scholarly journals Iron and sulfate reduction structure microbial communities in (sub-)Antarctic sediments

2021 ◽  
Author(s):  
Lea C. Wunder ◽  
David A. Aromokeye ◽  
Xiuran Yin ◽  
Tim Richter-Heitmann ◽  
Graciana Willis-Poratti ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Sulfate Reduction ◽  
Marine Sediments ◽  
Iron Reduction ◽  
Environmental Changes ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Geochemical Parameters ◽  
Dissimilatory Iron Reduction ◽  
The Impact

AbstractPermanently cold marine sediments are heavily influenced by increased input of iron as a result of accelerated glacial melt, weathering, and erosion. The impact of such environmental changes on microbial communities in coastal sediments is poorly understood. We investigated geochemical parameters that shape microbial community compositions in anoxic surface sediments of four geochemically differing sites (Annenkov Trough, Church Trough, Cumberland Bay, Drygalski Trough) around South Georgia, Southern Ocean. Sulfate reduction prevails in Church Trough and iron reduction at the other sites, correlating with differing local microbial communities. Within the order Desulfuromonadales, the family Sva1033, not previously recognized for being capable of dissimilatory iron reduction, was detected at rather high relative abundances (up to 5%) while other members of Desulfuromonadales were less abundant (<0.6%). We propose that Sva1033 is capable of performing dissimilatory iron reduction in sediment incubations based on RNA stable isotope probing. Sulfate reducers, who maintain a high relative abundance of up to 30% of bacterial 16S rRNA genes at the iron reduction sites, were also active during iron reduction in the incubations. Thus, concurrent sulfate reduction is possibly masked by cryptic sulfur cycling, i.e., reoxidation or precipitation of produced sulfide at a small or undetectable pool size. Our results show the importance of iron and sulfate reduction, indicated by ferrous iron and sulfide, as processes that shape microbial communities and provide evidence for one of Sva1033’s metabolic capabilities in permanently cold marine sediments.

scholarly journals Impact of Soil Drying-Rewetting Stress on Microbial Communities and Activities and on Degradation of Two Crop Protection Products

2004 ◽  
Vol 70 (5) ◽  
pp. 2577-2587 ◽  
Author(s):  
Manuel Pesaro ◽  
Gilles Nicollier ◽  
Josef Zeyer ◽  
Franco Widmer
Keyword(s):  
16S Rrna ◽  
Microbial Communities ◽  
Stress Responses ◽  
Crop Protection ◽  
16S Rrna Genes ◽  
Cell Counting ◽  
Rrna Genes ◽  
Soil Dna ◽  
Degradation Rates ◽  
The Impact

ABSTRACT Prior to registration of crop protection products (CPPs) their persistence in soil has to be determined under defined conditions. For this purpose, soils are collected in the field and stored for up to 3 months prior to the tests. During storage, stresses like drying may induce changes in microbiological soil characteristics (MSCs) and thus may influence CPP degradation rates. We investigated the influence of soil storage-related stress on the resistance and resilience of different MSCs by assessing the impact of a single severe drying-rewetting cycle and by monitoring recovery from this event for 34 days. The degradation and mineralization of the fungicide metalaxyl-M and the insecticide lufenuron were delayed by factors of 1.5 to 5.4 in the dried and rewetted soil compared to the degradation and mineralization in an undisturbed reference. The microbial biomass, as estimated by direct cell counting and from the soil DNA content, decreased on average by 51 and 24%, respectively. The bulk microbial activities, as determined by measuring substrate-induced respiration and fluorescein diacetate hydrolysis, increased after rewetting and recovered completely within 6 days after reequilibration. The effects on Bacteria, Archaea, and Pseudomonas were investigated by performing PCR amplification of 16S rRNA genes and reverse-transcribed 16S rRNA, followed by restriction fragment length polymorphism (RFLP) and terminal RFLP (T-RFLP) fingerprinting. Statistical analyses of RFLP and T-RFLP profiles indicated that specific groups in the microbial community were sensitive to the stress. In addition, evaluation of rRNA genes and rRNA as markers for monitoring the stress responses of microbial communities revealed overall similar sensitivities. We concluded that various structural and functional MSCs were not resistant to drying-rewetting stress and that resilience depended strongly on the parameter investigated.

scholarly journals Viable cold-tolerant iron-reducing microorganisms in geographically-isolated subglacial environments

2016 ◽  
Author(s):  
Sophie L. Nixon ◽  
Jon Telling ◽  
Jemma L. Wadham ◽  
Charles S. Cockell
Keyword(s):  
Microbial Communities ◽  
Chemical Weathering ◽  
Iron Reduction ◽  
Enrichment Culture ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Microbial Iron Reduction ◽  
Cold Tolerant ◽  
Subglacial Environments ◽  
Geographically Isolated

Abstract. Subglacial environments are known to harbor metabolically-diverse microbial communities. These microbial communities drive chemical weathering of underlying bedrock and influence the geochemistry of glacial meltwaters. Despite its importance in weathering reactions, the microbial cycling of iron in subglacial environments, in particular the role of microbial iron reduction, is poorly understood. In this study we address the prevalence of viable iron-reducing microorganisms in subglacial sediments from five geographically isolated glaciers. Iron-reducing enrichment cultures were established with sediment from beneath Engabreen (Norway), Finsterwalderbreen (Svalbard), Leverett and Russell Glaciers (Greenland) and Lower Wright Glacier (Antarctica). Rates of iron reduction were higher at 4 °C compared with 15 °C in all but one duplicated second-generation enrichment culture, indicative of cold-tolerant and perhaps cold-adapted iron-reducers. Analysis of bacterial 16S rRNA genes indicate Desulfosporosinus were the dominant iron-reducing microorganisms in low-temperature Engabreen, Finsterwalderbreen and Lower Wright Glacier enrichments, and Geobacter dominated in Russell and Leverett enrichments. Results from this study suggest microbial iron reduction is widespread in subglacial environments, and may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

scholarly journals Community Structure of Ammonia-Oxidizing Bacteria within Anoxic Marine Sediments

2003 ◽  
Vol 69 (3) ◽  
pp. 1359-1371 ◽  
Author(s):  
Thomas E. Freitag ◽  
James I. Prosser
Keyword(s):  
16S Rrna ◽  
Microbial Communities ◽  
16S Rdna ◽  
Marine Sediments ◽  
Ammonia Oxidation ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Ammonia Oxidizing Bacteria ◽  
Anaerobic Oxidation ◽  
Banding Patterns

ABSTRACT The potential for oxidation of ammonia in anoxic marine sediments exists through anaerobic oxidation by Nitrosomonas-like organisms, utilizing nitrogen dioxide, coupling of nitrification, manganese reduction, and anaerobic oxidation of ammonium by planctomycetes (the Anammox process). Here we describe the presence of microbial communities with the potential to carry out these processes in a natural marine sediment system (Loch Duich, Scotland). Natural microbial communities of Planctomycetales-Verrucomicrobia and β- and γ-proteobacterial ammonia-oxidizing bacteria were characterized by analysis of 16S rRNA genes amplified using group-specific primers by PCR- and reverse transcription-PCR amplification of 16S rDNA and RNA, respectively. Amplification products were analyzed by sequencing of clones and by denaturant gradient gel electrophoresis (DGGE). Amplification of primers specific for Planctomycetales-Verrucomicrobia and β-proteobacterial ammonia-oxidizing bacteria generated products at all sampling sites and depths, but no product was generated using primers specific for γ-proteobacterial ammonia-oxidizing bacteria. 16S rDNA DGGE banding patterns indicated complex communities of β-proteobacterial ammonia-oxidizing bacteria in anoxic marine sediments. Phylogenetic analysis of sequences from clones and those excised from DGGE gels suggests dominance of Nitrosospira cluster 1-like organisms and of strains belonging to a novel cluster represented in dominant bands in 16S rRNA DGGE banding patterns. Their presence indicates a group of organisms closely related to recognized β-proteobacterial ammonia-oxidizing bacteria that may be selected in anoxic environments and may be capable of anoxic ammonia oxidation. Sequence analysis of planctomycete clone libraries and sequences excised from DGGE gels also demonstrated a diverse microbial community and suggested the presence of new subdivisions, but no sequence related to recognized Anammox organisms was detected.

scholarly journals Reef location has a greater impact than coral bleaching severity on the microbiome of Pocillopora acuta

Coral Reefs ◽  
2021 ◽  
Author(s):  
Emmanuelle S. Botté ◽  
Neal E. Cantin ◽  
Véronique J. L. Mocellin ◽  
Paul A. O’Brien ◽  
Melissa M. Rocker ◽  
...  
Keyword(s):  
Heat Stress ◽  
Microbial Communities ◽  
Coral Bleaching ◽  
Health Indicators ◽  
Amplicon Sequencing ◽  
Coral Community ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Bleaching Event ◽  
The Impact

AbstractCoral reefs are increasingly threatened by heat stress events leading to coral bleaching. In 2016, a mass bleaching event affected large parts of the Great Barrier Reef (GBR). Whilst bleaching severity and coral mortality are usually monitored throughout major bleaching events, other health indicators, such as changes in microbial partners, are rarely assessed. We examined the impact of the 2016 bleaching event on the composition of the microbial communities in the coral Pocillopora acuta at Havannah Island Pandora reef, separated by 12 km on the inshore central GBR. Corals experienced moderate heat stress (3.6 and 5.3 degree heating weeks), inducing major bleaching (30–60%) at the coral community level. Samples were partitioned according to Symbiodiniaceae densities into three bleaching severity categories (mild, moderate, and severe). Whilst Symbiodiniaceae densities were similar at both reef locations, sequencing of the Symbiodiniaceae ITS2 and prokaryotic 16S rRNA genes revealed that microbial communities were significantly different between reefs, but not according to bleaching severity. Symbiodiniaceae composition was dominated by the genus Cladocopium with low abundances of Durusdinium detected in moderately and severely bleached colonies at both sites, despite site-specific ITS2 profiles. Bacterial communities were dominated by Proteobacteria and were almost entirely lacking the common Pocilloporid associate Endozoicomonas regardless of bleaching severity. Strikingly, only 11.2% of the bacterial Amplicon Sequencing Variants (ASVs) were shared between sites. This reef specificity was driven by 165 ASVs, mainly from the family Rhodobacteraceae. Comparison with previous studies suggests that the moderate heat stress experienced on the central GBR in 2016 caused the near-complete absence of Endozoicomonas. Symbiodiniaceae and bacteria (particularly Rhodobacteraceae) can be vertically transmitted in P. acuta, and larval propagation can be spatially restricted for this brooding species. Our results demonstrate that, unlike bleaching severity, location-specific factors and species-specific life history traits might have been paramount in shaping the P. acuta microbiome.

scholarly journals Arable agriculture changes soil microbial communities in the South African Grassland Biome

2018 ◽  
Vol 114 (5/6) ◽  
Author(s):  
Gilbert Kamgan Nkuekam ◽  
Don A. Cowan ◽  
Angel Valverde
Keyword(s):  
Microbial Communities ◽  
Agricultural Soils ◽  
Soil Microbial Communities ◽  
Fungal Communities ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Soil Microbial Diversity ◽  
Soil Microbial ◽  
The Impact ◽  
Natural Grassland

Many studies, mostly in temperate regions of the northern hemisphere, have demonstrated that agricultural practices affect the composition and diversity of soil microbial communities. However, very little is known about the impact of agriculture on the microbial communities in other regions of the world, most particularly on the African continent. In this study, we used MiSeq amplicon sequencing of bacterial 16S rRNA genes and fungal ITS regions to characterise microbial communities in agricultural and natural grassland soils located in the Mpumalanga Province of South Africa. Nine soil chemical parameters were also measured to evaluate the effects of edaphic factors on microbial community diversity. Bacterial and fungal communities were significantly richer and more diverse in natural grassland than in agricultural soils. Microbial taxonomic composition was also significantly different between the two habitat types. The phylum Acidobacteria was significantly more abundant in natural grassland than in agricultural soils, while Actinobacteria and the family Nectriaceae showed the opposite pattern. Soil pH and phosphorus significantly influenced bacterial communities, whereas phosphorus and calcium influenced fungal communities. These findings may be interpreted as a negative impact of land-use change on soil microbial diversity and composition.

scholarly journals Viable cold-tolerant iron-reducing microorganisms in geographically diverse subglacial environments

2017 ◽  
Vol 14 (6) ◽  
pp. 1445-1455 ◽  
Author(s):  
Sophie L. Nixon ◽  
Jon P. Telling ◽  
Jemma L. Wadham ◽  
Charles S. Cockell
Keyword(s):  
Microbial Communities ◽  
Chemical Weathering ◽  
Iron Reduction ◽  
Enrichment Culture ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Iron Cycling ◽  
Microbial Iron Reduction ◽  
Cold Tolerant ◽  
Subglacial Environments

Abstract. Subglacial environments are known to harbour metabolically diverse microbial communities. These microbial communities drive chemical weathering of underlying bedrock and influence the geochemistry of glacial meltwater. Despite its importance in weathering reactions, the microbial cycling of iron in subglacial environments, in particular the role of microbial iron reduction, is poorly understood. In this study we address the prevalence of viable iron-reducing microorganisms in subglacial sediments from five geographically isolated glaciers. Iron-reducing enrichment cultures were established with sediment from beneath Engabreen (Norway), Finsterwalderbreen (Svalbard), Leverett and Russell glaciers (Greenland), and Lower Wright Glacier (Antarctica). Rates of iron reduction were higher at 4 °C compared with 15 °C in all but one duplicated second-generation enrichment culture, indicative of cold-tolerant and perhaps cold-adapted iron reducers. Analysis of bacterial 16S rRNA genes indicates Desulfosporosinus were the dominant iron-reducing microorganisms in low-temperature Engabreen, Finsterwalderbreen and Lower Wright Glacier enrichments, and Geobacter dominated in Russell and Leverett enrichments. Results from this study suggest microbial iron reduction is widespread in subglacial environments and may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

scholarly journals Microbial Communities from Methane Hydrate-Bearing Deep Marine Sediments in a Forearc Basin

2002 ◽  
Vol 68 (8) ◽  
pp. 3759-3770 ◽  
Author(s):  
David W. Reed ◽  
Yoshiko Fujita ◽  
Mark E. Delwiche ◽  
D. Brad Blackwelder ◽  
Peter P. Sheridan ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Marine Sediments ◽  
Methane Hydrate ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Forearc Basin ◽  
Subsurface Environments ◽  
Lipid Biomarker ◽  
Archaeal Lipids ◽  
Terrestrial Subsurface

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.

scholarly journals Diversity and Dynamics of Seaweed Associated Microbial Communities Inhabiting the Lagoon of Venice

2020 ◽  
Vol 8 (11) ◽  
pp. 1657
Author(s):  
Abdul-Salam Juhmani ◽  
Alessandro Vezzi ◽  
Mohammad Wahsha ◽  
Alessandro Buosi ◽  
Fabio De Pascale ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Bacterial Communities ◽  
Host Response ◽  
Environmental Parameters ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Nutrient Concentrations ◽  
Lagoon Of Venice ◽  
Anthropogenic Stressors ◽  
Rich Diversity

Seaweeds are a group of essential photosynthetic organisms that harbor a rich diversity of associated microbial communities with substantial functions related to host health and defense. Environmental and anthropogenic stressors may disrupt the microbial communities and their metabolic activity, leading to host physiological alterations that negatively affect seaweeds’ performance and survival. Here, the bacterial communities associated with one of the most common seaweed, Ulva laetevirens Areshough, were sampled over a year at three sites of the lagoon of Venice affected by different environmental and anthropogenic stressors. Bacterial communities were characterized through Illumina sequencing of the V4 hypervariable region of 16S rRNA genes. The study demonstrated that the seaweed associated bacterial communities at sites impacted by environmental stressors were host-specific and differed significantly from the less affected site. Furthermore, these communities were significantly distinct from those of the surrounding seawater. The bacterial communities’ composition was significantly correlated with environmental parameters (nutrient concentrations, dissolved oxygen saturation, and pH) across sites. This study showed that several more abundant bacteria on U. laetevirens at stressed sites belonged to taxa related to the host response to the stressors. Overall, environmental parameters and anthropogenic stressors were shown to substantially affect seaweed associated bacterial communities, which reflect the host response to environmental variations.

scholarly journals Habitat Elevation Shapes Microbial Community Composition and Alter the Metabolic Functions in Wild Sable (Martes zibellina) Guts

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 865
Author(s):  
Lantian Su ◽  
Xinxin Liu ◽  
Guangyao Jin ◽  
Yue Ma ◽  
Haoxin Tan ◽  
...  
Keyword(s):  
Microbial Community ◽  
Environmental Factors ◽  
Microbial Communities ◽  
Community Composition ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Functional Genes ◽  
Martes Zibellina ◽  
Clear Cutting ◽  
Metabolic Functions

In recent decades, wild sable (Carnivora Mustelidae Martes zibellina) habitats, which are often natural forests, have been squeezed by anthropogenic disturbances such as clear-cutting, tilling and grazing. Sables tend to live in sloped areas with relatively harsh conditions. Here, we determine effects of environmental factors on wild sable gut microbial communities between high and low altitude habitats using Illumina Miseq sequencing of bacterial 16S rRNA genes. Our results showed that despite wild sable gut microbial community diversity being resilient to many environmental factors, community composition was sensitive to altitude. Wild sable gut microbial communities were dominated by Firmicutes (relative abundance 38.23%), followed by Actinobacteria (30.29%), and Proteobacteria (28.15%). Altitude was negatively correlated with the abundance of Firmicutes, suggesting sable likely consume more vegetarian food in lower habitats where plant diversity, temperature and vegetation coverage were greater. In addition, our functional genes prediction and qPCR results demonstrated that energy/fat processing microorganisms and functional genes are enriched with increasing altitude, which likely enhanced metabolic functions and supported wild sables to survive in elevated habitats. Overall, our results improve the knowledge of the ecological impact of habitat change, providing insights into wild animal protection at the mountain area with hash climate conditions.

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