共查询到20条相似文献,搜索用时 31 毫秒
1.
Freeman SA Sierra-Alvarez R Altinbas M Hollingsworth J Stams AJ Smidt H 《Biodegradation》2008,19(2):161-177
The microbial communities established in mesophilic and thermophilic expanded granular sludge bed reactors operated with sulfate
as the electron acceptor were analyzed using 16S rRNA targeted molecular methods, including denaturing gradient gel electrophoresis,
cloning, and phylogenetic analysis. Bacterial and archaeal communities were examined over 450 days of operation treating ethanol
(thermophilic reactor) or ethanol and later a simulated semiconductor manufacturing wastewater containing citrate, isopropanol,
and polyethylene glycol 300 (mesophilic reactor), with and without the addition of copper(II). Analysis, of PCR-amplified
16S rRNA gene fragments using denaturing gradient gel electrophoresis revealed a defined shift in microbial diversity in both
reactors following a change in substrate composition (mesophilic reactor) and in temperature of operation from 30°C to 55°C
(thermophilic reactor). The addition of copper(II) to the influent of both reactors did not noticeably affect the composition
of the bacterial or archaeal communities, which is in agreement with the very low soluble copper concentrations (3–310 μg l−1) present in the reactor contents as a consequence of extensive precipitation of copper with biogenic sulfides. Furthermore,
clone library analysis confirmed the phylogenetic diversity of sulfate-reducing consortia in mesophilic and thermophilic sulfidogenic
reactors operated with simple substrates. 相似文献
2.
Masaru Akiyama Satoru Shimizu Toshiaki Sakai Seiichiro Ioka Yoji Ishijima Takeshi Naganuma 《Limnology》2011,12(1):1-9
Spatiotemporal variations in microbial gene abundances were investigated to identify potential zones of methanotroph and methanogen
biomass in a peat bog in Sarobetsu-genya wetland. The abundances of the bacterial and archaeal 16S rRNA genes, pmoA, and mcrA were 107–109, 107–108, 104–106, and 104–107 copies g−1 dry peat, respectively. Correlation analysis based on microbial gene abundances and environmental factors showed that the
spatiotemporal distributions of the abundances of the four microbial genes in peat layers were similar. The mcrA abundance showed a significant negative correlation with the dissolved organic carbon content and a significant positive
correlation with the peat temperature. The pmoA abundance was not detectable during the spring thaw when the lowest peat temperature at a depth of 50 cm was recorded. At
a depth of 200 cm, the peat temperature exceeded 6°C throughout the year, and the mcrA abundance exceeded 104 copies g−1 dry peat. These results indicate that the seasonal microbial activity related to methane should be evaluated in not only
the shallow but also the deep peat layers in order to elucidate the methane dynamics in boreal wetlands. 相似文献
3.
Microbial community structure in anaerobic co-digestion of grass silage and cow manure in a laboratory continuously stirred tank reactor 总被引:1,自引:0,他引:1
Hong Wang Katariina Tolvanen Annimari Lehtomäki Jaakko Puhakka Jukka Rintala 《Biodegradation》2010,21(1):135-146
The impacts of feeding ratio and loading rate on the microbial community during co-digestion of grass silage with cow manure
in an anaerobic laboratory continuously stirred tank reactor were investigated by 16S rRNA gene-based fingerprints. The microbial
community remained stable when the reactor was fed with cow manure alone and with up to 20% of grass silage in feedstock at
an organic loading rate (OLR) of 2 kg VS m−3 day−1. Large changes in the bacterial community were observed when the loading ratio of grass was increased to 40%, while there
was little change in the archaeal community. During the increase in OLR from 2 to 4 kg VS m−3 day−1 the bacterial community structure showed few differences, whereas Archaea was undetectable. Sequencing of the major DGGE bands indicated that the phylum Bacteriodetes predominated in the bacterial community. Two unclassified bacteria with high abundance survived throughout the operation
of the reactor. 相似文献
4.
David van der Ha Sven Hoefman Pascal Boeckx Willy Verstraete Nico Boon 《Applied microbiology and biotechnology》2010,87(6):2355-2363
Effluents of anaerobic digesters are an underestimated source of greenhouse gases, as they are often saturated with methane.
A post-treatment with methane-oxidizing bacterial consortia could mitigate diffuse emissions at such sites. Semi-continuously
fed stirred reactors were used as model systems to characterize the influence of the key parameters on the activity of these
mixed methanotrophic communities. The addition of 140 mg L−1 NH4+–N had no significant influence on the activity nor did a temperature increase from 28°C to 35°C. On the other hand, addition
of 0.64 mg L−1 of copper(II) increased the methane removal rate by a factor of 1.5 to 1.7 since the activity of particulate methane monooxygenase
was enhanced. The influence of different concentrations of NaCl was also tested, as effluents of anaerobic digesters often
contain salt levels up to 10 g NaCl L−1. At a concentration of 11 g NaCl L−1, almost no methane-oxidizing activity was observed in the reactors without copper addition. Yet, reactors with copper addition
exhibited a sustained activity in the presence of NaCl. A colorimetric test based on naphthalene oxidation showed that soluble
methane monooxygenase was inhibited by copper, suggesting that the particulate methane monooxygenase was the active enzyme
and thus more salt resistant. The results obtained demonstrate that the treatment of methane-saturated effluents, even those
with increased ammonium (up to 140 mg L−1 NH4+–N) and salt levels, can be mitigated by implementation of methane-oxidizing microbial consortia. 相似文献
5.
Kengo Sasaki Masahiko Morita Shin-ichi Hirano Daisuke Sasaki Naoya Ohmura Yasuo Igarashi 《Applied microbiology and biotechnology》2010,87(4):1579-1586
We have reported for the first time that agricultural and cellulosic waste, i.e., rice straw was directly applied to methanogenic
bioreactors containing carbon fiber textiles (CFT) as supporting material. Addition of CFT to the methanogenic bioreactors
enhanced the conversion of dichromate chemical oxygen demand of the substrate to methane (41%) to a greater extent than bioreactors
without CFT (9%). In addition, removal of rice straw as a suspended solid was increased from 31% (in bioreactors without CFT)
to 57% (in those with CFT). Methanogenic 16S rRNA gene analysis showed that the abundance of acetoclastic methanogen, genus
Methanosarcina, was about 11 times higher in bioreactors with CFT (suspended fraction plus retained fraction to CFT) than in bioreactors
without CFT (suspended fraction), resulting in lower concentration of acetate in bioreactors with CFT (0.4 mM) than in those
without CFT (29.7 mM). On the other hand, the abundance of hydrogenotrophic methanogen, genus Methanobacterium, in bioreactors with CFT was similar to those without CFT. Bacterial communities in bioreactors with CFT were different from
those in bioreactors without CFT. Our results indicated that specific microbial community and cooperative relationships between
microorganisms in reactors containing CFT facilitated efficient decomposition of rice straw and its conversion to methane. 相似文献
6.
Bernd H. G. W. van Houten Wim van Doesburg Henk Dijkman Cris Copini Hauke Smidt Alfons J. M. Stams 《Applied microbiology and biotechnology》2009,84(3):555-563
The performance of a full-scale (500 m3) sulfidogenic synthesis gas fed gas-lift reactor treating metal- and sulfate-rich wastewater was investigated over a period
of 128 weeks. After startup, the reactor had a high methanogenic activity of 46 Nm3·h−1. Lowering the carbon dioxide feed rate during the first 6 weeks gradually lowered the methane production rate. Between weeks
8 and 93, less than 1% of the hydrogen supplied was used for methanogenesis. Denaturing gradient gel electrophoresis analysis
of polymerase chain reaction-amplified 16S rRNA gene fragments showed that the archaeal community decreased in diversity but
did not disappear completely. After the carbon dioxide feed rate increased in week 88, the methane production rate also increased,
confirming that methane production was carbon dioxide limited. Even though lowering the carbon dioxide feed appeared to affect
part of the sulfate-reducing community, it did not prevent achieving the desired rates of sulfate reduction. The average sulfate
conversion rate was 181 kg∙h−1 for the first 92 weeks. After 92 weeks, the sulfate input rate was increased and from week 94 to 128, the average weekly
sulfate conversion rate was 295 kg·h−1 (SD ± 87). Even higher sulfate conversion rates of up to 400 kg·h−1 could be sustained for weeks 120–128. The long-term performance and stability together with the ability to control methanogenesis
demonstrates that synthesis gas fed reactor can be used successfully at full scale to treat metal and sulfate-rich wastewater. 相似文献
7.
Sasaki K Morita M Hirano S Ohmura N Igarashi Y 《Applied microbiology and biotechnology》2011,90(4):1555-1561
Ammonia accumulation is one of the main causes of the loss of methane production observed during fermentation. We investigated
the effect of addition of carbon fiber textiles (CFT) to thermophilic methanogenic bioreactors with respect to ammonia tolerance
during the process of degradation of artificial garbage slurry, by comparing the performance of the reactors containing CFT
with the performance of reactors without CFT. Under total ammonia-N concentrations of 3,000 mg L−1, the reactors containing CFT were found to mediate stable removal of organic compounds and methane production. Under these
conditions, high levels of methanogenic archaea were retained at the CFT, as determined by 16S rRNA gene analysis for methanogenic
archaea. In addition, Methanobacterium sp. was found to be dominant in the suspended fraction, and Methanosarcina sp. was dominant in the retained fraction of the reactors with CFT. However, the reactors without CFT had lower rates of
removal of organic compounds and production of methane under total ammonia-N concentrations of 1,500 mg L−1. Under this ammonia concentration, a significant accumulation of acetate was observed in the reactors without CFT (130.0 mM),
relative to the reactors with CFT (4.2 mM). Only Methanobacterium sp. was identified in the reactors without CFT. These results suggest that CFT enables stable proliferation of aceticlastic
methanogens by preventing ammonia inhibition. This improves the process of stable garbage degradation and production of methane
in thermophilic bioreactors that include high levels of ammonia. 相似文献
8.
A bioelectrochemical reactor containing carbon fiber textiles enables efficient methane fermentation from garbage slurry 总被引:1,自引:0,他引:1
Sasaki K Morita M Sasaki D Hirano S Matsumoto N Watanabe A Ohmura N Igarashi Y 《Bioresource technology》2011,102(13):6837-6842
A packed-bed system includes supporting materials to retain microorganisms and a bioelectrochemical system influences the microbial metabolism. In our study, carbon fiber textiles (CFT) as a supporting material was attached onto a carbon working electrode in a bioelectrochemical reactor (BER) that degrades garbage slurry to methane, in order to investigate the effect of combining electrochemical regulation and packing CFT. The potential on the working electrode in the BER containing CFT was set to −1.0 V or −0.8 V (vs. Ag/AgCl). BERs containing CFT exhibited higher methane production, elimination of dichromate chemical oxygen demand, and the ratio of methanogens in the suspended fraction than reactors containing CFT without electrochemical regulation at an organic loading rate (OLR) of 27.8 gCODcr/L/day. In addition, BERs containing CFT exhibited higher reactor performances than BERs without CFT at this OLR. Our results revealed that the new design that combined electrochemical regulation and packing CFT was effective. 相似文献
9.
In this study, two laboratory-scale anaerobic batch reactors started up with different inoculum sludges and fed with the same
synthetic wastewater were monitored in terms of performance and microbial community shift by denaturant gradient gel electrophoresis
fingerprinting and subsequent cloning, sequencing analysis in order to reveal importance of initial quality of inoculum sludge
for operation of anaerobic reactors. For this purpose, two different seed sludge were evaluated. In Reactor1 seeded with a
sludge having less diverse microbial community (19 operational taxonomic unit (OTU’s) for Bacterial and 8 OTU’s for Archaeal
community, respectively) and a methanogenic activity of 150 ml CH4 g TVS−1 day−1, a chemical oxygen demand (COD) removal efficiency of 78.8 ± 4.17% was obtained at a substrate to microorganism (S/X) ratio
of 0.38. On the other hand, Reactor2, seeded with a sludge having a much more diverse microbial community (24 OTU’s for Bacterial
and 9 OTU’s for Archaeal communities, respectively) and a methanogenic activity, 450 ml CH4 g TVS−1 day−1, operated in the same conditions showed a better start-up performance; a COD removal efficiency of over 98% at a S/X ratio
of 0.53. Sequence analysis of Seed2 revealed the presence of diverse fermentative and syntrophic bacteria, whereas excised
bands of Seed1 related to fermentative and sulfate/metal-reducing bacteria. This study revealed that a higher degree of bacterial
diversity, especially the presence of syntrophic bacteria besides the abundance of key species such as methanogenic Archaea
may play an important role in the performance of anaerobic reactors during the start-up period. 相似文献
10.
Lay CY Mykytczuk NC Niederberger TD Martineau C Greer CW Whyte LG 《Extremophiles : life under extreme conditions》2012,16(2):177-191
Lost Hammer (LH) spring is a unique hypersaline, subzero, perennial high Arctic spring arising through thick permafrost. In
the present study, the microbial and geochemical characteristics of the LH outflow channels, which remain unfrozen at ≥−18°C
and are more aerobic/less reducing than the spring source were examined and compared to the previously characterized spring
source environment. LH channel sediments contained greater microbial biomass (~100-fold) and greater microbial diversity reflected
by the 16S rRNA clone libraries. Phylotypes related to methanogenesis, methanotrophy, sulfur reduction and oxidation were
detected in the bacterial clone libraries while the archaeal community was dominated by phylotypes most closely related to
THE ammonia-oxidizing Thaumarchaeota. The cumulative percent recovery of 14C-acetate mineralization in channel sediment microcosms exceeded ~30% and ~10% at 5 and −5°C, respectively, but sharply decreased
at −10°C (≤1%). Most bacterial isolates (Marinobacter, Planococcus, and Nesterenkonia spp.) were psychrotrophic, halotolerant, and capable of growth at −5°C. Overall, the hypersaline, subzero LH spring channel
has higher microbial diversity and activity than the source, and supports a variety of niches reflecting the more dynamic
and heterogeneous channel environment. 相似文献
11.
In this study, sludge was taken from a municipal wastewater treatment plant that contained a nearly equal number of archaeal
amoA genes (5.70 × 106 ± 3.30 × 105 copies mg sludge−1) to bacterial amoA genes (8.60 × 106 ± 7.64 × 105 copies mg sludge−1) and enriched in three continuous-flow reactors receiving an inorganic medium containing different ammonium concentrations:
2, 10, and 30 mM NH4+–N (28, 140, and 420 mg N l−1). The abundance and communities of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in enriched nitrifying
activated sludge (NAS) were monitored at days 60 and 360 of the operation. Early on, between day 0 and day 60 of reactor operation,
comparative abundance of AOA amoA genes to AOB amoA genes varied among the reactors depending on the ammonium levels found in the reactors. As compared to the seed sludge, the
number of AOA amoA genes was unchanged in the reactor with lower ammonium level (0.06 ± 0.04 mgN l−1), while in the reactors with higher ammonium levels (0.51 ± 0.33 and 0.25 ± 0.10 mgN l−1), the numbers of AOA amoA genes were deteriorated. By day 360, AOA disappeared from the ammonia-oxidizing consortiums in all reactors. The majority
of the AOA sequences from all NASs at each sampling period fell into a single AOA cluster, however, suggesting that the ammonium
did not affect the AOA communities under this operational condition. This result is contradictory to the case of AOB, where
the communities varied significantly among the NASs. AOB with a high affinity for ammonia were present in the reactors with
lower ammonium levels, whereas AOB with a low affinity to ammonia existed in the reactors with higher ammonium levels. 相似文献
12.
Bioremediation is of great interest in the detoxification of soil contaminated with residues from explosives such as hexahydro-1,3,5-trinitro-1,3,5-triazine
(RDX). Although there are numerous forms of in situ and ex situ bioremediation, ruminants would provide the option of an in situ bioreactor that could be transported to the site of contamination.
Bovine rumen fluid has been previously shown to transform 2,4,6-trinitrotoluene (TNT), a similar compound, in 4 h. In this
study, RDX incubated in whole ovine rumen fluid was nearly eliminated within 4 h. Whole ovine rumen fluid was then inoculated
into five different types of media to select for archaeal and bacterial organisms capable of RDX biotransformation. Cultures
containing 30 μg mL−1 RDX were transferred each time the RDX concentration decreased to 5 μg mL−1 or less. Time point samples were analyzed for RDX biotransformation by HPLC. The two fastest transforming enrichments were
in methanogenic and low nitrogen basal media. After 21 days, DNA was extracted from all enrichments able to partially or completely
transform RDX in 7 days or less. To understand microbial diversity, 16S rRNA-gene-targeted denaturing gradient gel electrophoresis
(DGGE) fingerprinting was conducted. Cloning and sequencing of partial 16S rRNA fragments were performed on both low nitrogen
basal and methanogenic media enrichments. Phylogenetic analysis revealed similar homologies to eight different bacterial and
one archaeal genera classified under the phyla Firmicutes, Actinobacteria, and Euryarchaeota. After continuing enrichment
for RDX degraders for 1 year, two consortia remained: one that transformed RDX in 4 days and one which had slowed after 2 months
of transfers without RDX. DGGE comparison of the slower transforming consortium to the faster one showed identical banding
patterns except one band. Homology matches to clones from the two consortia identified the same uncultured Clostridia genus in both; Sporanaerobacter acetigenes was identified only in the consortia able to completely transform RDX. This is the first study to examine the rumen as a
potential bioremediation tool for soils contaminated with RDX, as well as to discover S. acetigenes in the rumen and its potential ability to metabolize this energetic compound. 相似文献
13.
Anaerobic co-digestion of dairy manure with mulched switchgrass for improvement of the methane yield
The owners of farm-scale anaerobic digesters are relying on off-farm wastes or energy crops as a co-digestion feedstock with
animal manure in order to increase their production of methane and thus revenues. Switchgrass represents an interesting feedstock
for Canadian digesters owners as it is a high-yielding low-maintenance perennial crop, well adapted to northern climate. Methane
potential assays in batch tests showed methane production of 19.4 ± 3.6, 28.3 ± 1.7, 37.3 ± 7.1 and 45.7 ± 0.8 L kg−1, for raw manure, blended manure, manure and mulched switchgrass, manure and pretreated switchgrass, respectively. Two 6-L
lab-scale anaerobic digesters were operated for 130 days in order to assess the benefit of co-digesting switchgrass with bovine
manure (digester #2), at a 20% wet mass fraction, compared with a manure-only operation (digester #1) The digesters were operated
at an hydraulic retention time of 37 ± 6 days and at loads of 2.4 ± 0.6 and 2.6 ± 0.6 kg total volatile solids (TVS) L−1 day−1 for digesters #1 (D1) and #2 (D2), respectively. The TVS degradation reached 25 and 39%, which resulted in a methane production
of 1.18 ± 0.18 and 2.19 ± 0.31 L day−1 for D1 and D2, respectively. The addition of 20% on a wet mass ratio of switchgrass to a manure digester increased its methane
production by 86%. The co-digestion of switchgrass in a 500 m3 manure digester could yield up to 10.2 GJ day−1 of purified methane or 1.1 MWh day−1 of electricity. 相似文献
14.
15.
Fatma Abouelenien Yoshiaki Kitamura Naomichi Nishio Yutaka Nakashimada 《Applied microbiology and biotechnology》2009,82(4):757-764
The effect of temperature on production of ammonia during dry anaerobic fermentation of chicken manure (CM), inoculated with
thermophilic methanogenic sludge, was investigated in a batch condition for 8 days. Incubation temperature did not have a
significant effect on the production of ammonia. Almost complete inhibition of production of methane occurred at 55 and 65°C
while quite low yields of 8.45 and 6.34 ml g−1 VS (volatile solids) were observed at 35 and 45°C due to a higher accumulation of ammonia. In order to improve the production
of methane during dry anaerobic digestion of CM, stripping of ammonia was performed firstly on the CM previously fermented
at 65°C for 8 days: the stripping for 1 day at 85°C and pH 10 removed 85.5% of ammonia. The first-batch fermentation of methane
for 75 days was conducted next, using the ammonia-stripped CM inoculated with methanogenic sludge at different ratios, (CM:
thermophilic sludge) of 1:2, 1:1, and 2:1 on volume per volume basis at both 35 and 55°C. Production of methane improved and
was higher than that of the control (without stripping of ammonia) but the yield of 20.4 ml g−1 VS was still low, so second stripping of ammonia was conducted, which resulted in 74.7% removal of ammonia. A great improvement
in the production of methane of 103.5 ml g−1 VS was achieved during the second batch for 55 days. 相似文献
16.
Performance of a pilot-scale continuous flow microbial electrolysis cell fed winery wastewater 总被引:1,自引:0,他引:1
Cusick RD Bryan B Parker DS Merrill MD Mehanna M Kiely PD Liu G Logan BE 《Applied microbiology and biotechnology》2011,89(6):2053-2063
A pilot-scale (1,000 L) continuous flow microbial electrolysis cell was constructed and tested for current generation and
COD removal with winery wastewater. The reactor contained 144 electrode pairs in 24 modules. Enrichment of an exoelectrogenic
biofilm required ~60 days, which is longer than typically needed for laboratory reactors. Current generation was enhanced
by ensuring adequate organic volatile fatty acid content (VFA/SCOD ≥ 0.5) and by raising the wastewater temperature (31 ± 1°C).
Once enriched, SCOD removal (62 ± 20%) was consistent at a hydraulic retention time of 1 day (applied voltage of 0.9 V). Current
generation reached a maximum of 7.4 A/m3 by the planned end of the test (after 100 days). Gas production reached a maximum of 0.19 ± 0.04 L/L/day, although most of
the product gas was converted to methane (86 ± 6%). In order to increase hydrogen recovery in future tests, better methods
will be needed to isolate hydrogen gas produced at the cathode. These results show that inoculation and enrichment procedures
are critical to the initial success of larger-scale systems. Acetate amendments, warmer temperatures, and pH control during
startup were found to be critical for proper enrichment of exoelectrogenic biofilms and improved reactor performance. 相似文献
17.
Microbial and decomposition efficiencies of monoculture and polyculture vermireactors,based on epigeic and anecic earthworms 总被引:2,自引:0,他引:2
Surindra Suthar 《World journal of microbiology & biotechnology》2008,24(8):1471-1479
Efforts have been made to evaluate the microbial and decomposition efficiency of three different vermireactors: (i) polyculture
(introducing equal numbers of anecic and epigeic earthworms), (ii) monoculture (anecic) and (iii) monoculture (epigeic), designed
by using earthworms of two different ecological categories i.e. anecic (Lampito mauritii Kinberg) and epigeic (Eisenia fetida (Savigny)). The microbial load of vermireactors was measured through substrate-induced respiration rate (SIR), microbial
biomass N content and rate of dehydrogenase activity, while mineralization rate was evaluated measuring some chemical parameters
of the substrate. Earthworms caused a decrease (as compared to initial value) in pH (41.9–80.7%), organic C (10.3–14.2%) and
C:N ratio (41.9–80.7%) and an increase in total N (29.1–58.8%), NH4-N (876.1–1485.7%), NO3-N (29081.8–56792.6%), available P (16–19.4%) and exchangeable K (9.8–13.5%) contents of the substrate. The mineralization
efficiency of the reactors was in the order: polyculture (epigeic + anecic) > monoculture (anecic) > monoculture (epigeic).
The polyculture reactor showed the maximum rate of SIR (2.91 ± 0.2 mg CO2 g−1 substrate), microbial biomass N (3108.1 ± 289.2 mg N g−1 substrate), and dehydrogenase activity (2453.3 ± 379.8 μg g−1 substrate 24 h), while in the monoculture (epigeic) the lowest values of the same parameters were observed. It is concluded
that the observed differences among reactors were due to different feeding behaviour and niche structures of epigeic and anecic
earthworms. Data suggests that burrowing earthworms in waste-decomposing-system not only enhance the microbial efficiencies,
but at the same time also accelerate the organic matter mineralization in a vermireactor. However, most of the previous studies
were based on monoculture reactors (using epigeic earthworms) which have been recommended for waste decomposition operations,
but this study revealed that polyculture vermicomposting (adding of burrowing worms with epigeic earthworms in vermicomposting
system) might be beneficial for rapid decomposition of organic wastes. 相似文献
18.
Microbial communities inhabiting highly permeable sediments of Checker Reef in Kaneohe Bay, Hawaii, were characterized in
relation to porewater geochemistry (O2, NO3
−, NO2
−, NH4
+, phosphate). The physiologically active part of the population, assessed by sequencing cDNA libraries of 16S rRNA amplicons,
was very diverse, with an estimated ribotype richness ≥1,380 in anoxic sediment. Quantitative analysis of community structure
by rRNA-targeted fluorescence in situ hybridization (FISH) indicated that the archaeal population (9–18%) was dominated by
marine Crenarchaeota (5–9%). Planctomycetales were the most abundant group in the oxic and interfacial habitat (17–19%) but
were a minority (<5%) in anoxic reef sediment, where γ-Proteobacteria were numerically dominant (18%). Another 9–14% of the
microbial benthos belonged to β-Proteobacteria, predominantly within the order Nitrosomonadales, many cultured representatives
of which are NH4
+ oxidizers. The results of this study contribute to the phylogenetic characterization of benthic microbial communities that
are important in organic matter degradation and nutrient recycling in coral reef ecosystems. 相似文献
19.
In situ enrichment experiments were carried out in the Arctic deep sea (Fram Strait region) to observe the response of benthic
microbial communities to chitin supply. Chambers of a benthic lander were filled in July 2004 with deep-sea sediments enriched
with 1.3–7.0 g m−2 of chitin and the effects of chitin enrichment were assessed on the microbial hydrolytic activity potential, cell number
and community structure after periods of 1 week and 1 year of in situ deployment. The input of chitin had no effect on microbial
abundance and chitobiase activity after 7 days of incubation, whereas community structure in enriched sediments, determined
by terminal restriction fragment length polymorphism analysis of 16S rRNA genes, was different from the controls. After 1 year,
microbial numbers and activity significantly increased in sediments enriched with high chitin concentrations and bacterial
community structure was different from that of the other treatments. The present study suggests that microbial community structure
in Arctic deep-sea sediments can react quickly to sudden large chitin inputs into the sediments and that this appears to precondition
subsequent enhanced growth and enzymatic activity changes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
Microorganisms are known to play fundamental roles in the biogeochemical cycling of carbon in the coastal environments. To
get to know the composition and ecological roles of the archaeal communities within the sediments of the Pearl River Estuary,
Southern China, the diversity and vertical distribution of archaea in a sediment core was reported based on the 16S rRNA and
mcrA genes for the first time. Quantitative PCR analysis revealed that archaea were present at 106–107 16S rRNA gene copies/g (wet weight) in the sediment core, and the proportion of mcrA versus 16S rRNA gene copies varied from 11 to 45%. 16S rRNA gene libraries were constructed and analyzed for the top layer
(0–6 cm), middle layer (18–24 cm), sulfate-methane transition zone (SMTZ, 32–42 cm), and bottom layer (44–50 cm) sediments.
The results indicated that Miscellaneous Crenarchaeotal Group (MCG) was the main component in the sediments. The MCG archaea
could be further divided into six subgroups: MCG-A, B, C, D, E, and F. On the other hand, mcrA sequences from methanogens related to the order Methanomicrobiales and ANME-2 methanotrophs were detected in all sediment layers. Taken together, our data revealed a largely unknown archaeal
community in which MCG dominated within the Pearl River estuarine sediments, while methanogens and methane-oxidizing archaea
putatively involving in methane metabolism, were also found in the community. This is the first important step towards elucidating
the biogeochemical roles of these archaea in the Pearl River Estuary. 相似文献