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1
Li, Junwei, Suwen Chen, Peng Wu, Changbo Zhu, Ruiping Hu, Ting Li et Yongjian Guo. « Insights into the Relationship between Intestinal Microbiota of the Aquaculture Worm Sipunculus nudus and Surrounding Sediments ». Fishes 8, no 1 (3 janvier 2023) : 32. http://dx.doi.org/10.3390/fishes8010032.
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Sipunculus nudus is an important intertidal aquaculture species that can ingest organic matter from the surface sediment and shows a high transportation capacity in sediment. However, little is known about the influence of intertidal aquaculture species on the sediment microbial community and the exchange of microbiota between the intestine and the surrounding sediment. In this study, the microbial communities in the intestine of S. nudus and three kinds of surrounding sediments were analyzed using high-throughput sequencing of the 16S rRNA gene amplicon, and the relationships between different communities were examined. Principal coordinate analysis and ANOSIM/Adonis analysis showed that the microbial communities of worm intestine samples were significantly different from those of surrounding sediments (p < 0.05). Meanwhile, compared with the sediment samples, the microbial α-diversity was significantly lower in the intestinal samples. Although the relative abundances of Proteobacteria and Cyanobacteria were high in all samples, three phyla (Bacteroidetes, Gemmatimonadetes, and Latescibacteria) showed a great difference between the four groups, as the abundances of the three phyla were significantly lower in the intestinal samples. Moreover, several microbial interactions were found between the worm intestine and surrounding sediments. BugBase functional prediction analysis indicated that the oxygen status of the sediment and the intestine was changed by bioturbation by the worm. Therefore, the microenvironment and microbial community in sediment were affected by the activity of S. nudus in the intertidal aquaculture zone.
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Oest, Adam, Ali Alsaffar, Mitchell Fenner, Dominic Azzopardi et Sonia M. Tiquia-Arashiro. « Patterns of Change in Metabolic Capabilities of Sediment Microbial Communities in River and Lake Ecosystems ». International Journal of Microbiology 2018 (27 mai 2018) : 1–15. http://dx.doi.org/10.1155/2018/6234931.
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Information on the biodegradation potential of lake and river microbial communities is essential for watershed management. The water draining into the lake ecosystems often carries a significant amount of suspended sediments, which are transported by rivers and streams from the local drainage basin. The organic carbon processing in the sediments is executed by heterotrophic microbial communities, whose activities may vary spatially and temporally. Thus, to capture and apprehend some of these variabilities in the sediments, we sampled six sites: three from the Saint Clair River (SC1, SC2, and SC3) and three from Lake Saint Clair in the spring, summer, fall, and winter of 2016. Here, we investigated the shifts in metabolic profiles of sediment microbial communities, along Saint Clair River and Lake Saint Clair using Biolog EcoPlates, which test for the oxidation of 31 carbon sources. The number of utilized substrates was generally higher in the river sediments (upstream) than in the lake sediments (downstream), suggesting a shift in metabolic activities among microbial assemblages. Seasonal and site-specific differences were also found in the numbers of utilized substrates, which were similar in the summer and fall, and spring and winter. The sediment microbial communities in the summer and fall showed more versatile substrate utilization patterns than spring and winter communities. The functional fingerprint analyses clearly distinguish the sediment microbial communities from the lake sites (downstream more polluted sites), which showed a potential capacity to use more complex carbon substrates such as polymers. This study establishes a close linkage between physical and chemical properties (temperature and organic matter content) of lake and river sediments and associated microbial functional activities.
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Rutere, Cyrus, Kirsten Knoop, Malte Posselt, Adrian Ho et Marcus A. Horn. « Ibuprofen Degradation and Associated Bacterial Communities in Hyporheic Zone Sediments ». Microorganisms 8, no 8 (16 août 2020) : 1245. http://dx.doi.org/10.3390/microorganisms8081245.
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Ibuprofen, a non-steroidal anti-inflammatory pain reliever, is among pharmaceutical residues of environmental concern ubiquitously detected in wastewater effluents and receiving rivers. Thus, ibuprofen removal potentials and associated bacteria in the hyporheic zone sediments of an impacted river were investigated. Microbially mediated ibuprofen degradation was determined in oxic sediment microcosms amended with ibuprofen (5, 40, 200, and 400 µM), or ibuprofen and acetate, relative to an un-amended control. Ibuprofen was removed by the original sediment microbial community as well as in ibuprofen-enrichments obtained by re-feeding of ibuprofen. Here, 1-, 2-, 3-hydroxy- and carboxy-ibuprofen were the primary transformation products. Quantitative real-time PCR analysis revealed a significantly higher 16S rRNA abundance in ibuprofen-amended relative to un-amended incubations. Time-resolved microbial community dynamics evaluated by 16S rRNA gene and 16S rRNA analyses revealed many new ibuprofen responsive taxa of the Acidobacteria, Actinobacteria, Bacteroidetes, Gemmatimonadetes, Latescibacteria, and Proteobacteria. Two ibuprofen-degrading strains belonging to the genera Novosphingobium and Pseudomonas were isolated from the ibuprofen-enriched sediments, consuming 400 and 300 µM ibuprofen within three and eight days, respectively. The collective results indicated that the hyporheic zone sediments sustain an efficient biotic (micro-)pollutant degradation potential, and hitherto unknown microbial diversity associated with such (micro)pollutant removal.
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Wang, Yu, Hua-Fang Sheng, Yan He, Jin-Ya Wu, Yun-Xia Jiang, Nora Fung-Yee Tam et Hong-Wei Zhou. « Comparison of the Levels of Bacterial Diversity in Freshwater, Intertidal Wetland, and Marine Sediments by Using Millions of Illumina Tags ». Applied and Environmental Microbiology 78, no 23 (21 septembre 2012) : 8264–71. http://dx.doi.org/10.1128/aem.01821-12.
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ABSTRACTSediment, a special realm in aquatic environments, has high microbial diversity. While there are numerous reports about the microbial community in marine sediment, freshwater and intertidal sediment communities have been overlooked. The present study determined millions of Illumina reads for a comparison of bacterial communities in freshwater, intertidal wetland, and marine sediments along Pearl River, China, using a technically consistent approach. Our results show that both taxon richness and evenness were the highest in freshwater sediment, medium in intertidal sediment, and lowest in marine sediment. The high number of sequences allowed the determination of a wide variety of bacterial lineages in all sediments for reliable statistical analyses. Principal component analysis showed that the three types of communities could be well separated from phylum to operational taxonomy unit (OTU) levels, and the OTUs from abundant to rare showed satisfactory resolutions. Statistical analysis (LEfSe) demonstrated that the freshwater sediment was enriched withAcidobacteria,Nitrospira,Verrucomicrobia,Alphaproteobacteria, andBetaproteobacteria. The intertidal sediment had a unique community with diverse primary producers (such asChloroflexi,Bacillariophyta,Gammaproteobacteria, andEpsilonproteobacteria) as well as saprophytic microbes (such asActinomycetales,Bacteroidetes, andFirmicutes). The marine sediment had a higher abundance ofGammaproteobacteriaandDeltaproteobacteria, which were mainly involved in sulfate reduction in anaerobic conditions. These results are helpful for a systematic understanding of bacterial communities in natural sediment environments.
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Wu, Miao, Ming Zhang, Wei Ding, Lin Lan, Zhilin Liu, Lingzhan Miao et Jun Hou. « Microbial Carbon Metabolic Functions in Sediments Influenced by Resuspension Event ». Water 13, no 1 (23 décembre 2020) : 7. http://dx.doi.org/10.3390/w13010007.
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Microorganisms in sediments are an important part of the aquatic ecosystem, and their functional activities are sensitive to external environmental pressure. Shallow lakes are characterized by frequent sediment resuspension events, leading to large amounts of nutrients being released. However, information about the potential impacts of sediment resuspension events on the functional activities of microbial communities is limited. In this study, the responses of microbial carbon metabolism in sediments under different wind–wave disturbance were analyzed by BIOLOG ECO microplates. The results showed that under four disturbance conditions (wind speeds of 0, 1.60, 3.62, and 14.10 m/s), the total carbon metabolism function of the sediment microbial community (represented as average well-color development, AWCD) remained unchanged (p > 0.05), and the final total AWCD value stabilized at about 1.70. However, compared with the control group, some specific carbon sources (e.g., amines and carboxylic acids) showed significant changes (p < 0.05). We found that short-term (8 h) resuspension events did not affect the total carbon metabolism of sediment microbial communities, while it affected the microbial utilization ability of some specific types of carbon sources. For example, we found that the microbial utilization capacity of polymers in the 14.10 m/s group was the best. This study provides a new insight into the carbon cycle process of shallow lake sediments that resuspension events will affect the carbon cycle process of sediments.
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Kuo, Jimmy, Daniel Liu et Chorng-Horng Lin. « Functional Prediction of Microbial Communities in Sediment Microbial Fuel Cells ». Bioengineering 10, no 2 (3 février 2023) : 199. http://dx.doi.org/10.3390/bioengineering10020199.
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Sediment microbial fuel cells (MFCs) were developed in which the complex substrates present in the sediment could be oxidized by microbes for electron production. In this study, the functional prediction of microbial communities of anode-associated soils in sediment MFCs was investigated based on 16S rRNA genes. Four computational approaches, including BugBase, Functional Annotation of Prokaryotic Taxa (FAPROTAX), the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2), and Tax4Fun2, were applied. A total of 67, 9, 37, and 38 functional features were statistically significant. Among these functional groups, the function related to the generation of precursor metabolites and energy was the only one included in all four computational methods, and the sum total of the proportion was 93.54%. The metabolism of cofactor, carrier, and vitamin biosynthesis was included in the three methods, and the sum total of the proportion was 29.94%. The results suggested that the microbial communities usually contribute to energy metabolism, or the metabolism of cofactor, carrier, and vitamin biosynthesis might reveal the functional status in the anode of sediment MFCs.
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Laverock, Bonnie, Jack A. Gilbert, Karen Tait, A. Mark Osborn et Steve Widdicombe. « Bioturbation : impact on the marine nitrogen cycle ». Biochemical Society Transactions 39, no 1 (19 janvier 2011) : 315–20. http://dx.doi.org/10.1042/bst0390315.
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Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significantly affect these microbial processes by altering the physicochemical properties of the sediment. For example, the building and irrigation of burrows by bioturbators introduces fresh oxygenated water into deeper sediment layers and allows the exchange of solutes between the sediment and water column. Burrows can effectively extend the oxic/anoxic interface into deeper sediment layers, thus providing a unique environment for nitrogen-cycling microbial communities. Recent studies have shown that the abundance and diversity of micro-organisms can be far greater in burrow wall sediment than in the surrounding surface or subsurface sediment; meanwhile, bioturbated sediment supports higher rates of coupled nitrification–denitrification reactions and increased fluxes of ammonium to the water column. In the present paper we discuss the potential for bioturbation to significantly affect marine nitrogen cycling, as well as the molecular techniques used to study microbial nitrogen cycling communities and directions for future study.
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Hölker, Franz, Christian Wurzbacher, Carsten Weißenborn, Michael T. Monaghan, Stephanie I. J. Holzhauer et Katrin Premke. « Microbial diversity and community respiration in freshwater sediments influenced by artificial light at night ». Philosophical Transactions of the Royal Society B : Biological Sciences 370, no 1667 (5 mai 2015) : 20140130. http://dx.doi.org/10.1098/rstb.2014.0130.
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An increasing proportion of the Earth's surface is illuminated at night. In aquatic ecosystems, artificial light at night (ALAN) may influence microbial communities living in the sediments. These communities are highly diverse and play an important role in the global carbon cycle. We combined field and laboratory experiments using sediments from an agricultural drainage system to examine how ALAN affects communities and alters carbon mineralization. Two identical light infrastructures were installed parallel to a drainage ditch before the start of the experiment. DNA metabarcoding indicated that both sediment communities were similar. After one was lit for five months (July–December 2012) we observed an increase in photoautotroph abundance (diatoms, Cyanobacteria ) in ALAN-exposed sediments. In laboratory incubations mimicking summer and winter (six weeks each), communities in sediments that were exposed to ALAN for 1 year (July 2012–June 2013) showed less overall seasonal change compared with ALAN-naive sediments. Nocturnal community respiration was reduced in ALAN-exposed sediments. In long-term exposed summer-sediments, we observed a shift from negative to positive net ecosystem production. Our results indicate ALAN may alter sediment microbial communities over time, with implications for ecosystem-level functions. It may thus have the potential to transform inland waters to nocturnal carbon sinks.
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Marfil-Santana, Miguel David, Anahí Martínez-Cárdenas, Analuisa Ruíz-Hernández, Mario Vidal-Torres, Norma Angélica Márquez-Velázquez, Mario Figueroa et Alejandra Prieto-Davó. « A Meta-Omics Analysis Unveils the Shift in Microbial Community Structures and Metabolomics Profiles in Mangrove Sediments Treated with a Selective Actinobacterial Isolation Procedure ». Molecules 26, no 23 (2 décembre 2021) : 7332. http://dx.doi.org/10.3390/molecules26237332.
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Mangrove sediment ecosystems in the coastal areas of the Yucatan peninsula are unique environments, influenced by their karstic origin and connection with the world’s largest underground river. The microbial communities residing in these sediments are influenced by the presence of mangrove roots and the trading chemistry for communication between sediment bacteria and plant roots can be targeted for secondary metabolite research. To explore the secondary metabolite production potential of microbial community members in mangrove sediments at the “El Palmar” natural reserve in Sisal, Yucatan, a combined meta-omics approach was applied. The effects of a cultivation medium reported to select for actinomycetes within mangrove sediments’ microbial communities was also analyzed. The metabolome of the microbial communities was analyzed by high-resolution liquid chromatography-tandem mass spectrometry, and molecular networking analysis was used to investigate if known natural products and their variants were present. Metagenomic results suggest that the sediments from “El Palmar” harbor a stable bacterial community independently of their distance from mangrove tree roots. An unexpected decrease in the observed abundance of actinomycetes present in the communities occurred when an antibiotic-amended medium considered to be actinomycete-selective was applied for a 30-day period. However, the use of this antibiotic-amended medium also enhanced production of secondary metabolites within the microbial community present relative to the water control, suggesting the treatment selected for antibiotic-resistant bacteria capable of producing a higher number of secondary metabolites. Secondary metabolite mining of “El Palmar” microbial community metagenomes identified polyketide synthase and non-ribosomal peptide synthetases’ biosynthetic genes in all analyzed metagenomes. The presence of these genes correlated with the annotation of several secondary metabolites from the Global Natural Product Social Molecular Networking database. These results highlight the biotechnological potential of the microbial communities from “El Palmar”, and show the impact selective media had on the composition of communities of actinobacteria.
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Tufail, Azra. « Microbial communities colonising nutrient-enriched marine sediment ». Hydrobiologia 148, no 3 (mai 1987) : 245–55. http://dx.doi.org/10.1007/bf00017527.
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Yang, Yuyin, Ningning Li, Wei Wang, Bingxin Li, Shuguang Xie et Yong Liu. « Vertical profiles of sediment methanogenic potential and communities in two plateau freshwater lakes ». Biogeosciences 14, no 2 (24 janvier 2017) : 341–51. http://dx.doi.org/10.5194/bg-14-341-2017.
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Abstract. Microbial methanogenesis in sediment plays a crucial role in CH4 emission from freshwater lake ecosystems. However, knowledge of the layer-depth-related changes of methanogen community structure and activities in freshwater lake sediment is still limited. The present study was conducted to characterize the methanogenesis potential in different sediment-layer depths and the vertical distribution of microbial communities in two freshwater lakes of different trophic status on the Yunnan Plateau (China). Incubation experiments and inhibitor studies were carried out to determine the methanogenesis potential and pathways. 16S rRNA and mcrA genes were used to investigate the abundance and structure of methanogen and archaeal communities, respectively. Hydrogenotrophic methanogenesis was mainly responsible for methane production in sediments of both freshwater lakes. The layer-depth-related changes of methanogenesis potential and the abundance and community structure of methanogens were observed in both Dianchi Lake and Erhai Lake. Archaeal 16S rRNA and mcrA genes displayed a similar abundance change pattern in both lakes, and the relative abundance of methanogens decreased with increasing sediment-layer depth. Archaeal communities differed considerably in Dianchi Lake and Erhai Lake, but methanogen communities showed a slight difference between these two lakes. However, methanogen communities illustrated a remarkable layer-depth-related change. Order Methanomicrobiales was the dominant methanogen group in all sediments, while Methanobacteriales showed a high proportion only in upper layer sediments. The trophic status of the lake might have a notable influence on the depth-related change pattern of methanogenesis activity, while the methanogen community structure was mainly influenced by sediment depth.
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Elmer, Wade H., Peter Thiel et Blaire Steven. « Response of Sediment Bacterial Communities to Sudden Vegetation Dieback in a Coastal Wetland ». Phytobiomes Journal 1, no 1 (janvier 2017) : 5–13. http://dx.doi.org/10.1094/pbiomes-09-16-0006-r.
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There is an increasing recognition of the role coastal vegetated ecosystems play in atmospheric carbon sequestration. However, the development of sudden vegetation dieback (SVD), a phenomenon that causes the rapid death of Spartina alterniflora, followed by no or slow recovery, has affected large-scale alterations in Atlantic coastal systems. This study reports the effects of the development of SVD on the sediment microbial communities. In 1999, Hammonasset Beach State Park in Connecticut experienced the initial appearance of SVD. After more than a decade, the plants have not recovered. Yet, sediment chemistry was similar between vegetated and SVD affected sites, with the exception of water loading, which was significantly higher in the SVD affected sites. Soil CO2 flux, a proxy for soil respiration, was reduced by 64% in SVD sites compared with sites that remained vegetated. This suggests that SVD has affected large changes in carbon cycling in the wetland sediments. The microbial communities between vegetated and SVD sites were significantly different, as assessed by 16S rRNA gene sequencing. The vegetated sediments harbored significantly higher populations of Bacteroidetes-related bacteria, whereas the SVD affected sediments contained a significantly enriched relative abundance of sulfate-reducing bacteria, predominantly within the genus Desulfobulbus. Thus, the development of SVD appears to favor anaerobic metabolic pathways at the expense of saprophytes. Greenhouse experiments testing if the alterations in the sediment microbial communities were associated with differences in S. alterniflora germination or growth were also pursued. Although small differences in growth and disease ratings were noted between seedling and transplants grown in soil mix (control), autoclaved SVD sediments, or non-autoclaved (natural) SVD sediments, mortality was not significantly different, indicating that the alterations in the sediment communities are not likely responsible for SVD, or a primary cause for the failure of S. alterniflora to recolonize the SVD sites.
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Wyness, Adam J., Irene Fortune, Andrew J. Blight, Patricia Browne, Morgan Hartley, Matthew Holden et David M. Paterson. « Ecosystem engineers drive differing microbial community composition in intertidal estuarine sediments ». PLOS ONE 16, no 2 (19 février 2021) : e0240952. http://dx.doi.org/10.1371/journal.pone.0240952.
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Intertidal systems are complex and dynamic environments with many interacting factors influencing biochemical characteristics and microbial communities. One key factor are the actions of resident fauna, many of which are regarded as ecosystem engineers because of their bioturbation, bioirrigation and sediment stabilising activities. The purpose of this investigation was to elucidate the evolutionary implications of the ecosystem engineering process by identifying, if any, aspects that act as selection pressures upon microbial communities. A mesocosm study was performed using the well characterised intertidal ecosystem engineers Corophium volutator, Hediste diversicolor, and microphytobenthos, in addition to manual turbation of sediments to compare effects of bioturbation, bioirrigation and stabilisation. A range of sediment functions and biogeochemical gradients were measured in conjunction with 16S rRNA sequencing and diatom taxonomy, with downstream bacterial metagenome function prediction, to identify selection pressures that incited change to microbial community composition and function. Bacterial communities were predominantly Proteobacteria, with the relative abundance of Bacteroidetes, Alphaproteobacteria and Verrucomicrobia being partially displaced by Deltaproteobacteria, Acidobacteria and Chloroflexi as dissolved oxygen concentration and redox potential decreased. Bacterial community composition was driven strongly by biogeochemistry; surface communities were affected by a combination of sediment functions and overlying water turbidity, and subsurface communities by biogeochemical gradients driven by sediment reworking. Diatom communities were dominated by Nitzschia laevis and Achnanthes sp., and assemblage composition was influenced by overlying water turbidity (manual or biogenic) rather than direct infaunal influences such as grazing.
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Boulding, A. N., G. N. Rees, D. S. Baldwin, P. J. Suter et G. O. Watson. « Changes in sediment microbial community structure within a large water-storage reservoir during an extreme drawdown event ». Marine and Freshwater Research 59, no 10 (2008) : 890. http://dx.doi.org/10.1071/mf07232.
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Although drought and drying of waters occur globally, the effect of drying on sediment microbial communities underpinning aquatic biogeochemical processes is poorly understood. We used the molecular method of terminal-restriction fragment length polymorphism (T-RFLP) to assess changes in the microbial community structure of sediments undergoing different levels of inundation and drying within a reservoir during drawdown in a drought. Sediments with three hydrological conditions were investigated: dry sediments (no overlying water), littoral sediments (covered with 1–2 mm water) and inundated sediments (covered with >1 m water). Sampling was done in winter 2006 (August) and summer 2007 (January) in Lake Hume, Australia. The microbial communities differed significantly between the different levels of inundation at each sampling time. Community structure also changed significantly within each site between winter 2006 and summer 2007, possibly influenced by the change of season or protracted drying. Sites that were ‘littoral’ in winter 2006 became ‘dry’ in summer 2007, and became more similar to communities that were ‘dry’ at both sampling times. This suggested that the hydrological history of specific sites did not heavily influence the response of microbial communities to severe drying, and all communities undergoing ‘dry’ conditions within the summer 2007 sampling responded similarly.
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Weisbrod, Barbara, Susanna A. Wood, Konstanze Steiner, Ruby Whyte-Wilding, Jonathan Puddick, Olivier Laroche et Daniel R. Dietrich. « Is a Central Sediment Sample Sufficient ? Exploring Spatial and Temporal Microbial Diversity in a Small Lake ». Toxins 12, no 9 (9 septembre 2020) : 580. http://dx.doi.org/10.3390/toxins12090580.
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(1) Background: Paleolimnological studies use sediment cores to explore long-term changes in lake ecology, including occurrences of harmful cyanobacterial blooms. Most studies are based on single cores, assuming this is representative of the whole lake, but data on small-scale spatial variability of microbial communities in lake sediment are scarce. (2) Methods: Surface sediments (top 0.5 cm) from 12 sites (n = 36) and two sediment cores were collected in Lake Rotorua (New Zealand). Bacterial community (16S rRNA metabarcoding), Microcystis specific 16S rRNA, microcystin synthetase gene E (mcyE) and microcystins (MCs) were assessed. Radionuclide measurements (210Pb, 137Cs) were used to date sediments. (3) Results: Bacterial community, based on relative abundances, differed significantly between surface sediment sites (p < 0.001) but the majority of bacterial amplicon sequence variants (88.8%) were shared. Despite intense MC producing Microcystis blooms in the past, no Microcystis specific 16S rRNA, mcyE and MCs were found in surface sediments but occurred deeper in sediment cores (approximately 1950′s). 210Pb measurements showed a disturbed profile, similar to patterns previously observed, as a result of earthquakes. (4) Conclusions: A single sediment core can capture dominant microbial communities. Toxin producing Microcystis blooms are a recent phenomenon in Lake Rotorua. We posit that the absence of Microcystis from the surface sediments is a consequence of the Kaikoura earthquake two years prior to our sampling.
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Ramírez, Gustavo A., Paraskevi Mara, Taylor Sehein, Gunter Wegener, Christopher R. Chambers, Samantha B. Joye, Richard N. Peterson et al. « Environmental factors shaping bacterial, archaeal and fungal community structure in hydrothermal sediments of Guaymas Basin, Gulf of California ». PLOS ONE 16, no 9 (8 septembre 2021) : e0256321. http://dx.doi.org/10.1371/journal.pone.0256321.
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The flanking regions of Guaymas Basin, a young marginal rift basin located in the Gulf of California, are covered with thick sediment layers that are hydrothermally altered due to magmatic intrusions. To explore environmental controls on microbial community structure in this complex environment, we analyzed site- and depth-related patterns of microbial community composition (bacteria, archaea, and fungi) in hydrothermally influenced sediments with different thermal conditions, geochemical regimes, and extent of microbial mats. We compared communities in hot hydrothermal sediments (75-100°C at ~40 cm depth) covered by orange-pigmented Beggiatoaceae mats in the Cathedral Hill area, temperate sediments (25-30°C at ~40 cm depth) covered by yellow sulfur precipitates and filamentous sulfur oxidizers at the Aceto Balsamico location, hot sediments (>115°C at ~40 cm depth) with orange-pigmented mats surrounded by yellow and white mats at the Marker 14 location, and background, non-hydrothermal sediments (3.8°C at ~45 cm depth) overlain with ambient seawater. Whereas bacterial and archaeal communities are clearly structured by site-specific in-situ thermal gradients and geochemical conditions, fungal communities are generally structured by sediment depth. Unexpectedly, chytrid sequence biosignatures are ubiquitous in surficial sediments whereas deeper sediments contain diverse yeasts and filamentous fungi. In correlation analyses across different sites and sediment depths, fungal phylotypes correlate to each other to a much greater degree than Bacteria and Archaea do to each other or to fungi, further substantiating that site-specific in-situ thermal gradients and geochemical conditions that control bacteria and archaea do not extend to fungi.
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Hoshino, Tatsuhiko, Hideyuki Doi, Go-Ichiro Uramoto, Lars Wörmer, Rishi R. Adhikari, Nan Xiao, Yuki Morono, Steven D’Hondt, Kai-Uwe Hinrichs et Fumio Inagaki. « Global diversity of microbial communities in marine sediment ». Proceedings of the National Academy of Sciences 117, no 44 (19 octobre 2020) : 27587–97. http://dx.doi.org/10.1073/pnas.1919139117.
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Microbial life in marine sediment contributes substantially to global biomass and is a crucial component of the Earth system. Subseafloor sediment includes both aerobic and anaerobic microbial ecosystems, which persist on very low fluxes of bioavailable energy over geologic time. However, the taxonomic diversity of the marine sedimentary microbial biome and the spatial distribution of that diversity have been poorly constrained on a global scale. We investigated 299 globally distributed sediment core samples from 40 different sites at depths of 0.1 to 678 m below the seafloor. We obtained ∼47 million 16S ribosomal RNA (rRNA) gene sequences using consistent clean subsampling and experimental procedures, which enabled accurate and unbiased comparison of all samples. Statistical analysis reveals significant correlations between taxonomic composition, sedimentary organic carbon concentration, and presence or absence of dissolved oxygen. Extrapolation with two fitted species–area relationship models indicates taxonomic richness in marine sediment to be 7.85 × 103to 6.10 × 105and 3.28 × 104to 2.46 × 106amplicon sequence variants for Archaea and Bacteria, respectively. This richness is comparable to the richness in topsoil and the richness in seawater, indicating that Bacteria are more diverse than Archaea in Earth’s global biosphere.
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Fiskal, Annika, Aixala Gaillard, Sebastien Giroud, Dejan Malcic, Prachi Joshi, Michael Sander, Carsten J. Schubert et Mark Alexander Lever. « Effects of Macrofaunal Recolonization on Biogeochemical Processes and Microbiota—A Mesocosm Study ». Water 13, no 11 (6 juin 2021) : 1599. http://dx.doi.org/10.3390/w13111599.
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Macroinvertebrates are widespread in lake sediments and alter sedimentary properties through their activity (bioturbation). Understanding the interactions between bioturbation and sediment properties is important given that lakes are important sinks and sources of carbon and nutrients. We studied the biogeochemical impact of macrofauna on surface sediments in 3-month-long mesocosm experiments conducted using sediment cores from a hypoxic, macrofauna-free lake basin. Experimental units consisted of hypoxic controls, oxic treatments, and oxic treatments that were experimentally colonized with chironomid larvae or tubificid worms. Overall, the presence of O2 in bottom water had the strongest geochemical effect and led to oxidation of sediments down to 2 cm depth. Relative to macrofauna-free oxic treatments, chironomid larvae increased sediment pore water concentrations of nitrate and sulfate and lowered porewater concentrations of reduced metals (Fe2+, Mn2+), presumably by burrow ventilation, whereas tubificid worms increased the redox potential, possibly through sediment reworking. Microbial communities were very similar across oxic treatments; however, the fractions of α-, β-, and γ-Proteobacteria and Sphingobacteriia increased, whereas those of Actinobacteria, Planctomycetes, and Omnitrophica decreased compared to hypoxic controls. Sediment microbial communities were, moreover, distinct from those of macrofaunal tubes or feces. We suggest that, under the conditions studied, bottom water oxygenation has a stronger biogeochemical impact on lacustrine surface sediments than macrofaunal bioturbation.
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Pop Ristova, P., F. Wenzhöfer, A. Ramette, M. Zabel, D. Fischer, S. Kasten et A. Boetius. « Bacterial diversity and biogeochemistry of different chemosynthetic habitats of the REGAB cold seep (West African margin, 3160 m water depth) ». Biogeosciences Discussions 9, no 7 (12 juillet 2012) : 8337–85. http://dx.doi.org/10.5194/bgd-9-8337-2012.
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Abstract. The giant pockmark REGAB (West African margin, 3160 m water depth) is an active methane-emitting cold seep ecosystem, where the energy derived from microbially mediated oxidation of methane supports high biomass and diversity of chemosynthetic communities. Bare sediments interspersed with heterogeneous chemosynthetic assemblages of mytilid mussels, vesicomyid clams and siboglinid tubeworms form a complex seep ecosystem. To better understand if benthic bacterial communities reflect the patchy distribution of chemosynthetic fauna, all major chemosynthetic habitats at REGAB were investigated using an interdisciplinary approach combining porewater geochemistry, in situ quantification of fluxes and consumption of methane, as well bacterial community fingerprinting. This study revealed that sediments populated by different fauna assemblages show distinct biogeochemical activities and are associated with distinct sediment bacterial communities. The methane consumption and methane effluxes ranged over one to two orders of magnitude across habitats, and reached highest values at the mussel habitat, which hosted a different bacterial community compared to the other habitats. Clam assemblages had a profound impact on the sediment geochemistry, but less so on the bacterial community structure. Moreover, all clam assemblages at REGAB were restricted to sediments characterized by complete methane consumption in the seafloor, and intermediate biogeochemical activity. Overall, variations in the sediment geochemistry were reflected in the distribution of both fauna and microbial communities; and were mostly determined by methane flux.
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Pop Ristova, P., F. Wenzhöfer, A. Ramette, M. Zabel, D. Fischer, S. Kasten et A. Boetius. « Bacterial diversity and biogeochemistry of different chemosynthetic habitats of the REGAB cold seep (West African margin, 3160 m water depth) ». Biogeosciences 9, no 12 (7 décembre 2012) : 5031–48. http://dx.doi.org/10.5194/bg-9-5031-2012.
Texte intégralRésumé :
Abstract. The giant pockmark REGAB (West African margin, 3160 m water depth) is an active methane-emitting cold seep ecosystem, where the energy derived from microbially mediated oxidation of methane supports high biomass and diversity of chemosynthetic communities. Bare sediments interspersed with heterogeneous chemosynthetic assemblages of mytilid mussels, vesicomyid clams and siboglinid tubeworms form a complex seep ecosystem. To better understand if benthic bacterial communities reflect the patchy distribution of chemosynthetic fauna, all major chemosynthetic habitats at REGAB were investigated using an interdisciplinary approach combining pore water geochemistry, in situ quantification of fluxes and consumption of methane, as well as bacterial community fingerprinting. This study revealed that sediments populated by different fauna assemblages show distinct biogeochemical activities and are associated with distinct sediment bacterial communities. The methane consumption rates and methane effluxes ranged over one to two orders of magnitude across habitats, and reached highest values at the mussel habitat, which hosted a different bacterial community compared to the other habitats. Clam assemblages had a profound impact on the sediment geochemistry, but less so on the bacterial community structure. Moreover, all clam assemblages at REGAB were restricted to sediments characterized by complete methane consumption in the seafloor, and intermediate biogeochemical activity. Overall, variations in the sediment geochemistry were reflected in the distribution of both fauna and microbial communities; and were mostly determined by methane flux.
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Kawamoto, Yasutake, Hiromi Kato, Yuji Nagata et Jotaro Urabe. « Microbial communities developing within bulk sediments under fish carcasses on a tidal flat ». PLOS ONE 16, no 2 (25 février 2021) : e0247220. http://dx.doi.org/10.1371/journal.pone.0247220.
Texte intégralRésumé :
Animal carcasses are often brought into tidal flats where they are at the boundary between terrestrial and marine ecosystems. Since these carcasses act as microhabitats with large amounts of energy and nutrients, they likely develop unique bacterial assemblages in the ambient sediment, which in turn may stimulate colonization of other organisms such as protozoans. However, little is known about the microbial assemblages colonized in sediment around animal carcasses in the tidal zone. Herein we examined the bacterial and ciliophoran assemblages developed in association with fish carcasses by incubating the carcasses in the Higashiyachi tidal flat (Sendai, Japan). We collected sediment samples at 2, 9, and 42 days of incubation and analyzed the bacterial and ciliophoran assemblages by 16S and 18S rRNA gene amplicon sequencing. We observed significant differences in the composition and relative abundance of bacterial and ciliophoran operational taxonomic units (OTUs) between the sediments with and without the carcasses. Our analyses suggest that these unique assemblages were created through the direct effects of the carcass and indirect effects through interactions between bacteria and ciliophorans. These results also suggest that animal carcasses developed a temporally unique microbial food web in the sediments close to the carcasses, although it disappeared for several weeks.
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Noble, Peter A., Jonas S. Almeida et Charles R. Lovell. « Application of Neural Computing Methods for Interpreting Phospholipid Fatty Acid Profiles of Natural Microbial Communities ». Applied and Environmental Microbiology 66, no 2 (1 février 2000) : 694–99. http://dx.doi.org/10.1128/aem.66.2.694-699.2000.
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ABSTRACT The microbial community compositions of surface and subsurface marine sediments and sediments lining burrows of marine polychaetes and hemichordates from the North Inlet estuary (near Georgetown, S.C.) were analyzed by comparing ester-linked phospholipid fatty acid (PLFA) profiles with a back-propagating neural network (NN). The NNs were trained to relate PLFA inputs to sediment type outputs (e.g., surface, subsurface, and burrow lining) and worm species (e.g., Notomastus lobatus, Balanoglossus aurantiacus, andBranchyoasychus americana). Sensitivity analysis was used to determine which of the 60 PLFAs significantly contributed to training the NN. The NN architecture was optimized by changing the number of hidden neurons and calculating the cross-validation error between predicted and actual outputs of training and test data. The optimal NN architecture was found to be four hidden neurons with 60-input neurons representing the 60 PLFAs, and four output neurons coding for both sediment types and worm species. Comparison of cross-validation results using NNs and linear discriminant analysis (LDA) revealed that NNs had significantly fewer incorrect classifications (2.7%) than LDA (8.4%). For the NN cross-validation, both sediment type and worm species had 3 incorrect classifications out of 112. For the LDA cross-validation, sediment type and worm species had 7 and 12 incorrect classifications out of 112, respectively. Sensitivity analysis of the trained NNs revealed that 17 fatty acids explained 50% of variability in the data set. These PLFAs were highly different among sediments and burrow types, indicating significant differences in the microbiota.
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Ettinger, Cassandra L., Susan L. Williams, Jessica M. Abbott, John J. Stachowicz et Jonathan A. Eisen. « Microbiome succession during ammonification in eelgrass bed sediments ». PeerJ 5 (16 août 2017) : e3674. http://dx.doi.org/10.7717/peerj.3674.
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BackgroundEelgrass (Zostera marina) is a marine angiosperm and foundation species that plays an important ecological role in primary production, food web support, and elemental cycling in coastal ecosystems. As with other plants, the microbial communities living in, on, and near eelgrass are thought to be intimately connected to the ecology and biology of eelgrass. Here we characterized the microbial communities in eelgrass sediments throughout an experiment to quantify the rate of ammonification, the first step in early remineralization of organic matter, also known as diagenesis, from plots at a field site in Bodega Bay, CA.MethodsSediment was collected from 72 plots from a 15 month long field experiment in which eelgrass genotypic richness and relatedness were manipulated. In the laboratory, we placed sediment samples (n = 4 per plot) under a N2atmosphere, incubated them atin situtemperatures (15 °C) and sampled them initially and after 4, 7, 13, and 19 days to determine the ammonification rate. Comparative microbiome analysis using high throughput sequencing of 16S rRNA genes was performed on sediment samples taken initially and at seven, 13 and 19 days to characterize changes in the relative abundances of microbial taxa throughout ammonification.ResultsWithin-sample diversity of the sediment microbial communities across all plots decreased after the initial timepoint using both richness based (observed number of OTUs, Chao1) and richness and evenness based diversity metrics (Shannon, Inverse Simpson). Additionally, microbial community composition changed across the different timepoints. Many of the observed changes in relative abundance of taxonomic groups between timepoints appeared driven by sulfur cycling with observed decreases in predicted sulfur reducers (Desulfobacterales) and corresponding increases in predicted sulfide oxidizers (Thiotrichales). None of these changes in composition or richness were associated with variation in ammonification rates.DiscussionOur results showed that the microbiome of sediment from different plots followed similar successional patterns, which we infer to be due to changes related to sulfur metabolism. These large changes likely overwhelmed any potential changes in sediment microbiome related to ammonification rate. We found no relationship between eelgrass presence or genetic composition and the microbiome. This was likely due to our sampling of bulk sediments to measure ammonification rates rather than sampling microbes in sediment directly in contact with the plants and suggests that eelgrass influence on the sediment microbiome may be limited in spatial extent. More in-depth functional studies associated with eelgrass microbiome will be required in order to fully understand the implications of these microbial communities in broader host-plant and ecosystem functions (e.g., elemental cycling and eelgrass-microbe interactions).
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Navarrete-Euan, Herón, Zuemy Rodríguez-Escamilla, Ernesto Pérez-Rueda, Karla Escalante-Herrera et Mario Alberto Martínez-Núñez. « Comparing Sediment Microbiomes in Contaminated and Pristine Wetlands along the Coast of Yucatan ». Microorganisms 9, no 4 (20 avril 2021) : 877. http://dx.doi.org/10.3390/microorganisms9040877.
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Microbial communities are important players in coastal sediments for the functioning of the ecosystem and the regulation of biogeochemical cycles. They also have great potential as indicators of environmental perturbations. To assess how microbial communities can change their composition and abundance along coastal areas, we analyzed the composition of the microbiome of four locations of the Yucatan Peninsula using 16S rRNA gene amplicon sequencing. To this end, sediment from two conserved (El Palmar and Bocas de Dzilam) and two contaminated locations (Sisal and Progreso) from the coast northwest of the Yucatan Peninsula in three different years, 2017, 2018 and 2019, were sampled and sequenced. Microbial communities were found to be significantly different between the locations. The most noticeable difference was the greater relative abundance of Planctomycetes present at the conserved locations, versus FBP group found with greater abundance in contaminated locations. In addition to the difference in taxonomic groups composition, there is a variation in evenness, which results in the samples of Bocas de Dzilam and Progreso being grouped separately from those obtained in El Palmar and Sisal. We also carry out the functional prediction of the metabolic capacities of the microbial communities analyzed, identifying differences in their functional profiles. Our results indicate that landscape of the coastal microbiome of Yucatan sediment shows changes along the coastline, reflecting the constant dynamics of coastal environments and their impact on microbial diversity.
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Frischer, Marc E., Jean M. Danforth, Michele A. Newton Healy et F. Michael Saunders. « Whole-Cell versus Total RNA Extraction for Analysis of Microbial Community Structure with 16S rRNA-Targeted Oligonucleotide Probes in Salt Marsh Sediments ». Applied and Environmental Microbiology 66, no 7 (1 juillet 2000) : 3037–43. http://dx.doi.org/10.1128/aem.66.7.3037-3043.2000.
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ABSTRACT rRNA-targeted oligonucleotide probes have become powerful tools for describing microbial communities, but their use in sediments remains difficult. Here we describe a simple technique involving homogenization, detergents, and dispersants that allows the quantitative extraction of cells from formalin-preserved salt marsh sediments. Resulting cell extracts are amenable to membrane blotting and hybridization protocols. Using this procedure, the efficiency of cell extraction was high (95.7% � 3.7% [mean � standard deviation]) relative to direct DAPI (4′,6′-diamidino-2-phenylindole) epifluorescence cell counts for a variety of salt marsh sediments. To test the hypothesis that cells were extracted without phylogenetic bias, the relative abundance (depth distribution) of five major divisions of the gram-negative mesophilic sulfate-reducing delta proteobacteria were determined in sediments maintained in a tidal mesocosm system. A suite of six 16S rRNA-targeted oligonucleotide probes were utilized. The apparent structure of sulfate-reducing bacteria communities determined from whole-cell and RNA extracts were consistent with each other (r 2 = 0.60), indicating that the whole-cell extraction and RNA extraction hybridization approaches for describing sediment microbial communities are equally robust. However, the variability associated with both methods was high and appeared to be a result of the natural heterogeneity of sediment microbial communities and methodological artifacts. The relative distribution of sulfate-reducing bacteria was similar to that observed in natural marsh systems, providing preliminary evidence that the mesocosm systems accurately simulate native marsh systems.
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Hullar, Meredith A. J., Louis A. Kaplan et David A. Stahl. « Recurring Seasonal Dynamics of Microbial Communities in Stream Habitats ». Applied and Environmental Microbiology 72, no 1 (janvier 2006) : 713–22. http://dx.doi.org/10.1128/aem.72.1.713-722.2006.
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ABSTRACT Recurring seasonal patterns of microbial distribution and abundance in three third-order temperate streams within the southeast Pennsylvania Piedmont were observed over 4 years. Populations associated with streambed sediments and rocks (epilithon) were identified using terminal restriction length polymorphism (tRFLP) and sequencing of 16S rRNA genes selectively amplified with primers for the bacterial domain. Analyses of the relative magnitudes of tRFLP peak areas by using nonmetric multidimensional scaling resolved clear seasonal trends in epilithic and sediment populations. Oscillations between two dominant groups of epilithic genotypes, explaining 86% of the seasonal variation in the data set, were correlated with temperature and dissolved organic carbon. Sequences affiliated with epilithic phototrophs (cyanobacteria and diatom chloroplasts), a Rhodoferax sp., and a Bacillus species clustered in the summer, whereas sequences most closely related to “Betaproteobacteria” (putative Burkholderia sp.), and a putative cyanobacterium clustered in the fall/spring. The sediment genotypes also clustered into two groups, and these explained 85% of seasonal variation but correlated only with temperature. A summer tRFLP pattern was characterized by prevalence of “Betaproteobacteria,” “Gammaproteobacteria,” and a Bacillus sp., whereas the winter/spring pattern was characterized by phylotypes most closely related to “Firmicutes,” “Gammaproteobacteria,” and “Nitrospirae.” A close association between these headwater streams and their watersheds was suggested by the recovery of sequences related to microbial populations provisionally attributed to not only freshwaters but also terrestrial habitats.
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Kurtz, Janis C., Richard Devereux, Tamar Barkay et Robert B. Jonas. « Evaluation of sediment slurry microcosms for modeling microbial communities in estuarine sediments ». Environmental Toxicology and Chemistry 17, no 7 (juillet 1998) : 1274–81. http://dx.doi.org/10.1002/etc.5620170712.
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Matsui, George Y., David B. Ringelberg et Charles R. Lovell. « Sulfate-Reducing Bacteria in Tubes Constructed by the Marine Infaunal Polychaete Diopatra cuprea ». Applied and Environmental Microbiology 70, no 12 (décembre 2004) : 7053–65. http://dx.doi.org/10.1128/aem.70.12.7053-7065.2004.
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ABSTRACT Marine infaunal burrows and tubes greatly enhance solute transport between sediments and the overlying water column and are sites of elevated microbial activity. Biotic and abiotic controls of the compositions and activities of burrow and tube microbial communities are poorly understood. The microbial communities in tubes of the marine infaunal polychaete Diopatria cuprea collected from two different sediment habitats were examined. The bacterial communities in the tubes from a sandy sediment differed from those in the tubes from a muddy sediment. The difference in community structure also extended to the sulfate-reducing bacterial (SRB) assemblage, although it was not as pronounced for this functional group of species. PCR-amplified 16S rRNA gene sequences recovered from Diopatra tube SRB by clonal library construction and screening were all related to the family Desulfobacteriaceae. This finding was supported by phospholipid fatty acid analysis and by hybridization of 16S rRNA probes specific for members of the genera Desulfosarcina, Desulfobacter, Desulfobacterium, Desulfobotulus, Desulfococcus, and Desulfovibrio and some members of the genera Desulfomonas, Desulfuromonas, and Desulfomicrobium with 16S rRNA gene sequences resolved by denaturing gradient gel electrophoresis. Two of six SRB clones from the clone library were not detected in tubes from the sandy sediment. The habitat in which the D. cuprea tubes were constructed had a strong influence on the tube bacterial community as a whole, as well as on the SRB assemblage.
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Liu, Qian, Junnan Li, Hongwei Shan et Yicheng Xie. « Metagenomic Insights into the Structure of Microbial Communities Involved in Nitrogen Cycling in Two Integrated Multitrophic Aquaculture (IMTA) Ponds ». Journal of Marine Science and Engineering 10, no 2 (27 janvier 2022) : 171. http://dx.doi.org/10.3390/jmse10020171.
Texte intégralRésumé :
The microbial structure and metabolic potential, particularly with regard to nitrogen (N) cycling, in integrated multitrophic aquaculture (IMTA) ponds with shrimp remain unclear. In this study, an analysis of microbial community taxonomic diversity and a metagenomic analysis of N-related genes were performed in a shrimp-crab pond (Penaeus japonicus-Portunus trituberculatus, SC) and a shrimp-crab-clam pond (P. japonicus-P. trituberculatus-Sinonovacula constricta, SCC) to evaluate microbial structure and N transformation capacities in these two shrimp IMTA ponds. The composition of the microbial communities was similar between SC and SCC, but the water and sediments shared few common members in either pond. The relative abundances of N cycling genes were significantly higher in sediment than in water in both SC and SCC, except for assimilatory nitrate reduction genes. The main drivers of the differences in the relative abundances of N cycling genes in SC and SCC were salinity and pH in water and the NO2− and NH4+ contents of pore water in sediment. These results indicate that the coculture of S. constricta in a shrimp-crab pond may result in decreased N cycling in sediment. The reduced N flux in the shrimp IMTA ponds primarily originates within the sediment, except for assimilatory nitrate reduction.
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Federle, Thomas W., Robert J. Livingston, Loretta E. Wolfe et David C. White. « A quantitative comparison of microbial community structure of estuarine sediments from microcosms and the field ». Canadian Journal of Microbiology 32, no 4 (1 avril 1986) : 319–25. http://dx.doi.org/10.1139/m86-063.
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Estuarine soft-bottom sediments in microcosms and the field were compared with regard to microbial community structure. Community structure was determined by analyzing the fatty acids derived from the microbial lipids in the sediments. Fatty acid profiles were compared using a multivariate statistical approach. Experiments were performed using sediments from St. George Sound and Apalachicola Bay, Florida. The community structure of St. George Sound sediments was apparently controlled by epibenthic predators. In Apalachicola Bay, the dominant influences were physical factors related to the flow of the Apalachicola River. In the St. George Sound experiment, microbial communities in the microcosms differed from those in the field after only 2 weeks, and the degree of this difference increased substantially as time progressed. In the Apalachicola Bay experiment, although microbial communities in the microcosms were detectably different from those in the field, the degree of this difference was not large nor did it increase with time. This differential behavior of sediment communities from different sites may be related to the different ecological factors regulating community composition at these sites.
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Angermeyer, Angus, Sarah C. Crosby et Julie A. Huber. « Salt marsh sediment bacterial communities maintain original population structure after transplantation across a latitudinal gradient ». PeerJ 6 (1 mai 2018) : e4735. http://dx.doi.org/10.7717/peerj.4735.
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Dispersal and environmental selection are two of the most important factors that govern the distributions of microbial communities in nature. While dispersal rates are often inferred by measuring the degree to which community similarity diminishes with increasing geographic distance, determining the extent to which environmental selection impacts the distribution of microbes is more complex. To address this knowledge gap, we performed a large reciprocal transplant experiment to simulate the dispersal of US East Coast salt marsh Spartina alterniflora rhizome-associated microbial sediment communities across a latitudinal gradient and determined if any shifts in microbial community composition occurred as a result of the transplantation. Using bacterial 16S rRNA gene sequencing, we did not observe large-scale changes in community composition over a five-month S. alterniflora summer growing season and found that transplanted communities more closely resembled their origin sites than their destination sites. Furthermore, transplanted communities grouped predominantly by region, with two sites from the north and three sites to the south hosting distinct bacterial taxa, suggesting that sediment communities transplanted from north to south tended to retain their northern microbial distributions, and south to north maintained a southern distribution. A small number of potential indicator 16S rRNA gene sequences had distributions that were strongly correlated to both temperature and nitrogen, indicating that some organisms are more sensitive to environmental factors than others. These results provide new insight into the microbial biogeography of salt marsh sediments and suggest that established bacterial communities in frequently-inundated environments may be both highly resistant to invasion and resilient to some environmental shifts. However, the extent to which environmental selection impacts these communities is taxon specific and variable, highlighting the complex interplay between dispersal and environmental selection for microbial communities in nature.
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Weingarten, Eric A., Lauren A. Lawson et Colin R. Jackson. « The Saltpan Microbiome Is Structured by Sediment Depth and Minimally Influenced by Variable Hydration ». Microorganisms 8, no 4 (8 avril 2020) : 538. http://dx.doi.org/10.3390/microorganisms8040538.
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Saltpans are a class of ephemeral wetland characterized by alternating periods of inundation, rising salinity, and desiccation. We obtained soil cores from a saltpan on the Mississippi Gulf coast in both the inundated and desiccated state. The microbiomes of surface and 30 cm deep sediment were determined using Illumina sequencing of the V4 region of the 16S rRNA gene. Bacterial and archaeal community composition differed significantly between sediment depths but did not differ between inundated and desiccated states. Well-represented taxa included marine microorganisms as well as multiple halophiles, both observed in greater proportions in surface sediment. Functional inference of metagenomic data showed that saltpan sediments in the inundated state had greater potential for microbial activity and that several energetic and degradation pathways were more prevalent in saltpan sediment than in nearby tidal marsh sediment. Microbial communities within saltpan sediments differed in composition from those in adjacent freshwater and brackish marshes. These findings indicate that the bacterial and archaeal microbiomes of saltpans are highly stratified by sediment depth and are only minimally influenced by changes in hydration. The surface sediment community is likely isolated from the shallow subsurface community by compaction, with the microbial community dominated by marine and terrestrial halophiles.
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Reed, David W., Yoshiko Fujita, Mark E. Delwiche, D. Brad Blackwelder, Peter P. Sheridan, Takashi Uchida et Frederick S. Colwell. « Microbial Communities from Methane Hydrate-Bearing Deep Marine Sediments in a Forearc Basin ». Applied and Environmental Microbiology 68, no 8 (août 2002) : 3759–70. http://dx.doi.org/10.1128/aem.68.8.3759-3770.2002.
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ABSTRACT Microbial communities in cores obtained from methane hydrate-bearing deep marine sediments (down to more than 300 m below the seafloor) in the forearc basin of the Nankai Trough near Japan were characterized with cultivation-dependent and -independent techniques. Acridine orange direct count data indicated that cell numbers generally decreased with sediment depth. Lipid biomarker analyses indicated the presence of viable biomass at concentrations greater than previously reported for terrestrial subsurface environments at similar depths. Archaeal lipids were more abundant than bacterial lipids. Methane was produced from both acetate and hydrogen in enrichments inoculated with sediment from all depths evaluated, at both 10 and 35°C. Characterization of 16S rRNA genes amplified from the sediments indicated that archaeal clones could be discretely grouped within the Euryarchaeota and Crenarchaeota domains. The bacterial clones exhibited greater overall diversity than the archaeal clones, with sequences related to the Bacteroidetes, Planctomycetes, Actinobacteria, Proteobacteria, and green nonsulfur groups. The majority of the bacterial clones were either members of a novel lineage or most closely related to uncultured clones. The results of these analyses suggest that the microbial community in this environment is distinct from those in previously characterized methane hydrate-bearing sediments.
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Bi, Sheng, Han Lai, Dingli Guo, Xuange Liu, Gongpei Wang, Xiaoli Chen, Shuang Liu, Huadong Yi, Yuqin Su et Guifeng Li. « The Characteristics of Intestinal Bacterial Community in Three Omnivorous Fishes and Their Interaction with Microbiota from Habitats ». Microorganisms 9, no 10 (9 octobre 2021) : 2125. http://dx.doi.org/10.3390/microorganisms9102125.
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Artificial fishery habitats have been extensively used for fishery resource protection and water habitat restoration, and they could attract a large number of omnivorous fishes to gather together. This study intended to reveal the relationship between bacterial communities in the habitats (water and sediment) and intestines of omnivorous fishes (Oreochromis mossambicus, Toxabramis houdemeri and Hemiculter leucisculus). Therefore, we investigated the bacterial communities of samples collected from intestines, water, and sediments in artificial fishery habitats via 16S rRNA metabarcoding high-throughput sequencing technology. The results showed that there were significant differences in the composition, core indicators, diversity and prediction functions in water, sediments, and intestinal microbial communities of the three omnivorous fish. The microbial diversities were significantly higher in habitats than in intestines. The analysis of similarity (ANOSIM) and nonmetric multidimensional scaling (NMDS) results indicated that the intestine microbial communities (T. houdemeri and H. leucisculus) were more similar to the water microbiota, but the intestine microbial communities (O. mossambicus) were more similar to the sediments. Source tracking analysis also confirmed that the contribution of habitat characteristics to omnivorous fish intestinal microorganisms was different; the sediment had a greater contribution than water to the intestinal microbiota of O. mossambicus, which was consistent with their benthic habit. Moreover, the functional prediction results showed that there were unique core indicators and functions between the bacterial community of habitats and intestines. Altogether, these results can enhance our understanding of the bacterial composition and functions about omnivorous fish intestines and their living with habitats, which have provided new information for the ecological benefits of artificial fishery habitats from the perspective of bacterial ecology and contributed to apply artificial fishery habitats in more rivers.
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Pham, Huynh A., Carolyn E. Oldham et Jason J. Plumb. « The Diversity of Benthic Microorganisms in Acidic Mine Lake Sediments ». Advanced Materials Research 20-21 (juillet 2007) : 489–92. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.489.
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The sediment microbial communities of a disused coal mine lake, Lake Kepwari (pH~4.5-5) were studied to understand how the natural microbial processes in an oligotrophic acidic mine lake system influence the iron and sulphur cycles. Most probable number (MPN) viable counts were used to enumerate the benthic bacteria at different depths. MPN results revealed an abundance of bacteria that were capable of growing in sulphate reducing medium with numbers in the range of 1 × 107 – 1 × 108 cells.g-1 of wet sediment. In contrast, MPN results showed much lower numbers of bacteria that were capable of growing in ferric reducing medium with 1 × 102 – 2 × 103 cells.g-1 of wet sediment detected. Serial decimal dilution cultures were used to isolate pure strains of benthic bacteria. Strains HP1, HP2 and HP3 were isolated from benthic lake sediments at 18 m, 0 m and 10 m water depths respectively. 16S rRNA gene sequence analysis of strain HP1 showed that the strain belonged to the genus Enterobacter, strain HP2 belonged to the Order Rhizobiales and strain HP3 belonged to the sub-order Micrococcineae. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene fragments was used to profile the diversity of the benthic microbial communities at different depths. DGGE profiling of benthic sediments revealed that sediments contained mostly members of the Proteobacteria, Actinobacteria and Firmicutes phyla.
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Teske, A., A. Durbin, K. Ziervogel, C. Cox et C. Arnosti. « Microbial Community Composition and Function in Permanently Cold Seawater and Sediments from an Arctic Fjord of Svalbard ». Applied and Environmental Microbiology 77, no 6 (21 janvier 2011) : 2008–18. http://dx.doi.org/10.1128/aem.01507-10.
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ABSTRACTHeterotrophic microbial communities in seawater and sediments metabolize much of the organic carbon produced in the ocean. Although carbon cycling and preservation depend critically on the capabilities of these microbial communities, their compositions and capabilities have seldom been examined simultaneously at the same site. To compare the abilities of seawater and sedimentary microbial communities to initiate organic matter degradation, we measured the extracellular enzymatic hydrolysis rates of 10 substrates (polysaccharides and algal extracts) in surface seawater and bottom water as well as in surface and anoxic sediments of an Arctic fjord. Patterns of enzyme activities differed between seawater and sediments, not just quantitatively, in accordance with higher cell numbers in sediments, but also in their more diversified enzyme spectrum. Sedimentary microbial communities hydrolyzed all of the fluorescently labeled polysaccharide and algal extracts, in most cases at higher rates in subsurface than surface sediments. In seawater, in contrast, only 5 of the 7 polysaccharides and 2 of the 3 algal extracts were hydrolyzed, and hydrolysis rates in surface and deepwater were virtually identical. To compare bacterial communities, 16S rRNA gene clone libraries were constructed from the same seawater and sediment samples; they diverged strongly in composition. Thus, the broader enzymatic capabilities of the sedimentary microbial communities may result from the compositional differences between seawater and sedimentary microbial communities, rather than from gene expression differences among compositionally similar communities. The greater number of phylum- and subphylum-level lineages and operational taxonomic units in sediments than in seawater samples may reflect the necessity of a wider range of enzymatic capabilities and strategies to access organic matter that has already been degraded during passage through the water column. When transformations of marine organic matter are considered, differences in community composition and their different abilities to access organic matter should be taken into account.
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Lozupone, Catherine, et Rob Knight. « UniFrac : a New Phylogenetic Method for Comparing Microbial Communities ». Applied and Environmental Microbiology 71, no 12 (décembre 2005) : 8228–35. http://dx.doi.org/10.1128/aem.71.12.8228-8235.2005.
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ABSTRACT We introduce here a new method for computing differences between microbial communities based on phylogenetic information. This method, UniFrac, measures the phylogenetic distance between sets of taxa in a phylogenetic tree as the fraction of the branch length of the tree that leads to descendants from either one environment or the other, but not both. UniFrac can be used to determine whether communities are significantly different, to compare many communities simultaneously using clustering and ordination techniques, and to measure the relative contributions of different factors, such as chemistry and geography, to similarities between samples. We demonstrate the utility of UniFrac by applying it to published 16S rRNA gene libraries from cultured isolates and environmental clones of bacteria in marine sediment, water, and ice. Our results reveal that (i) cultured isolates from ice, water, and sediment resemble each other and environmental clone sequences from sea ice, but not environmental clone sequences from sediment and water; (ii) the geographical location does not correlate strongly with bacterial community differences in ice and sediment from the Arctic and Antarctic; and (iii) bacterial communities differ between terrestrially impacted seawater (whether polar or temperate) and warm oligotrophic seawater, whereas those in individual seawater samples are not more similar to each other than to those in sediment or ice samples. These results illustrate that UniFrac provides a new way of characterizing microbial communities, using the wealth of environmental rRNA sequences, and allows quantitative insight into the factors that underlie the distribution of lineages among environments.
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Neff, Alexis N., Dean M. DeNicola et Chris Maltman. « Passive Treatment for Acid Mine Drainage Partially Restores Microbial Community Structure in Different Stream Habitats ». Water 13, no 22 (22 novembre 2021) : 3300. http://dx.doi.org/10.3390/w13223300.
Texte intégralRésumé :
The assessment of the degree to which biological communities in streams impaired by acid mine drainage (AMD) are restored by passive treatment has focused primarily on eukaryotic-cell organisms and microbial processes. The responses of microbial community structure to passive treatment have received much less attention, even though functional processes such as nutrient cycling and organic matter decomposition depend on taxonomic composition. Our objective was to determine the degree to which passive treatment restored microbial communities in three types of habitats: aqueous, leaf, and sediment. To assess their recovery, we compared the community composition in these habitats based on 16S rRNA gene sequencing at three different stream sites: an untreated AMD site (U), a remediated site below AMD passive treatment (T), and an unimpaired reference site (R). The acidity, conductivity, and soluble metal concentrations at T were found to be elevated compared to R, but generally 1–2 orders of magnitude less than at U. Microbial community composition was found to be synergistically affected by habitat type and AMD impact, with the similarity among communities in the three habitats increasing with the severity of the AMD. Sediment- and leaf-associated microbial communities at U were characterized by taxa that are tolerant to severe AMD. The absence of the nitrogen oxidizing bacterium Nitrospira in sediment communities at T and U was found to correspond to higher NH4+ concentrations compared to R, possibly because of the presence of iron oxyhydroxide precipitate. In contrast, the microbial composition was found to be similar between the T and R sites for both aqueous and leaf communities, indicating that passive treatment was more able to restore these communities to the reference condition than sediment communities. The remediation of AMD streams should consider the habitat-specific responses of microbial community composition and be guided by future studies that empirically couple changes in taxonomic composition to measured functional processes.
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Cui, Guojie, Jun Li, Zhaoming Gao et Yong Wang. « Spatial variations of microbial communities in abyssal and hadal sediments across the Challenger Deep ». PeerJ 7 (17 mai 2019) : e6961. http://dx.doi.org/10.7717/peerj.6961.
Texte intégralRésumé :
Microbial communities in hadal sediments are least explored in hadal zone (>6,000 m), especially in the Challenger Deep with high pressure (∼110 M pa at the bottom). In this study, we investigated the microbial communities in the sediments of the slope and trench-axis bottom of the Challenger Deep in the Mariana Trench. Classification of the reads of the 16S rRNA gene amplicons showed vertical distribution of prokaryotic microbial inhabitants from the surface to up to 60 centimeter below surface floor (cmbsf). The most dominant phyla were Proteobacteria, Chloroflexi, Actinobacteria, Planctomycetes and candidate phyla Patescibacteria and Marinimicrobia. Distinct dominant groups in the microbial communities were observed in trench-axis sediment (water depth >8,600 m), compared to the slopes of the Challenger Deep. A sampling site at the northern slope was enriched with archaea from mesophilic Euryarchaeota Marine Group II (MGII) as a biomarker of specific geochemical setting. Among archaeal community, Thaumarchaeota represented byNitrosopumiluswere dominant in the upper layers and diminished drastically in the deeper layers. “Ca. Woesearchaeota”, however, became the dominant group in the deeper layers. Overall, our study provides a better understanding on the pattern of the microbial communities in the deepest hadal sediments on Earth, and highlights the extraordinary diversity still waiting to be discovered.
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Sauer, Hailey M., Trinity L. Hamilton, Rika E. Anderson, Charles E. Umbanhowar et Adam J. Heathcote. « Diversity and distribution of sediment bacteria across an ecological and trophic gradient ». PLOS ONE 17, no 3 (21 mars 2022) : e0258079. http://dx.doi.org/10.1371/journal.pone.0258079.
Texte intégralRésumé :
The microbial communities of lake sediments have the potential to serve as valuable bioindicators and integrators of watershed land-use and water quality; however, the relative sensitivity of these communities to physio-chemical and geographical parameters must be demonstrated at taxonomic resolutions that are feasible by current sequencing and bioinformatic approaches. The geologically diverse and lake-rich state of Minnesota (USA) is uniquely situated to address this potential because of its variability in ecological region, lake type, and watershed land-use. In this study, we selected twenty lakes with varying physio-chemical properties across four ecological regions of Minnesota. Our objectives were to (i) evaluate the diversity and composition of the bacterial community at the sediment-water interface and (ii) determine how lake location and watershed land-use impact aqueous chemistry and influence bacterial community structure. Our 16S rRNA amplicon data from lake sediment cores, at two depth intervals, data indicate that sediment communities are more likely to cluster by ecological region rather than any individual lake properties (e.g., trophic status, total phosphorous concentration, lake depth). However, composition is tied to a given lake, wherein samples from the same core were more alike than samples collected at similar depths across lakes. Our results illustrate the diversity within lake sediment microbial communities and provide insight into relationships between taxonomy, physicochemical, and geographic properties of north temperate lakes.
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Thureborn, Petter, Andrea Franzetti, Daniel Lundin et Sara Sjöling. « Reconstructing ecosystem functions of the active microbial community of the Baltic Sea oxygen depleted sediments ». PeerJ 4 (19 janvier 2016) : e1593. http://dx.doi.org/10.7717/peerj.1593.
Texte intégralRésumé :
Baltic Sea deep water and sediments hold one of the largest anthropogenically induced hypoxic areas in the world. High nutrient input and low water exchange result in eutrophication and oxygen depletion below the halocline. As a consequence at Landsort Deep, the deepest point of the Baltic Sea, anoxia in the sediments has been a persistent condition over the past decades. Given that microbial communities are drivers of essential ecosystem functions we investigated the microbial community metabolisms and functions of oxygen depleted Landsort Deep sediments by metatranscriptomics. Results show substantial expression of genes involved in protein metabolism demonstrating that the Landsort Deep sediment microbial community is active. Identified expressed gene suites of metabolic pathways with importance for carbon transformation including fermentation, dissimilatory sulphate reduction and methanogenesis were identified. The presence of transcripts for these metabolic processes suggests a potential for heterotrophic-autotrophic community synergism and indicates active mineralisation of the organic matter deposited at the sediment as a consequence of the eutrophication process. Furthermore, cyanobacteria, probably deposited from the water column, are transcriptionally active in the anoxic sediment at this depth. Results also reveal high abundance of transcripts encoding integron integrases. These results provide insight into the activity of the microbial community of the anoxic sediment at the deepest point of the Baltic Sea and its possible role in ecosystem functioning.
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Yasir, Muhammad, Arooj K. Qureshi et Esam I. Azhar. « 16S amplicon sequencing of microbial communities in enriched and non-enriched sediments of non-volcanic hot spring with temperature gradients ». PeerJ 9 (2 avril 2021) : e10995. http://dx.doi.org/10.7717/peerj.10995.
Texte intégralRésumé :
Microorganisms in geothermal springs can offer insights into the fundamental and applied study of extremophiles. However, low microbial abundance and culturing requirements limit the ability to analyze microbial diversity in these ecosystems. In this study, culture-dependent and culture-independent techniques were used to analyze sediment samples from the non-volcanic Tatta Pani hot springs in district Poonch of Azad Kashmir. Microbial composition, temperature gradient, and enrichment effects on rare taxa were evaluated. In total, 31 distinct bacterial phyla and 725 genera were identified from the non-enriched Tatta Pani hot spring sediment samples, and 33 distinct bacterial phyla and 890 genera from the enriched sediment samples. Unique phyla specimens from the enriched samples included Candidatus Cloacimonetes, Caldiserica, and Korarchaeota archaea. The enriched samples yielded specific microbiota including 805 bacteria and 42 archaea operational taxonomic units with 97% similarity, though decreased thermophilic microbiota were observed in the enriched samples. Microbial diversity increased as temperature decreased. Candidate novel species were isolated from the culture-dependent screening, along with several genera that were not found in the 16S amplicon sequencing data. Overall, the enriched sediments showed high microbial diversity but with adverse changes in the composition of relatively dominant bacteria. Metagenomic analyses are needed to study the diversity, phylogeny, and functional investigation of hot spring microbiota.
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Yang, Chu-Wen, Yi-En Chen et Bea-Ven Chang. « Microbial Communities Associated with Acetaminophen Biodegradation from Mangrove Sediment ». Sustainability 12, no 13 (4 juillet 2020) : 5410. http://dx.doi.org/10.3390/su12135410.
Texte intégralRésumé :
Acetaminophen (ACE) is a widely used medicine. Currently, concerns regarding its potential adverse effects on the environments are raised. The aim of this study was to evaluate ACE biodegradation in mangrove sediments under aerobic and anaerobic conditions. Three ACE biodegradation strategies in mangrove sediments were tested. The degradation half-lives (t1/2) of ACE in the sediments with spent mushroom compost under aerobic conditions ranged from 3.24 ± 0.16 to 6.25 ± 0.31 d. The degradation half-lives (t1/2) of ACE in sediments with isolated bacterial strains ranged from 2.54 ± 0.13 to 3.30 ± 0.17 d and from 2.62 ± 0.13 to 3.52 ± 0.17 d under aerobic and anaerobic conditions, respectively. The degradation half-lives (t1/2) of ACE in sediments amended with NaNO3, Na2SO4 and NaHCO3 under anaerobic conditions ranged from 1.16 ± 0.06 to 3.05 ± 0.15 d, 2.39 ± 0.12 to 3.84 ± 0.19 d and 2.79 ± 0.14 to 10.75 ± 0.53 d, respectively. The addition of the three electron acceptors enhanced ACE degradation in mangrove sediments, where NaNO3 yielded the best effects. Sixteen microbial genera were identified as the major members of microbial communities associated in anaerobic ACE degradation in mangrove sediments with addition of NaNO3 and Na2SO4. Three (Arthrobacter, Enterobacter and Bacillus) of the sixteen microbial genera were identified in the isolated ACE-degrading bacterial strains.
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Zhang, Zhimin, Qinghui Deng, Lingling Wan, Xiuyun Cao, Yiyong Zhou et Chunlei Song. « Bacterial Communities and Enzymatic Activities in Sediments of Long-Term Fish and Crab Aquaculture Ponds ». Microorganisms 9, no 3 (26 février 2021) : 501. http://dx.doi.org/10.3390/microorganisms9030501.
Texte intégralRésumé :
Aquaculture is among the most important and fastest growing agriculture sectors worldwide; however, it generates environmental impacts by introducing nutrient accumulations in ponds, which are possibly different and further result in complex biological processes in the sediments based on diverse farming practices. In this study, we investigated the effects of long-term farming practices of representative aquatic animals dominated by grass carp (GC, Ctenopharyngodon idella) or Chinese mitten crab (CMC, Eriocheir sinensis) on the bacterial community and enzyme activity of sediments from more than 15 years of aquaculture ponds, and the differences associated with sediment properties were explored in the two farming practices. Compared to CMC ponds, GC ponds had lower contents of TC, TN, and TP in sediments, and similar trends for sediment pH and moisture content. Sediment bacterial communities were significantly different between GC and CMC ponds, with higher bacterial richness and diversity in GC ponds. The bacterial communities among the pond sediments were closely associated with sediment pH, TC, and TN. Additionally, the results showed profoundly lower activities of β-1,4-glucosidase, leucine aminopeptidase, and phosphatase in the sediments of GC ponds than CMC ponds. Pearson’s correlation analysis further revealed strong positive correlations between the hydrolytic enzyme activities and nutrient concentrations among the aquaculture ponds, indicating microbial enzyme regulation response to sediment nutrient dynamics. Our study herein reveals that farming practices of fish and crab differently affect bacterial communities and enzymatic activities in pond sediments, suggesting nutrient-driven sediment biological processes in aquaculture ponds for different farming practices.
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Zeng, Jin, Liu-Yan Yang, Yi Liang, Jia-Yun Li, Lin Xiao, Li-Juan Jiang et Da-Yong Zhao. « Spatial distribution of bacterial communities in sediment of a eutrophic lake revealed by denaturing gradient gel electrophoresis and multivariate analysis ». Canadian Journal of Microbiology 54, no 12 (décembre 2008) : 1053–63. http://dx.doi.org/10.1139/w08-098.
Texte intégralRésumé :
Bacterial community structure and the effects of several environmental factors on the microbial community distribution were investigated in the sediment of the eutrophic Lake Xuanwu. Profiles of bacterial communities were generated using denaturing gradient gel electrophoresis (DGGE), and the results were interpreted with multivariate statistical analysis. Five major variables in sediment were examined in a principal component analysis, which indicates notable differences of physicochemical parameters among different sites of the lake. To assess changes in the genetic diversity of bacterial communities of different sampling sites, DGGE band patterns were analyzed by multidimensional scaling analysis, which indicated that sampling sites having similar environmental characteristics also have the similar microbial communities. Canonical correspondence analysis demonstrated that pH and redox potential had significant effects on the bacterial community composition in the sediments. Analysis of DNA sequences revealed that the dominant bacterial groups in Lake Xuanwu belonged to Proteobacteria , Actinobacteria , Verrucomicrobia , and Nitrospirae , which are commonly isolated from freshwater ecosystems.
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Gault, A. G., F. S. Islam, D. A. Polya, J. M. Charnock, C. Boothman, D. Chatterjee et J. R. Lloyd. « Microcosm depth profiles of arsenic release in a shallow aquifer, West Bengal ». Mineralogical Magazine 69, no 5 (octobre 2005) : 855–63. http://dx.doi.org/10.1180/0026461056950293.
Texte intégralRésumé :
AbstractArsenic mobilization and Fe(III) reduction in acetate-amended sediments collected from a range of depths from an aquifer with elevated groundwater arsenic concentrations in West Bengal were monitored over a 1 month period. Significant arsenic release was noted in sediment collected from 24 m and 45 m depth, with some Fe(III) reduction also observed in the 24 m sample. The structure of the microbial communities present in the sediments prior to incubation showed marked differences down the sediment column. Profiling of the microbial community in the 24 m and 45 m samples revealed a relatively complex make-up, with Acinetobacter species comprising the bulk of the 24 m sedimentary bacterial population, but no previously characterized As(V)-reducers were detected in either sample.
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De Schamphelaire, Liesje, Angela Cabezas, Massimo Marzorati, Michael W. Friedrich, Nico Boon et Willy Verstraete. « Microbial Community Analysis of Anodes from Sediment Microbial Fuel Cells Powered by Rhizodeposits of Living Rice Plants ». Applied and Environmental Microbiology 76, no 6 (22 janvier 2010) : 2002–8. http://dx.doi.org/10.1128/aem.02432-09.
Texte intégralRésumé :
ABSTRACT By placing the anode of a sediment microbial fuel cell (SMFC) in the rhizosphere of a rice plant, root-excreted rhizodeposits can be microbially oxidized with concomitant current generation. Here, various molecular techniques were used to characterize the composition of bacterial and archaeal communities on such anodes, as influenced by electrical circuitry, sediment matrix, and the presence of plants. Closed-circuit anodes in potting soil were enriched with Desulfobulbus-like species, members of the family Geobacteraceae, and as yet uncultured representatives of the domain Archaea.
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North, Nadia N., Sherry L. Dollhopf, Lainie Petrie, Jonathan D. Istok, David L. Balkwill et Joel E. Kostka. « Change in Bacterial Community Structure during In Situ Biostimulation of Subsurface Sediment Cocontaminated with Uranium and Nitrate ». Applied and Environmental Microbiology 70, no 8 (août 2004) : 4911–20. http://dx.doi.org/10.1128/aem.70.8.4911-4920.2004.
Texte intégralRésumé :
ABSTRACT Previous studies have demonstrated that metal-reducing microorganisms can effectively promote the precipitation and removal of uranium from contaminated groundwater. Microbial communities were stimulated in the acidic subsurface by pH neutralization and addition of an electron donor to wells. In single-well push-pull tests at a number of treated sites, nitrate, Fe(III), and uranium were extensively reduced and electron donors (glucose, ethanol) were consumed. Examination of sediment chemistry in cores sampled immediately adjacent to treated wells 3.5 months after treatment revealed that sediment pH increased substantially (by 1 to 2 pH units) while nitrate was largely depleted. A large diversity of 16S rRNA gene sequences were retrieved from subsurface sediments, including species from the α, β, δ, and γ subdivisions of the class Proteobacteria, as well as low- and high-G+C gram-positive species. Following in situ biostimulation of microbial communities within contaminated sediments, sequences related to previously cultured metal-reducing δ-Proteobacteria increased from 5% to nearly 40% of the clone libraries. Quantitative PCR revealed that Geobacter-type 16S rRNA gene sequences increased in biostimulated sediments by 1 to 2 orders of magnitude at two of the four sites tested. Evidence from the quantitative PCR analysis corroborated information obtained from 16S rRNA gene clone libraries, indicating that members of the δ-Proteobacteria subdivision, including Anaeromyxobacter dehalogenans-related and Geobacter-related sequences, are important metal-reducing organisms in acidic subsurface sediments. This study provides the first cultivation-independent analysis of the change in metal-reducing microbial communities in subsurface sediments during an in situ bioremediation experiment.
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Mosher, Jennifer J., Robert H. Findlay et Carl G. Johnston. « Physical and chemical factors affecting microbial biomass and activity in contaminated subsurface riverine sediments ». Canadian Journal of Microbiology 52, no 5 (1 mai 2006) : 397–403. http://dx.doi.org/10.1139/w05-144.
Texte intégralRésumé :
Over 80 years of direct discharge of industrial effluents into the Mahoning River, located in northeastern Ohio, USA, has led to the accumulation of a wide variety of pollutants within its sediments. This study examined the physical and chemical parameters, including lipophilic pollutants, affecting microbial activity and biomass in subsurface (10–40 cm horizon) sediments. Microbial biomass was higher in anthropogenically contaminated sediments, and step-wise linear regression showed that approximately 82% of the variation in microbial biomass could be explained by total hexane extractable hydrocarbons, sediment particle size, and water content. There was no correlation between microbial activity and biomass. Independent variables influencing anaerobic activity were temperature and water holding capacity. The results of this study indicate that freshwater, sedimentary anaerobic microbial communities respond to a range of environmental parameters, many of which influence subsurface river sediments, and that lipophilic pollutants, when present, can cause increases in total microbial biomass.Key words: microbial activity, microbial biomass, anaerobic sediments, PAH, metals.
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Starnawski, Piotr, Thomas Bataillon, Thijs J. G. Ettema, Lara M. Jochum, Lars Schreiber, Xihan Chen, Mark A. Lever et al. « Microbial community assembly and evolution in subseafloor sediment ». Proceedings of the National Academy of Sciences 114, no 11 (27 février 2017) : 2940–45. http://dx.doi.org/10.1073/pnas.1614190114.
Texte intégralRésumé :
Bacterial and archaeal communities inhabiting the subsurface seabed live under strong energy limitation and have growth rates that are orders of magnitude slower than laboratory-grown cultures. It is not understood how subsurface microbial communities are assembled and whether populations undergo adaptive evolution or accumulate mutations as a result of impaired DNA repair under such energy-limited conditions. Here we use amplicon sequencing to explore changes of microbial communities during burial and isolation from the surface to the >5,000-y-old subsurface of marine sediment and identify a small core set of mostly uncultured bacteria and archaea that is present throughout the sediment column. These persisting populations constitute a small fraction of the entire community at the surface but become predominant in the subsurface. We followed patterns of genome diversity with depth in four dominant lineages of the persisting populations by mapping metagenomic sequence reads onto single-cell genomes. Nucleotide sequence diversity was uniformly low and did not change with age and depth of the sediment. Likewise, there was no detectable change in mutation rates and efficacy of selection. Our results indicate that subsurface microbial communities predominantly assemble by selective survival of taxa able to persist under extreme energy limitation.