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1.
Tauber T Berta B Székely AJ Gyarmati I Kékesi K Márialigeti K Tóth EM 《Acta microbiologica et immunologica Hungarica》2007,54(1):47-55
The aim of the present work was to compare the microbial communities of a mesophilic and a thermophilic pilot scale anaerobe sludge digester. For studying the communities cultivation independent chemotaxonomical methods (RQ and PLFA analyses) and T-RFLP were applied. Microbial communities of the mesophilic and thermophilic pilot digesters showed considerable differences, both concerning the species present, and their abundance. A Methanosarcina sp. dominated the thermophilic, while a Methanosaeta sp. the mesophilic digester among Archaea. Species diversity of Bacteria was reduced in the thermophilic digester. Based on the quinone patterns in both digesters the dominance of sulphate reducing respiratory bacteria could be detected. The PLFA profiles of the digester communities were similar though in minor components characteristic differences were shown. Level of branched chain fatty acids is slightly lower in the thermophilic digester that reports less Gram positive bacteria. The relative ratio of fatty acids characteristic to Enterobacteriaceae, Bacteroidetes and Clostridia shows differences between the two digesters: their importance generally decreased under thermophilic conditions. The sulphate reducer marker (15:1 and 17:1) fatty acids are present in low quantity in both digesters. 相似文献
2.
Diverse microbial communities inhabiting ferromanganese deposits in Lechuguilla and Spider Caves 总被引:3,自引:0,他引:3
Northup DE Barns SM Yu LE Spilde MN Schelble RT Dano KE Crossey LJ Connolly CA Boston PJ Natvig DO Dahm CN 《Environmental microbiology》2003,5(11):1071-1086
Lechuguilla Cave is an ancient, deep, oligotrophic subterranean environment that contains an abundance of low-density ferromanganese deposits, the origin of which is uncertain. To assess the possibility that biotic factors may be involved in the production of these deposits and to investigate the nature of the microbial community in these materials, we carried out culture-independent, small subunit ribosomal RNA (SSU rRNA) sequence-based studies from two sites and from manganese and iron enrichment cultures inoculated with ferromanganese deposits from Lechuguilla and Spider Caves. Sequence analysis showed the presence of some organisms whose closest relatives are known iron- and manganese-oxidizing/reducing bacteria, including Hyphomicrobium, Pedomicrobium, Leptospirillum, Stenotrophomonas and Pantoea. The dominant clone types in one site grouped with mesophilic Archaea in both the Crenarchaeota and Euryarchaeota. The second site was dominated almost entirely by lactobacilli. Other clone sequences were most closely related to those of nitrite-oxidizing bacteria, nitrogen-fixing bacteria, actinomycetes and beta- and gamma-Proteobacteria. Geochemical analyses showed a fourfold enrichment of oxidized iron and manganese from bedrock to darkest ferromanganese deposits. These data support our hypothesis that microorganisms may contribute to the formation of manganese and iron oxide-rich deposits and a diverse microbial community is present in these unusual secondary mineral formations. 相似文献
3.
Characterization of microbial communities of biofilters by phospholipid fatty acid analysis and rRNA targeted oligonucleotide probes 总被引:1,自引:0,他引:1
The microbial community of a biofilter for waste gas treatment of an animal rendering plant was characterized by the analyses of the phospholipid fatty acids (PLFAs) of the filter material. For these analyses five samples of one filter were taken in intervals between one and two months. The main components of the PLFA profiles were straight chain saturated, monounsaturated and cyclopropyl fatty acids. Terminally branched and 10-methyl branched fatty acids were present in minor amounts. The structure and succession of the microbial community was interpreted by the presence and quantitative changes of diagnostic fatty acids. The stability of diagnostic fatty acids in relation to varying incubation parameters was tested for a number of bacterial isolates from biofilters representing different phylogenetic branches. For two samples, the data from the PLFA-analyses were compared with data obtained by hybridization with fluorescently labeled, rRNA-targeted oligonucleotide probes specific for the alpha-, beta- and gamma-subclass of the Proteobacteria, the Actinobacteria (Firmicutes with high G+C content) and the Firmicutes with low G+C content. These data indicated a dominating number of Proteobacteria (54% and 35% of DAPI-stained cells), in which the gamma-Proteobacteria represented the main fraction. Actinobacteria were detected in minor amounts, the number of Firmicutes with low G+C content was near the detection limit of the method. About half of the cells detected with a probe specific for Bacteria did not hybridize with the probes specific for the alpha-, beta- and gamma subclass of the Proteobacteria and the two subgroups of the Firmicutes. The results of both methods, the fluorescence in situ hybridization (FISH) and the PLFA analyses corresponded well and were best suited to confirm and complement each other. 相似文献
4.
To control the environmentally detrimental impact of acid rock drainage, two different countermeasures, layers of acid-buffering
materials and sodium dodecyl sulphate addition, were tested for their efficiency in laboratory percolation experiments. In
the experiment with a layer of calcium bentonite, only the iron output was reduced. The experiments with layers of concrete
grains demonstrated a decrease of the microbial activity as well as a precipitation of heavy-metal ions, whereas the cell
numbers did not decrease. Furthermore, finely grained concrete (1–5 mm) formed a water-tight hardpan (self-sealing layer).
In the experiment with 1 mM sodium dodecyl sulphate, all the microorganisms were killed and hence metal sulphide dissolution
was stopped. With 0.1 mM sodium dodecyl sulphate only a short, transient inhibition of leaching was achieved. The bacteria
remained alive.
Received: 16 February 1998 / Accepted: 23 February 1998 相似文献
5.
Community analysis of a full-scale anaerobic bioreactor treating paper mill wastewater 总被引:4,自引:0,他引:4
Roest K Heilig HG Smidt H de Vos WM Stams AJ Akkermans AD 《Systematic and applied microbiology》2005,28(2):175-185
To get insight into the microbial community of an Upflow Anaerobic Sludge Blanket reactor treating paper mill wastewater, conventional microbiological methods were combined with 16S rRNA gene analyses. Particular attention was paid to microorganisms able to degrade propionate or butyrate in the presence or absence of sulphate. Serial enrichment dilutions allowed estimating the number of microorganisms per ml sludge that could use butyrate with or without sulphate (10(5)), propionate without sulphate (10(6)), or propionate and sulphate (10(8)). Quantitative RNA dot-blot hybridisation indicated that Archaea were two-times more abundant in the microbial community of anaerobic sludge than Bacteria. The microbial community composition was further characterised by 16S rRNA-gene-targeted Denaturing Gradient Gel Electrophoresis (DGGE) fingerprinting, and via cloning and sequencing of dominant amplicons from the bacterial and archaeal patterns. Most of the nearly full length (approximately 1.45 kb) bacterial 16S rRNA gene sequences showed less than 97% similarity to sequences present in public databases, in contrast to the archaeal clones (approximately. 1.3 kb) that were highly similar to known sequences. While Methanosaeta was found as the most abundant genus, also Crenarchaeote-relatives were identified. The microbial community was relatively stable over a period of 3 years (samples taken in July 1999, May 2001, March 2002 and June 2002) as indicated by the high similarity index calculated from DGGE profiles (81.9+/-2.7% for Bacteria and 75.1+/-3.1% for Archaea). 16S rRNA gene sequence analysis indicated the presence of unknown and yet uncultured microorganisms, but also showed that known sulphate-reducing bacteria and syntrophic fatty acid-oxidising microorganisms dominated the enrichments. 相似文献
6.
Ferris MJ Magnuson TS Fagg JA Thar R Kühl M Sheehan KB Henson JM 《Environmental microbiology》2003,5(10):954-960
Our objective in this study was to characterize prokaryotic sulphide production within the oxygenic, predominantly eukaryotic algal mat in an acidic stream, Nymph Creek, in Yellowstone National Park (YNP). We used microsensors to examine fluctuations in H2S and O2 concentrations over time through the vertical aspect of the approximately 3 mm mat in a 46-48 degrees C region of the creek. We also used analyses of PCR-amplified 16S rRNA gene sequences obtained from denaturing gradient gels, and PCR-amplified sequences of a functional gene associated with microbial sulphate respiration (dsrA) to characterize the bacterial community in the same region of the mat. During midday, photosynthesis rates were high within the first 500 micro m interval of the mat and high oxygen concentrations (600% air saturation) penetrated deeply (>1800 micro m) into the mat. During early evening and night, oxygen concentrations within the first 1100 micro m of the mat decreased over time from 60% air saturation (a.s) to 12% a.s. A precipitous decline in oxygen concentration occurred at a depth of 1100 micro m in all night measurements and anoxic conditions were present below 1200 micro m. Within this anoxic region, sulphide concentrations increased from nearly 0 micro M at 1200 micro m depth to 100 micro M at 2400 micro m depth. Enrichment cultures inoculated with Nymph Creek mat organisms also produced H2S. Sequence analyses of 16S rRNA and dsrA genes indicated the presence of at least five bacterial genera including species involved in dissimilative sulphate or sulphur reduction. 相似文献
7.
S J Macnaughton M R Cormier T L Jenkins G A Davis D C White 《Journal of industrial microbiology & biotechnology》1999,22(2):80-87
Exposure to airborne biocontaminants may result in a multitude of health effects and is related to a pronounced increase in
adult-onset asthma. Established culture-based procedures for quantifying microbial biomass from airborne environments have
severe limitations. Assay of the phospholipid fatty acid (PLFA) components of airborne microorganisms provides a quantitative
method to define biomass, community composition and nutritional/physiological activity of the microbial community. By collecting
airborne particulate matter from a high volume via filtration, we collected sufficient biomass for quantitative PLFA analysis.
Comparing high (filtration) and low (impaction) volume air sampling techniques at 26 locations within the Eastern United States,
we determined that PLFA analysis provided a viable alternative to the established but flawed culture-based techniques for
measuring airborne microbial biomass and community composition. Compared to the PLFA analysis, the culture techniques underestimated
the actual viable airborne biomass present by between one to three orders of magnitude. A case study of a manufacturing plant
at which there had been complaints regarding the indoor air quality is presented. Phospholipid fatty acid characterization
of the biomass enabled contamination point source determination. In comparison with samples taken outdoors, increases in the
relative proportion of trans PLFA, reflecting shifts in the physiological status of viable airborne Gram-negative bacteria, were detected in the indoor
air samples at a majority of sampling sites.
Received 29 September 1998/ Accepted in revised form 8 January 1999 相似文献
8.
In vitro demonstration of anaerobic oxidation of methane coupled to sulphate reduction in sediment from a marine gas hydrate area 总被引:3,自引:0,他引:3
Anaerobic oxidation of methane (AOM) and sulphate reduction were examined in sediment samples from a marine gas hydrate area (Hydrate Ridge, NE Pacific). The sediment contained high numbers of microbial consortia consisting of organisms that affiliate with methanogenic archaea and with sulphate-reducing bacteria. Sediment samples incubated under strictly anoxic conditions in defined mineral medium (salinity as in seawater) produced sulphide from sulphate if methane was added as the sole organic substrate. No sulphide production occurred in control experiments without methane. Methane-dependent sulphide production was fastest between 4 degree C and 16 degree C, the average rate with 0.1 MPa (approximately 1 atm) methane being 2.5 micro mol sulphide day(-1) and (g dry mass sediment)(-1). An increase of the methane pressure to 1.1 MPa (approximately 11 atm) resulted in a four to fivefold increase of the sulphide production rate. Quantitative measurements using a special anoxic incubation device without gas phase revealed continuous consumption of dissolved methane (from initially 3.2 to 0.7 mM) with simultaneous production of sulphide at a molar ratio of nearly 1:1. To test the response of the indigenous community to possible intermediates of AOM, molecular hydrogen, formate, acetate or methanol were added in the absence of methane; however, sulphide production from sulphate with any of these compounds was much slower than with methane. In the presence of methane, such additions neither stimulated nor inhibited sulphate reduction. Hence, the experiments did not provide evidence for one of these compounds acting as a free extracellular intermediate (intercellular shuttle) during AOM by the presently investigated consortia. 相似文献
9.
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
10.
11.
The contributions of “new” carbon coming from plants with the C4-type of photosynthesis (maize) and “old” carbon from soil organic matter (SOM) formed under C3 vegetation as carbon sources for microorganisms was determined. Soil samples were taken from the plots of field experiments on Chernozem and Phaeozem. The values of δ13C were determined in evolved CO2, SOM, total microbial biomass (Cmic), and phospholipid fatty acids (PLFA), assuming that the PLFA markers for certain taxonomic groups of microorganisms enriched in C4 carbon indicated a more significant role of these microorganisms in the transformation of root exudates and plant residues. Carbon pools were arranged in the following order by the degree of their enrichment with “new” C: SOM < Cmic < CO2. Consequently, the “new” carbon proved to be a more preferable substrate for microbial growth than the “old” one. The share of C4 in the markers varied from 18 to 60% (on average 38%) in Phaeozem and from 15 to 40% in Chernozem (on average 28%). The groups of microorganisms in Phaeozem were arranged in the following order by the degree of their enrichment with “new” carbon: protozoa < saprotrophic fungi < actinomycetes < gram-positive bacteria < gramnegative bacteria < mycorrhizal fungi. In Chernozem, the contribution of C4 to the carbon composition of PLFA did not differ significantly for various groups of microorganisms. The C4 content within the PLFA markers of fungi and gram-negative bacteria did not demonstrate any crucial contribution of these groups of organisms to the transformation of “new” C. The long-term C3–C4 transition probably results in formation of a broad range of carbon pools similar in their C4 content but different in resistance to mineralization; therefore, gram-positive bacteria could assimilate C4 from resistant C pools. The low content of “new” carbon in the PLFA markers of fungi may be explained by a considerable portion of dormant forms. 相似文献
12.
Variation in Microbial Community Structure in Two Boreal Peatlands as Determined by Analysis of Phospholipid Fatty Acid Profiles 总被引:9,自引:4,他引:5
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Analyses of phospholipid fatty acids (PLFAs) were used to assess variation in community structure and total microbial biomass in two boreal peatlands in Sweden. The total PLFA concentration in peat ranged from 0.16 to 7.0 nmol g of wet peat(sup-1) (median, 0.70 nmol g of wet peat(sup-1)). Principal-component analysis of PLFA data revealed that the degree of depth-related variation in PLFA composition was high among peatland habitats, with general differences between wet sites, with water tables within a few centimeters of the moss surface, and dry sites, with water tables >10 cm below the moss surface. However, variation in PLFA composition over the growing season was negligible. In the principal-component analyses, most PLFAs were determined to be parts of clusters of covarying fatty acids, suggesting that they originated in the same functional groups of microorganisms. Major clusters were formed by monounsaturated (typical of gram-negative eubacteria), terminally branched (gram-positive or anaerobic gram-negative eubacteria), methyl-branched and branched unsaturated (sulfate-reducing bacteria and/or actinomycetes), (omega)8 monounsaturated (methane-oxidizing bacteria), and polyunsaturated (eucaryotes) PLFAs. Within the clusters, PLFAs had rather distinct concentration-depth distributions. For example, PLFAs from sulfate-reducing bacteria and/or actinomycetes and those from methane-oxidizing bacteria had maximum concentrations slightly below and at the average water table depth, respectively. 相似文献
13.
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
14.
Subsurface Microbial Diversity in Deep-Granitic-Fracture Water in Colorado 总被引:1,自引:1,他引:0
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Jason W. Sahl Raleigh Schmidt Elizabeth D. Swanner Kevin W. Mandernack Alexis S. Templeton Thomas L. Kieft Richard L. Smith William E. Sanford Robert L. Callaghan Jeffry B. Mitton John R. Spear 《Applied microbiology》2008,74(1):143-152
A microbial community analysis using 16S rRNA gene sequencing was performed on borehole water and a granite rock core from Henderson Mine, a >1,000-meter-deep molybdenum mine near Empire, CO. Chemical analysis of borehole water at two separate depths (1,044 m and 1,004 m below the mine entrance) suggests that a sharp chemical gradient exists, likely from the mixing of two distinct subsurface fluids, one metal rich and one relatively dilute; this has created unique niches for microorganisms. The microbial community analyzed from filtered, oxic borehole water indicated an abundance of sequences from iron-oxidizing bacteria (Gallionella spp.) and was compared to the community from the same borehole after 2 weeks of being plugged with an expandable packer. Statistical analyses with UniFrac revealed a significant shift in community structure following the addition of the packer. Phospholipid fatty acid (PLFA) analysis suggested that Nitrosomonadales dominated the oxic borehole, while PLFAs indicative of anaerobic bacteria were most abundant in the samples from the plugged borehole. Microbial sequences were represented primarily by Firmicutes, Proteobacteria, and a lineage of sequences which did not group with any identified bacterial division; phylogenetic analyses confirmed the presence of a novel candidate division. This “Henderson candidate division” dominated the clone libraries from the dilute anoxic fluids. Sequences obtained from the granitic rock core (1,740 m below the surface) were represented by the divisions Proteobacteria (primarily the family Ralstoniaceae) and Firmicutes. Sequences grouping within Ralstoniaceae were also found in the clone libraries from metal-rich fluids yet were absent in more dilute fluids. Lineage-specific comparisons, combined with phylogenetic statistical analyses, show that geochemical variance has an important effect on microbial community structure in deep, subsurface systems. 相似文献
15.
Molecular phylogenetic diversity of the microbial community associated with a high-temperature petroleum reservoir at an offshore oilfield 总被引:1,自引:0,他引:1
The microbial community and its diversity in production water from a high-temperature, water-flooded petroleum reservoir of an offshore oilfield in China were characterized by 16S rRNA gene sequence analysis. The bacterial and archaeal 16S rRNA gene clone libraries were constructed from the community DNA and, using sequence analysis, 388 bacterial and 220 archaeal randomly selected clones were clustered with 60 and 28 phylotypes, respectively. The results showed that the 16S rRNA genes of bacterial clones belonged to the divisions Firmicutes, Thermotogae, Nitrospirae and Proteobacteria, whereas the archaeal library was dominated by methanogen-like rRNA genes (Methanothermobacter, Methanobacter, Methanobrevibacter and Methanococcus), with a lower percentage of clones belonging to Thermoprotei. Thermophilic microorganisms were found in the production water, as well as mesophilic microorganisms such as Pseudomonas and Acinetobacter-like clones. The thermophilic microorganisms may be common inhabitants of geothermally heated specialized subsurface environments, which have been isolated previously from a number of high-temperature petroleum reservoirs worldwide. The mesophilic microorganisms were probably introduced into the reservoir as it was being exploited. The results of this work provide further insight into the composition of microbial communities of high-temperature petroleum reservoirs at offshore oilfields. 相似文献
16.
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
17.
The prevalence of viable thermophilic bacteria and actinomycetes and mesophilic fungi was examined in 145 samples from 110 domestic humidifiers. A total of 72 and 43% of furnace and console humidifier samples, respectively, contained viable thermophilic bacteria, whereas 60 and 72% of these samples produced mesophilic fungal growth. Thermophilic actinomycetes were recovered from seven humidifier samples. Efforts to detect thermophilic actinomycete antigens in 15 humidifier fluid samples were not successful. Antifoulants added to humidifier fluid reservoirs had no apparent effect on microbial frequency. Airborne microbial recoveries did not reflect patterns of humidifier contamination with respect to either kinds or numbers of microorganisms in 20 homes in which volumetric air samples were obtained during humidifier operation. 相似文献
18.
Shifts in archaeal communities associated with lithological and geochemical variations in subsurface Cretaceous rock 总被引:1,自引:0,他引:1
Takai K Mormile MR McKinley JP Brockman FJ Holben WE Kovacik WP Fredrickson JK 《Environmental microbiology》2003,5(4):309-320
Subsurface microbial community structure in relation to geochemical gradients and lithology was investigated using a combination of molecular phylogenetic and geochemical analyses. Discreet groundwater and substratum samples were obtained from depths ranging from 182 to 190 m beneath the surface at approximately 10-cm intervals using a multilevel sampler (MLS) that straddled Cretaceous shale and sandstone formations at a site in the southern San Juan Basin in New Mexico. DNA and RNA were extracted directly from quartzite sand substratum loaded into individual cells of the MLS and colonized in situ. Polymerase chain reaction (PCR)-mediated T-RFLP analysis of archaeal rRNA genes (rDNA) in conjunction with partial sequencing analysis of archaeal rDNA libraries and quantitative RNA hybridization with oligonucleotide probes were used to probe community structure and function. Although total microbial populations remained relatively constant over the entire depth interval sampled, significant shifts in archaeal populations, predominantly methanogens, were observed. These shifts coincided with the geochemical transition from relatively high methane (26 mM), low sulphate (< 3 mg l(-1)) conditions in the region adjacent to the organic matter-rich shale to relatively low-methane (< 0.5 mM), high-sulphate (48 mg l(-1)) conditions in the organic-poor sandstone beneath the shale. These results indicated that active, phylogenetically diverse archaeal communities were present in the subsurface Cretaceous rock environment at this site and that major archaeal clades shifted dramatically over scales of tens of centimetres, corresponding to changes in the lithology and geochemical gradients. 相似文献
19.
In a field experiment we have examined the effect of long-term grassland management regimes (viz., intensive versus extensive) and dominant plant species (viz., Arrhenatherum elatius, Holcus lanatus and Dactylis glomerata) on soil organic carbon (SOC) build up, soil microbial communities using biomarker phospholipid fatty acids (PLFA), and the relationship between SOC and PLFAs of major groups of microorganisms (viz., bacteria, fungi, and actinomycetes). The results have revealed that changes in SOC were not significantly affected by the intensity of management or by the plant species composition or by their interaction. The amount of PLFA of each microbial group was affected weakly by management regime and plant species, but the canonical variance analysis (CVA), based on individual PLFA values, demonstrated significant (P<0.05) effects of management regime and plant species on the composition of microbial community. Positive and significant (P<0.01) relationships were observed between PLFA of bacteria (R2=0.47), fungi (R2=0.33), actinomycetes (R2=0.71) and total microbial PLFA (R2=0.53) and SOC content. 相似文献
20.
Ambient outdoor concentrations and size distributions of airborne microbial particles were measured approximately weekly for 2 years in a Washington, D.C., suburban area. The study objective was to characterize microbial air quality in the vicinity of a proposed sewage sludge composting facility. During the study, 379 samples were taken at 17 stations, using Andersen microbial samplers. Concentration ranges (in viable particles per cubic meter) were as follows: airborne mesophilic fungi, 0 to 7,220 with a geometric mean of 273; thermophilic fungi, 0 to 193 with a median of 2.1; Aspergillus fumigatus, 0 to 71 with a median of 1.0; aerobic bacteria, 4.2 to 1,640 with a geometric mean of 79; and fecal streptococci, 0 to 5.7 with a median of 0. No fecal coliforms were recovered. The potentially respirable fraction (less than 8 microns) averaged 34% for total bacteria, 56% for mesophilic fungi, 91% for thermophilic fungi, and 95% for A. fumigatus. The specific sampling location was not a major factor affecting microbial particle concentrations or size distributions. Conversely, the time of year was an important determinant of viable particle concentrations for all groups of microorganisms studied. The highest concentrations were observed in summer and fall, with significantly lower levels detected in winter. In general, the microbial data did not correlate with other variables, including weather conditions, measured in this study. 相似文献