attributable to temperature regulation of bacterial membranes were detectable but were less important influences on sediment PLFA composition than were differences due to lake sampling location. Analysis of biomarker PLFAs characteristic of Desulfobacter and Desulfovibrio groups of sulfate-reducing bacteria suggests that Desulfobacter-like organisms are important mercury methylators in the sediments, especially in the Lower Arm of Clear Lake. 相似文献
4.
Aims: The purpose of this study was to discuss how the environmental inputs and anthropogenic activities impact bacterial communities in the sediments of a shallow, eutrophic and temperate freshwater lake. Methods and Results: Sediment cores were collected from Lake Dongping, located in Taian, Shandong, China. All samples were processed within 4 h of collection. Total nitrogen, total phosphorus (TP), total organic carbon, ammonium nitrogen and nitrate nitrogen content of samples were measured by Kjeldahl determination, sulphuric acid–perchloric acid digestion and molybdenum blue colorimetry, potassium dichromate titration, Nessler’s reagent colorimetric and the phenol disulphonic acid colorimetric method, respectively. Seasonal and temporal diversity of sediment bacterial communities at six stations in Lake Dongping were investigated using molecular approaches (terminal restriction fragment length polymorphism and 16S rDNA clone libraries). Noticeable seasonal and temporal variations were observed in bacterial diversity and composition at all six stations. Sediment bacterial communities in Lake Dongping belonged to 16 phyla: Proteobacteria (including α‐Proteobacteria, β‐Proteobacteria, δ‐Proteobacteria, ε‐Proteobacteria, γ‐Proteobacteria), Acidobacteria, Planctomycetes, Bacteroidetes, Firmicutes, Verrucomicrobia, Nitrospira, Chloroflexi, Gemmatimonadetes, Chlorobi, Cyanobacteria, Deferribacteres, Actinobacteria, OP8, Spirochaetes and OP11. Members of β‐, δ‐ and γ‐Proteobacterial sequences were predominant in 11 of 12 clone libraries derived from sediment samples. Sediment samples collected at stations 1 and 4 in July had the greatest bacterial diversity while those collected at station 2 in October had the least diversity. TP concentration was significantly correlated with the distribution of bacterial communities. Conclusions: Our results suggested that different environmental nutrient inputs contribute to seasonal and temporal variations of chemical features and bacterial communities in sediments of Lake Dongping. TP concentration was significantly correlated with the distribution of bacterial communities. Significance and Impact of the Study: This study has an important implication for the optimization of integrated ecosystem assessment of shallow temperate freshwater lake and provides interesting information for the subsequent of the ecosystem. 相似文献
5.
Microbial Communities in High and Low Recharge Environments: Implications for Microbial Transport in the Vadose Zone 总被引:2,自引:0,他引:2
D.L. Balkwill E.M. Murphy D.M. Fair D.B. Ringelberg D.C. White 《Microbial ecology》1998,35(2):156-171
Abstract
Microbial communities along vertical transects in the unsaturated zone were evaluated at five sites in the Pasco Basin, in
southeastern Washington State. Sites with contrasting recharge rates were chosen to maximize or minimize the potential for
microbial transport. Pore water ages along the vertical transects were established using natural chloride tracers, and ranged
from modern to either ∼15,000 yBP (years before present) or ∼30,000 yBP at the two low-recharge sites. Unsaturated flow processes
were short-circuited by preferential flow at two of the three high-recharge sites, resulting in rapid movement of water through
the vertical transects. Microbial numbers and biomass, based on plate counts, and phospholipid fatty acid (PLFA) concentrations
decreased with depth at all sites. The majority (55–90%) of the culturable chemoheterotrophs recovered from most samples were
streptomycete bacteria. 16S rRNA gene sequence and MIDI analyses indicated that 75% of the remaining isolates were Gram-positive
bacteria (most likely species of Arthrobacter and Bacillus) 25% were Gram-negative bacteria (probably members of several genera in the alpha- and gamma-Proteobacteria). Comparison of microbial communities at low-recharge sites vs. high-recharge sites, where preferential flow occurs, revealed
several differences that might be attributed to vertical transport of microbial cells at the high-recharge sites. Plate counts
and PLFA analyses indicated that the proportion of streptomycetes, which were abundant at the surface but present in the subsurface
as spores, decreased, or remained constant, with depth at the low-recharge sites, but increased with depth at the high-recharge
sites. PLFA analyses also indicated that Gram-negative bacteria displayed increased nutrient stress with depth at the high-recharge
sites characterized by preferential flow, but not at the low recharge site. This may be a result of advective transport of
microbes to depths where it was difficult for them to compete effectively with the established community. Moreover, PLFA community
structure profiles fluctuated considerably with depth at the low-recharge sites, but not at the high-recharge sites. This
might be expected if transport were distributing the microbial community along the vertical profile at the high-recharge sites.
In contrast to the high-recharge sites at which preferential flow occurs, filtration likely prevented vertical transport of
microorganisms at the high-recharge site that was characterized by unsaturated flow.
Received: 6 November 1996; Accepted: 9 May 1997 相似文献
6.
Srinivasa Varadhan A Khodadoust AP Brenner RC 《Journal of industrial microbiology & biotechnology》2011,38(10):1691-1707
Reductive dehalogenation of polychlorinated biphenyls (PCBs) by indigenous dehalorespiring microorganisms in contaminated
sediments may be enhanced via biostimulation by supplying hydrogen generated through the anaerobic corrosion of elemental
iron added to the sediment. In this study, the effect of periodic amendment of sediment with various dosages of iron on the
microbial community present in sediment was investigated using phospholipid fatty acid analysis (PLFA) over a period of 18 months.
Three PCB-contaminated sediments (two freshwater lake sediments and one marine sediment) were used. Signature biomarker analysis
of the microbial community present in all three sediments revealed the enrichment of Dehalococcoides species, the population of which was sustained for a longer period of time when the sediment microcosms were amended with
the lower dosage of iron (0.01 g iron per g dry sediment) every 6 months as compared to the blank system (without iron). Lower
microbial stress levels were reported for the system periodically amended with 0.01 g of iron per g dry sediment every 6 months,
thus reducing the competition from other hydrogen-utilizing microorganisms like methanogens, iron reducers, and sulfate reducers.
The concentration of hydrogen in the system was found to be an important factor influencing the shift in microbial communities
in all sediments with time. Periodic amendment of sediment with larger dosages of iron every 3 months resulted in the early
prevalence of Geobacteraceae and sulfate-reducing bacteria followed by methanogens. An average pH of 8.4 (range of 8.2–8.6) and an average hydrogen concentration
of 0.75% (range of 0.3–1.2%) observed between 6 and 15 months of the study were found to be conducive to sustaining the population
of Dehalococcoides species in the three sediments amended with 0.01 g iron per g dry sediment. Biostimulation of indigenous PCB dechlorinators
by the periodic amendment of contaminated sediments with low dosages of iron metal may therefore be an effective technology
for remediation of PCB-contaminated sediments. 相似文献
7.
To understand the composition and structure of microbial communities in acid mineral bioleaching systems, the molecular diversity
of 16S rDNA genes was examined using a PCR-based cloning approach. A total of 31 Operational Taxonomic Units (OTUs) were obtained
from the four samples taken from four different bioleaching sites in Yinshan lead–zinc mine and Dongxiang copper mine in Jiangxi
Province, China. The percentages of overlapping OTUs between sites ranged from 22.2 to 50.0%. Phylogenetic analysis revealed
that the bacteria present at the four bioleaching sites fell into six divisions, α-Proteobacteria (1.1%), β-Proteobacteria (2.3%), γ-Proteobacteria (30.8%), Firmicutes (15.4%), Actinobacteria (0.3%) and Nitrospira (50.1%). Organisms of genera Leptospirillum, Acidithiobacillus, and Sulfobacillus, which were in Nitrospira, γ-Proteobacteria, and Firmicutes divisions, respectively, were the most dominant. The results of principal component analysis based on the six phylogenetic
divisions and biogeochemical data indicated that the microbial community structure of a site was directly related to the biogeochemical
characteristic of that site. It follows therefore that sites with similar biogeochemical characteristics were comprised of
similar microbial community structures. The results in our study also suggest that the elements copper and arsenic appear
to be the key factors affecting the compositions and structures of microbial community in the four bioleaching sites.
Zhiguo He, Shengmu Xiao, Xuehui Xie are equally contributed to this work. 相似文献
8.
Park SJ Park BJ Jung MY Kim SJ Chae JC Roh Y Forwick M Yoon HI Rhee SK 《Microbial ecology》2011,62(3):537-548
Increases in global temperatures have been shown to enhance glacier melting in the Arctic region. Here, we have evaluated
the effects of meltwater runoff on the microbial communities of coastal marine sediment located along a transect of Temelfjorden,
in Svalbard. As close to the glacier front, the sediment properties were clearly influenced by deglaciation. Denaturing gradient
gel electrophoresis profiles showed that the sediment microbial communities of the stations of glacier front (stations 188–178)
were distinguishable from that of outer fjord region (station 176). Canonical correspondence analysis indicated that total
carbon and calcium carbonate in sediment and chlorophyll a in bottom water were key factors driving the change of microbial
communities. Analysis of 16S rRNA gene clone libraries suggested that microbial diversity was higher within the glacier–proximal
zone (station 188) directly affected by the runoffs than in the outer fjord region. While the crenarchaeotal group I.1a dominated
at station 176 (62%), Marine Benthic Group-B and other Crenarchaeota groups were proportionally abundant. With regard to the
bacterial community, alpha-Proteobacteria and Flavobacteria lineages prevailed (60%) at station 188, whereas delta-Proteobacteria (largely sulfate-reducers) predominated (32%) at station 176. Considering no clone sequences related to sulfate-reducers,
station 188 may be more oxic compared to station 176. The distance-wise compositional variation in the microbial communities
is attributable to their adaptations to the sediment environments which are differentially affected by melting glaciers. 相似文献
9.
The deposition of mine tailings generated from 125 years of sulfidic ore mining resulted in the enrichment of Coeur d'Alene
River (CdAR) sediments with significant amounts of toxic heavy metals. A review of literature suggests that microbial populations
play a pivotal role in the biogeochemical cycling of elements in such mining-impacted sedimentary environments. To assess
the indigenous microbial communities associated with metal-enriched sediments of the CdAR, high-density 16S microarray (PhyloChip)
and clone libraries specific to bacteria (16S rRNA), ammonia oxidizers (amoA), and methanogens (mcrA) were analyzed. PhyloChip analysis provided a comprehensive assessment of bacterial populations and detected the largest
number of phylotypes in Proteobacteria followed by Firmicutes and Actinobacteria. Furthermore, PhyloChip and clone libraries displayed considerable metabolic diversity in indigenous microbial populations
by capturing several chemolithotrophic groups such as ammonia oxidizers, iron-reducers and -oxidizers, methanogens, and sulfate-reducers
in the CdAR sediments. Twenty-two phylotypes detected on PhyloChip could not be classified even at phylum level thus suggesting
the presence of novel microbial populations in the CdAR sediments. Clone libraries demonstrated very limited diversity of
ammonia oxidizers and methanogens in the CdAR sediments as evidenced by the fact that only Nitrosospira- and Methanosarcina-related phylotypes were retrieved in amoA and mcrA clone libraries, respectively. 相似文献
10.
Diatom analysis of surface sediments and two sediment cores from different sedimentation areas of a small closed lake was
undertaken with the aim of acquiring knowledge on the dependence of the distribution of diatom assemblages on lake bathymetry.
Lake Juusa was selected for the study because we have for this lake a large data set about the lithological composition of
sediments and macrofossil and cladoceran records for the Holocene. A high carbonate content (20–60%) in the sediment sequence
indicates high carbonacity and relatively stable pH values during the Holocene. On the basis of comprehensive analysis, abrupt
water-level fluctuations and changes in the trophic status were established. Results of this study showed that the fluctuations
of the water-level were the leading factor determining the habitats of diatom assemblages in the lake. In the surface sediment
samples planktonic species such as Cyclotella spp., Stephanodiscus spp. and Aulacoseira spp. had a depth optimum at 3–4 m and the most abundant periphytic taxa were distributed mostly at depths shallower than
3.5 m. The same regularity was established in sediment cores where a good correlation between planktonic species and lake
water depth was found in sediments accumulated at water depths >4 m. Lake Juusa appears to be a proper site for detailed environmental
reconstructions over the Holocene, and the results will give us a good opportunity to analyse the history of water-level fluctuations
in other small Estonian lakes.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Handling editor: K. Martens 相似文献
11.
Microbial Diversity in Water and Sediment of Lake Chaka, an Athalassohaline Lake in Northwestern China 总被引:5,自引:1,他引:4
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Hongchen Jiang Hailiang Dong Gengxin Zhang Bingsong Yu Leah R. Chapman Matthew W. Fields 《Applied microbiology》2006,72(6):3832-3845
We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 108 cells/g at the water-sediment interface to 107 cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community. 相似文献
12.
Physiological Status and Community Composition of Microbial Mats of the Ebro Delta, Spain, by Signature Lipid Biomarkers 总被引:3,自引:0,他引:3
Navarrete A Peacock A Macnaughton SJ Urmeneta J Mas-Castellà J White DC Guerrero R 《Microbial ecology》2000,39(1):92-99
Abstract
Physiological status of microbial mats of the Ebro Delta (Tarragona, Spain) based on the extraction of lipids considered ``signature
lipid biomarkers' (SLB) from the cell membranes and walls of microorganisms has been analyzed. Data from a day–night cycle
show significant differences in viable cells countings (PLFA cells counts) ranging from 1.5 × 1010 to 5.0 × 1010 cells g−1 of sediment. Minimum values were observed at 18:00 and 6:00, when physicochemical conditions change drastically. The diversity
of the microbial community was assessed by GC/MS analysis of phospholipid fatty acids (PLFA). The ratio of PLFA, representative
of Gram-negative bacteria, comprises 47.8% of the total PLFA of the microbial mat community. The remaining PLFA was representative
of Gram-positive (10.0%), anaerobic (5.7%), and eukaryotic microorganisms (5.7%), and other common lipids. Two different approaches
were used as a comparative study to assess the physiological status of the microbial mats. Two parameters (cyclopropane fatty
acids/ω7c monoenoic fatty acids, and measurement of the trans/cis monoenoic PLFA ratio) showed a minimum at midnight, suggesting the highest microbial activity. Higher values were observed
at 18:00 and 6:00, coinciding with lower PLFA cell counts.
Received: 14 May 1999; Accepted: 6 September 1999; Online Publication: 24 March 2000 相似文献
13.
Microbial Diversity in Sediments Collected from the Deepest Cold-Seep Area, the Japan Trench 总被引:16,自引:0,他引:16
The Japan Trench land slope at a depth of 6,400 m is the deepest cold-seep environment with Calyptogena communities. Sediment samples from inside and beside the Calyptogena communities were collected, and the microbial diversity in the sediment samples was studied by molecular phylogenetic techniques.
From DNA extracted directly from the sediment samples, 16S rDNAs were amplified by the polymerase chain reaction method. The
sequences of the amplified 16S rDNAs selected by restriction fragment length polymorphism analysis were determined and compared
with sequences in DNA databases. The results showed that 33 different bacterial 16S rDNA sequences from the two samples analyzed
fell into similar phylogenetic categories, the α-, γ-, δ-, and ɛ-subdivisions of Proteobacteria, Cytophaga, and gram-positive
bacteria; some of the 16S rDNA sequences were common to both samples. δ- and ɛ-Proteobacteria-related sequences were abundant
in both sediments. These sequences are mostly related to sulfate-reducing or sulfur-reducing bacteria and epibionts, respectively.
Eight different archaeal 16S rDNA sequences were cloned from the sediments. The majority of the archaeal 16S rDNA sequences
clustered in Crenarchaeota and showed high similarities to marine group I archaeal rDNA. A Methanococcoides burtonii–related sequence obtained from the sediment clustered in the Euryarchaeota indicating that M. burtonii–related strains in the area of Calyptogena communities may contribute to production of methane in this environment. From these results, we propose a possible model
of sulfur circulation within the microbial community and that of Calyptogena clams in the cold-seep environment.
Received June 15, 1998; accepted November 10, 1998. 相似文献
14.
Microbial community structure and biomass estimates of a methanogenic Antarctic Lake ecosystem as determined by phospholipid analyses 总被引:3,自引:0,他引:3
Phospholipid analyses were performed on water column particulate and sediment samples from Ace Lake, a meromictic lake in the Vestfold Hills, Antarctica, to estimate the viable microbial biomass and community structure in the lake. In the water column, methanogenic bacterial phospholipids were present below 17 m in depth at concentrations which converted to a biomass of between 1 and 7×108 cells/liter. Methanogenic biomass in the sediment ranged from 17.7×109 cells/g dry weight of sediment at the surface to 0.1×109 cells/g dry weight at 2 m in depth. This relatively high methanogenic biomass implies that current microbial degradation of organic carbon in Ace Lake sediments may occur at extremely slow rates. Total microbial biomass increased from 4.4×108 cells/ liter at 2 m in depth to 19.4×108 cells/liter at 23 m, near the bottom of the water column. Total nonarchaebacterial biomass decreased from 4.2 ×109 cells/g dry weight in the surface sediment (1/4 the biomass of methanogens) to 0.06×108 cells/g dry weight at 2 m in depth in the sediment. Phospholipid fatty acid profiles showed that microeukaryotes were the major microbial group present in the oxylimnion of the lake, while bacteria dominated the lower, anoxic zone. Sulfate-reducing bacteria (SRB) comprised 25% of the microbial population at 23 m in depth in the water column particulates and were present in the surface sediment but to a lesser extent. Biomass estimates and community structure of the Ace Lake eco-system are discussed in relation to previously measured metabolic rates for this and other antarctic and temperate ecosystems. This is the first instance, to our knowledge, in which the viable biomass of methanogenic and SRB have been estimated for an antarctic microbial community. 相似文献
15.
Invasive species poses a threat to the world’s oceans. Alien sponges account for the majority of introduced marine species
in the isolated Hawaiian reef ecosystems. In this study, cultivation-dependent and cultivation-independent techniques were
applied to investigate microbial consortia associated with the alien Hawaiian marine sponge Suberites zeteki. Its microbial communities were diverse with representatives of Actinobacteria, Firmicutes, α- and γ-Proteobacteria, Bacteroidetes, Chlamydiae, Planctomycetes, and Cyanobacteria. Specifically, the genus Chlamydia was identified for the first time from marine sponges, and two genera (Streptomyces and Rhodococcus) were added to the short list of culturable actinobacteria from sponges. Culturable microbial communities were dominated
by Bacillus species (63%) and contained actinobacterial species closely affiliated with those from habitats other than marine sponges.
Cyanobacterial clones were clustered with free-living cyanobacteria from water column and other environmental samples; they
show no affiliation with other sponge-derived cyanobacteria. The low sequence similarity of Planctomycetes, Chlamydiae, and α-Proteobacteria clones to other previously described sequences suggested that S. zeteki may contain new lineages of these bacterial groups. The microbial diversity of S. zeteki was different from that of other studied marine sponges. This is the first report on microbial communities of alien marine
invertebrate species. For the first time, it provides an insight into microbial structure within alien marine sponges in the
Hawaiian marine ecosystems. 相似文献
16.
Klára Kaštovská Marek Stibal Marie Šabacká Barbora Černá Hana Šantrůčková Josef Elster 《Polar Biology》2007,30(3):277-287
Biological and physico-chemical characteristics of subglacial sediments were studied in Svalbard. Sediment from close proglacial
and supraglacial environments was used for a comparison. Viable bacteria, cyanobacteria and microalgae were detected in subglacial
sediments from two polythermal glaciers using epifluorescence microscopy and phospholipid fatty acid (PLFA) analyses. The
subglacial samples were generally of higher pH values, coarser texture and lower water content, organic matter, organic carbon,
and nitrogen compared to proglacial and supraglacial sediments). Bacterial counts of 1.6 × 107 cells mg− 1 OM (organic matter) were found. Cyanobacteria and algae were also of low abundance [4.2 cells mg− 1 DW (dry weight)]. Cyanobacteria comprised the major proportion of the autophotothrophic assemblages of subglacial soils.
Deglaciated soils were similar to subglacial sediment in physico-chemical properties and microbial structure and numbers,
unlike soil from vegetated sites or cryoconite sediment. In subglacial and deglaciated soil, relatively low diversity of microorganisms
and low substrate availability was detected by PLFA analyses. Good accordance in microbial community structure assessments
between epifluorescence microscopy and PLFA analyses was found. Our results suggest that the subglacial microbial populations
can be divided into two groups: autochthonous microorganims (chemoheterotrophic bacteria) and allochthonous that retain the
ability to proliferate and give rise to active population when conditions become favorable.
Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at . 相似文献
17.
G. Martins I. Henriques D. C. Ribeiro A. Correia P. L. E. Bodelier J. V. Cruz 《Geomicrobiology journal》2013,30(8):704-715
In the Azores, the advanced trophic state of the lakes requires a fast intervention to achieve the good ecological status prescribed by the Water Framework Directive. Despite the considerable effort made to describe the phytoplankton growing on the water column, the lack of information regarding the microbial processes in sediments is still high. Thus, for the successful implementation of internal management actions, the present work explored the relationships between geochemical profiles and dominant members of the bacterial community in sediments from eutrophic Azorean lakes. Lake Azul geochemical profiles were quite homogeneous for all parameters, while in lake Furnas the total iron profile presented a peak below the aerobic layer. For lake Verde, the concentrations of all studied parameters (20 ± 2% loss-on-ignition; 2.10 ± 0.08 mg g?1 total phosphorus; 1.31 ± 0.50 mg g?1 total nitrogen; 8.06 ± 0.13 mg g?1 total iron) in the uppermost sediment layer were approximately two times higher than the ones in sediments from other lakes, decreasing with sediment depth. The higher amounts of phosphorus and organic matter in lake Verde suggested a higher internal contribution of phosphorus to eutrophication. The dominant members of the sediment bacterial community, investigated by denaturing gradient gel electrophoresis, were mostly affiliated to Proteobacteria phylum (Alpha-, Delta-, and Gamma-subclasses), group Bacteroidetes/Chlorobi and phylum Chloroflexi. The Cyanobacteria phylum was solely detected in sediments from lake Verde and lake Furnas that presented the highest amounts of nitrogen and phosphorus both in the water column and sediments, while the other phyla were detected in sediments from the three studied lakes. In conclusion, management measurers to achieve the good ecological status until 2015 should be distinct for the different lakes taking into account the relative magnitude of the nutrient sources and the bacterial diversity in sediments. 相似文献
18.
This study provides some results about microbial activity in salt marsh sediments. Microbial activity was determined by profiling
extracellular enzyme activities in three Tagus estuary marshes and in two sediments horizons: surface layer (0–2 cm) and depth
(8–10 cm). Five enzymatic activities were examined (β-glucosidase, cellulase, alkaline phosphatase, potential nitrification and nitrate reductase). All extracellular enzymatic
activities were highest in the surface layer and decreased with depth. β-glucosidase and alkaline phosphatase prevailed both in surface sediments (1150 and 1200 ηmol h−1 g−1, respectively) and in deeper sediments (150 and 200 ηmol h−1 g−1, respectively). Microbial activities differed significantly between salt marshes. The marsh location in the estuary seemed
to contribute to these differences: marshes located in the proximity of urbanised and industrial areas had higher microbial
activities. 相似文献
19.
Links between Geographic Location, Environmental Factors, and Microbial Community Composition in Sediments of the Eastern Mediterranean Sea 总被引:6,自引:0,他引:6
The bacterial community composition of marine surface sediments originating from various regions of the Eastern Mediterranean Sea (12 sampling sites) was compared by parallel use of three fingerprinting methods: analysis of 16S rRNA gene fragment heterogeneity by denaturing gradient electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP), and analysis of phospholipid-linked fatty acid composition (PLFA). Sampling sites were located at variable depths (30–2860 m; water column depth above the sediments) and the sediments differed greatly also in their degree of petroleum contamination (0.4–18 μg g−1), organic carbon (0.38–1.5%), and chlorophyll a content (0.01–7.7 μg g−1). Despite a high degree of correlation between the three different community fingerprint methods, some major differences were observed. DGGE banding patterns showed a significant separation of sediment communities from the northern, more productive waters of the Thermaikos Gulf and the oligotrophic waters of the Cretan, S. Ionian, and Levantine Sea. T-RFLP analysis clearly separated the communities of deep sediments (>1494 m depth) from their shallow (<617 m) counterparts. PLFA analysis grouped a shallow station from the productive waters of the north with the deep oligotrophic sediments from the Ionian and Levantine Sea, with low concentrations of PLFAs, and hence low microbial biomass, as the common denominator. The degree of petroleum contamination was not significantly correlated to the apparent composition of the microbial communities for any of the three methods, whereas organic carbon content and sediment chlorophyll a were important in this regard. 相似文献
20.
Cultivable Bacterial Community from South China Sea Sponge as Revealed by DGGE Fingerprinting and 16S rDNA Phylogenetic Analysis 总被引:2,自引:0,他引:2
The cultivable bacterial communities associated with four South China Sea sponges—Stelletta tenuis, Halichondria rugosa, Dysidea avara, and Craniella australiensis in mixed cultures—were investigated by microbial community DNA-based DGGE fingerprinting and 16S rDNA phylogenetic analysis.
Diverse bacteria such as α-, γ-, δ-Proteobacteria, Bacteroidetes, and Firmicutes were cultured, some of which were previously uncultivable bacteria, potential novel strains with less than 95% similarity
to their closest relatives and sponge symbionts growing only in the medium with the addition of sponge extract. According
to 16S rDNA BLAST analysis, most of the bacteria were cultured from sponge for the first time, although similar phyla of bacteria
have been previously recognized. The selective pressure of sponge extract on the cultured bacterial species was suggested,
although the effect of sponge extract on bacterial community in high nutrient medium is not significant. Although α- and γ-Proteobacteria appeared to form the majority of the dominant cultivable bacterial communities of the four sponges, the composition of the
cultivable bacterial community in the mixed culture was different, depending on the medium and sponge species. Greater bacterial
diversity was observed in media C and CS for Stelletta tenuis, in media F and FS for Halichondria rugosa and Craniella australiensis. S. tenuis was found to have the highest cultivable bacterial diversity including α-, γ-, δ-Proteobacteria, Bacteroidetes, and Firmicutes, followed by sponge Dysidea avara without δ-Proteobacteria, sponge Halichondria rugosa with only α-, γ-Proteobacteria and Bacteroidetes, and sponge C. australiensis with only α-, γ-Proteobacteria and Firmicutes. Based on this study, by the strategy of mixed cultivation integrated with microbial community DNA-based DGGE fingerprinting
and phylogenetic analysis, the cultivable bacterial community of sponge could be revealed effectively. 相似文献