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1.
Photochem Photobiol Sci ; 20(3): 379-389, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33721276

RESUMO

Bryophytes, including Sphagnum, are common species in alpine and boreal regions especially on mires, where full sunlight exposes the plants to the damaging effects of UV radiation. Sphagnum species containing UV-protecting compounds might offer a biomass source for nature-based sunscreens to replace the synthetic ones. In this study, potential compounds and those linked in cell wall structures were obtained by using methanol and alkali extractions and the UV absorption of these extracts from three common Sphagnum moss species Sphagnum magellanicum, Sphagnum fuscum and Sphagnum fallax collected in spring and autumn from western Finland are described. Absorption spectrum screening (200-900 nm) and luminescent biosensor (Escherichia coli DPD2794) methodology were used to examine and compare the protection against UV radiation. Additionally, the antioxidant potential was evaluated using hydrogen peroxide scavenging (SCAV), oxygen radical absorbance capacity (ORAC) and ferric reducing absorbance capacity (FRAP). Total phenolic content was also determined using the Folin-Ciocalteu method. The results showed that methanol extractable compounds gave higher UV absorption with the used methods. Sphagnum fallax appeared to give the highest absorption in UV-B and UV-A wavelengths. In all assays except the SCAV test, the methanol extracts of Sphagnum samples collected in autumn indicated the highest antioxidant capacity and polyphenol content. Sphagnum fuscum implied the highest antioxidant capacity and phenolic content. There was low antioxidant and UV absorption provided by the alkali extracts of these three species.


Assuntos
Extratos Vegetais/química , Sphagnopsida/química , Raios Ultravioleta , Antioxidantes/química , Técnicas Biossensoriais , Dano ao DNA/efeitos da radiação , Cromatografia Gasosa-Espectrometria de Massas , Fenóis/química , Extratos Vegetais/análise , Polifenóis/análise , Polifenóis/química , Estações do Ano , Espectrofotometria , Sphagnopsida/metabolismo
2.
Sci Rep ; 10(1): 8592, 2020 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-32451474

RESUMO

Peatlands are one of the most important ecosystems due to their biodiversity and abundant organic compounds; therefore, it is important to observe how different plant species in peatlands react to changing environmental conditions. Sphagnum spp. are the main component of peatlands and are considered as the creator of conditions favorable for carbon storage in the form of peat. Sphagnum angustifolium and Sphagnum fallax are taxonomically very close species. To examine their adaptability to climate change, we studied the morphology and pigment content of these two species from environmental manipulation sites in Poland, where the environment was continuously manipulated for temperature and precipitation. The warming of peat was induced by using infrared heaters, whereas total precipitation was reduced by a curtain that cuts the nighttime precipitation. Morphology of S. angustifolium stayed under climate manipulation relatively stable. However, the main morphological parameters of S. fallax were significantly affected by precipitation reduction. Thus, this study indicates S. angustifolium is better adapted in comparison to S. fallax for drier and warmer conditions.


Assuntos
Clorofila/metabolismo , Sphagnopsida/fisiologia , Biodiversidade , Carbono/metabolismo , Mudança Climática , Ecossistema , Chuva , Sphagnopsida/metabolismo , Temperatura
3.
PLoS One ; 15(2): e0228383, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32017783

RESUMO

Biological nitrogen (N) fixation is an important process supporting primary production in ecosystems, especially in those where N availability is limiting growth, such as peatlands and boreal forests. In many peatlands, peat mosses (genus Sphagnum) are the prime ecosystem engineers, and like feather mosses in boreal forests, they are associated with a diverse community of diazotrophs (N2-fixing microorganisms) that live in and on their tissue. The large variation in N2 fixation rates reported in literature remains, however, to be explained. To assess the potential roles of habitat (including nutrient concentration) and species traits (in particular litter decomposability and photosynthetic capacity) on the variability in N2 fixation rates, we compared rates associated with various Sphagnum moss species in a bog, the surrounding forest and a fen in Sweden. We found appreciable variation in N2 fixation rates among moss species and habitats, and showed that both species and habitat conditions strongly influenced N2 fixation. We here show that higher decomposition rates, as explained by lower levels of decomposition-inhibiting compounds, and higher phosphorous (P) levels, are related with higher diazotrophic activity. Combining our findings with those of other studies, we propose a conceptual model in which both species-specific traits of mosses (as related to the trade-off between rapid photosynthesis and resistance to decomposition) and P availability, explain N2 fixation rates. This is expected to result in a tight coupling between P and N cycling in peatlands.


Assuntos
Nitrogênio/análise , Fósforo/análise , Sphagnopsida/crescimento & desenvolvimento , Ecossistema , Florestas , Modelos Teóricos , Fixação de Nitrogênio , Fotossíntese , Sphagnopsida/classificação , Sphagnopsida/metabolismo , Suécia , Simbiose
4.
Environ Pollut ; 257: 113625, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31806460

RESUMO

Natural media such as soil and sediment contain mineralogical and organic components with distinct chemical, surface, and electrostatic properties. To better understand the role of various soil and sediment components on particle transport, columns were packed with quartz sand and natural sediment with added Fe oxyhydroxide coating, illite clay, and peat moss to investigate how these added components influence nTiO2 retention and transport in geochemically heterogeneous medium. Results showed that nTiO2 transport was low at pH 5, attributable to the electrostatic attraction between positively-charged nTiO2 and negatively-charged medium. While illite did not notably affect nTiO2 transport at pH 5, Fe oxyhydroxide coating increased nTiO2 transport due to electrostatic repulsion between Fe oxyhydroxide and nTiO2. Peat moss also increased nTiO2 transport at pH 5, attributable to the increased DOC concentration, which resulted in higher DOC adsorption to nTiO2 and intensified electrostatic repulsion between nTiO2 and the medium. At pH 9, nTiO2 transport was high due to the electrostatic repulsion between negatively-charged nTiO2 and medium surfaces. Fe oxyhydroxide coating at pH 9 slightly delayed nTiO2 transport due to electrostatic attraction, while illite clay and peat moss substantially inhibited nTiO2 transport via straining/entrapment or electrostatic attraction. Overall, this study demonstrated that pH has a considerable effect on how minerals and organic components of a medium influence nTiO2 transport. At low pH, electrostatic attraction was the dominant mechanism, therefore, nTiO2 mobility was low regardless of the differences in mineralogical and organic components. Conversely, nTiO2 mobility was high at high pH and nTiO2 retention was dominated by straining/entrapment and sensitive to the mineralogical and organic composition of the medium.


Assuntos
Argila , Compostos Férricos , Minerais , Nanopartículas , Sphagnopsida , Titânio , Adsorção , Argila/química , Compostos Férricos/química , Sedimentos Geológicos/química , Minerais/química , Solo/química , Sphagnopsida/metabolismo , Titânio/química , Titânio/metabolismo
5.
Sci Total Environ ; 688: 684-690, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31254834

RESUMO

The isolation of highly efficient methanotrophic communities is crucial for the optimization of methane bioconversion into products with a high market value such as polyhydroxyalkanoates (PHA). The research here presented aimed at enriching a methanotrophic consortium from two different inocula (Sphagnum peat moss (Sp) and Sphagnum and activated sludge (M)) able to accumulate PHA while efficiently oxidizing CH4. Moreover, the effect of the temperature and phosphorus limitation on the biodegradation rate of CH4 and the PHA accumulation potential was investigated. Higher CH4 degradation rates were obtained under P availability at increasing temperature (25, 30 and 37 °C). The biomass enriched from the mixed inoculum always exhibited a superior biodegradation performance regardless of the temperature (a maximum value of 84.3 ±â€¯8.4 mg CH4 h-1 g biomass-1 was recorded at 37 °C). The results of the PHB production showed that phosphorus limitation is required to promote PHB accumulation, the highest PHB content being observed with the Sphagnum inoculum at 25 °C (13.6 ±â€¯5.6%). The differential specialization of the microbial communities depending on the enrichment temperature supported the key role of this parameter on the results obtained. In all cases after the completion of the enrichment process and of the P limitation tests, Methylocystis, a type II methanotroph known for its ability to accumulate PHA, was the genus that became dominant (reaching percentages from 16 to 46% depending on the enrichment temperature). Thus, the results here obtained demonstrated for the first time the relevance of the temperature used for the enrichment of the methanotrophic bacteria to boost PHA production yields under P limiting condition, highlighting the importance of optimizing culture conditions to improve the cost-efficiency of bioprocesses based on using methane as the primary feedstock for the PHA industrial market.


Assuntos
Biodegradação Ambiental , Metano/metabolismo , Poli-Hidroxialcanoatos/metabolismo , Sphagnopsida/metabolismo , Fósforo , Temperatura
6.
Sci Total Environ ; 650(Pt 1): 1652-1663, 2019 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-30017103

RESUMO

Trace elements in native cranberry (Vaccinium oxycoccus) were compared with the underlying Sphagnum moss on which it grows, from two remote ombrotrophic (rain-fed) peat bogs in northern Alberta, Canada. The purpose of the comparison was to distinguish between dust inputs to the berries versus plant uptake from the substrate, and to determine the natural abundance of trace elements in native berries. Using Al as an indicator of the abundance of soil-derived mineral particles, the abundance of dust on the surface of the berries is 20 to 29× lower than that of the substrate (moss). Other lithophile elements (V, Cr, Co, Ga, Li and Y) show similar differences between moss and berry. The concentrations of Rb and Ba in berries were similar to moss and Sr within a factor of 3 to 4×, probably reflecting passive uptake of these lithophile elements by the plants, even though they have no known physiological function. Of the micronutrients examined (Mn, Fe, Ni, Cu, Zn and Mo), Cu and Mn were more abundant in berries than moss, Ni and Zn yielded similar concentrations in both whereas Fe followed by Mo showed the greatest concentration difference. For these micronutrients, uptake by the plants through their roots via the substrate (moss and peat) outweighs contributions from atmospheric dusts. In respect to potentially toxic "heavy metals", Pb concentrations in the moss (BMW, 89 ±â€¯7.3 µg/kg; CMW, 93 ±â€¯27 µg/kg) are below the natural, "background" values reported for ancient layers of Swiss peat from the mid-Holocene (>6000 years old). The Pb concentrations in the berries, however, are 19 to 47× lower than in the underlying moss indicating that Pb in the berries, like Al, is exclusively supplied by dust. Cadmium in the berries is at or above the level found in moss due to active uptake by the plants from the substrate, most likely because of the chemical similarity of this element to Zn. Silver, Sb and Tl in the berries were

Assuntos
Poluentes Atmosféricos/análise , Poluentes Atmosféricos/metabolismo , Monitoramento Ambiental , Oligoelementos/análise , Oligoelementos/metabolismo , Vaccinium/química , Vaccinium/metabolismo , Alberta , Poeira/análise , Solo/química , Sphagnopsida/química , Sphagnopsida/metabolismo , Áreas Alagadas
7.
Glob Chang Biol ; 25(1): 108-120, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30346105

RESUMO

Peat mosses (Sphagnum) hold exceptional importance in the control of global carbon fluxes and climate because of the vast stores of carbon bound up in partially decomposed biomass (peat). This study tests the hypothesis that the early diversification of Sphagnum was in the Northern Hemisphere, with subsequent range expansions to tropical latitudes and the Southern Hemisphere. A phylogenetic analysis of 192 accessions representing the moss class Sphagnopsida based on four plastid loci was conducted in conjunction with biogeographic analyses using BioGeoBEARS to investigate the tempo and mode of geographic range evolution. Analyses support the hypothesis that the major intrageneric clades of peat-forming species accounting for >90% of peat moss diversity originated and diversified at northern latitudes. The genus underwent multiple range expansions into tropical and Southern Hemisphere regions. Range evolution in peat mosses was most common within latitudinal zones, attesting to the relative difficulty of successfully invading new climate zones. Allopolyploidy in Sphagnum (inferred from microsatellite heterozygosity) does not appear to be biased with regard to geographic region nor intrageneric clade. The inference that Sphagnum diversified in cool-or cold-climate regions and repeatedly expanded its range into tropical regions makes the genus an excellent model for studying morphological, physiological, and genomic traits associated with adaptation to warming climates.


Assuntos
Adaptação Fisiológica/fisiologia , Clima , Sphagnopsida/fisiologia , Biodiversidade , Evolução Biológica , Carbono/metabolismo , Mudança Climática , Filogenia , Sphagnopsida/classificação , Sphagnopsida/genética , Sphagnopsida/metabolismo
8.
J Chem Ecol ; 44(12): 1146-1157, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30294748

RESUMO

Sphagnum mosses mediate long-term carbon accumulation in peatlands. Given their functional role as keystone species, it is important to consider their responses to ecological gradients and environmental changes through the production of phenolics. We compared the extent to which Sphagnum phenolic production was dependent on species, microhabitats and season, and how surrounding dwarf shrubs responded to Sphagnum phenolics. We evaluated the phenolic profiles of aqueous extracts of Sphagnum fallax and Sphagnum magellanicum over a 6-month period in two microhabitats (wet lawns versus dry hummocks) in a French peatland. Phenolic profiles of water-soluble extracts were measured by UHPLC-QTOF-MS. Andromeda polifolia mycorrhizal colonization was quantified by assessing the intensity of global root cortex colonization. Phenolic profiles of both Sphagnum mosses were species-, season- and microhabitat- dependant. Sphagnum-derived acids were the phenolics mostly recovered; relative quantities were 2.5-fold higher in S. fallax than in S. magellanicum. Microtopography and vascular plant cover strongly influenced phenolic profiles, especially for minor metabolites present in low abundance. Higher mycorrhizal colonization of A. polifolia was found in lawns as compared to hummocks. Mycorrhizal abundance, in contrast to environmental parameters, was correlated with production of minor phenolics in S. fallax. Our results highlight the close interaction between mycorrhizae such as those colonizing A. polifolia and the release of Sphagnum phenolic metabolites and suggest that Sphagnum-derived acids and minor phenolics play different roles in this interaction. This work provides new insight into the ecological role of Sphagnum phenolics by proposing a strong association with mycorrhizal colonization of shrubs.


Assuntos
Ericaceae/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Sphagnopsida/química , Cromatografia Líquida de Alta Pressão , Ecossistema , Ericaceae/microbiologia , Fenóis/análise , Fenóis/química , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Análise de Componente Principal , Estações do Ano , Solo/química , Espectrometria de Massas por Ionização por Electrospray , Sphagnopsida/metabolismo , Água/química
9.
Appl Environ Microbiol ; 84(23)2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-30217851

RESUMO

Sphagnum-dominated peatlands play an important role in global carbon storage and represent significant sources of economic and ecological value. While recent efforts to describe microbial diversity and metabolic potential of the Sphagnum microbiome have demonstrated the importance of its microbial community, little is known about the viral constituents. We used metatranscriptomics to describe the diversity and activity of viruses infecting microbes within the Sphagnum peat bog. The vegetative portions of six Sphagnum plants were obtained from a peatland in northern Minnesota, and the total RNA was extracted and sequenced. Metatranscriptomes were assembled and contigs were screened for the presence of conserved virus marker genes. Using bacteriophage capsid protein gp23 as a marker for phage diversity, we identified 33 contigs representing undocumented phages that were active in the community at the time of sampling. Similarly, RNA-dependent RNA polymerase and the nucleocytoplasmic large DNA virus (NCLDV) major capsid protein were used as markers for single-stranded RNA (ssRNA) viruses and NCLDV, respectively. In total, 114 contigs were identified as originating from undescribed ssRNA viruses, 22 of which represent nearly complete genomes. An additional 64 contigs were identified as being from NCLDVs. Finally, 7 contigs were identified as putative virophage or polinton-like viruses. We developed co-occurrence networks with these markers in relation to the expression of potential-host housekeeping gene rpb1 to predict virus-host relationships, identifying 13 groups. Together, our approach offers new tools for the identification of virus diversity and interactions in understudied clades and suggests that viruses may play a considerable role in the ecology of the Sphagnum microbiome.IMPORTANCE Sphagnum-dominated peatlands play an important role in maintaining atmospheric carbon dioxide levels by modifying conditions in the surrounding soil to favor the growth of Sphagnum over that of other plant species. This lowers the rate of decomposition and facilitates the accumulation of fixed carbon in the form of partially decomposed biomass. The unique environment produced by Sphagnum enriches for the growth of a diverse microbial consortia that benefit from and support the moss's growth, while also maintaining the hostile soil conditions. While a growing body of research has begun to characterize the microbial groups that colonize Sphagnum, little is currently known about the ecological factors that constrain community structure and define ecosystem function. Top-down population control by viruses is almost completely undescribed. This study provides insight into the significant viral influence on the Sphagnum microbiome and identifies new potential model systems to study virus-host interactions in the peatland ecosystem.


Assuntos
Bacteriófagos/isolamento & purificação , Microbiota , Sphagnopsida/virologia , Vírus/isolamento & purificação , Bacteriófagos/classificação , Bacteriófagos/genética , Bacteriófagos/metabolismo , Biodiversidade , Biomassa , Proteínas do Capsídeo/genética , Dióxido de Carbono/metabolismo , Filogenia , Sphagnopsida/crescimento & desenvolvimento , Sphagnopsida/metabolismo , Vírus/classificação , Vírus/genética , Vírus/metabolismo
10.
Environ Pollut ; 237: 468-472, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29510366

RESUMO

Little information exists concerning the long-term interactive effect of nitrogen (N) addition with phosphorus (P) and potassium (K) on Sphagnum N status. This study was conducted as part of a long-term N manipulation on Whim bog in south Scotland to evaluate the long-term alleviation effects of phosphorus (P) and potassium (K) on N saturation of Sphagnum (S. capillifolium). On this ombrotrophic peatland, where ambient deposition was 8 kg N ha-1 yr-1, 56 kg N ha-1 yr-1 of either ammonium (NH4+, Nred) or nitrate (NO3-, Nox) with and without P and K, were added over 11 years. Nutrient concentrations of Sphagnum stem and capitulum, and pore water quality of the Sphagnum layer were assessed. The N-saturated Sphagnum caused by long-term (11 years) and high doses (56 kg N ha-1 yr-1) of reduced N was not completely ameliorated by P and K addition; N concentrations in Sphagnum capitula for Nred 56 PK were comparable with those for Nred 56, although N concentrations in Sphagnum stems for Nred 56 PK were lower than those for Nred 56. While dissolved inorganic nitrogen (DIN) concentrations in pore water for Nred 56 PK were not different from Nred 56, they were lower for Nox 56 PK than for Nox 56 whose stage of N saturation had not advanced compared to Nred 56. These results indicate that increasing P and K availability has only a limited amelioration effect on the N assimilation of Sphagnum at an advanced stage of N saturation. This study concluded that over the long-term P and K additions will not offset the N saturation of Sphagnum.


Assuntos
Nitrogênio/análise , Fósforo/análise , Potássio/metabolismo , Sphagnopsida/química , Compostos de Amônio , Monitoramento Ambiental , Nitratos , Nitrogênio/metabolismo , Fósforo/metabolismo , Caules de Planta , Escócia , Sphagnopsida/metabolismo
11.
Anal Chem ; 90(1): 702-707, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29210566

RESUMO

One critical aspect of mass spectrometry imaging (MSI) is the need to confidently identify detected analytes. While orthogonal tandem MS (e.g., LC-MS2) experiments from sample extracts can assist in annotating ions, the spatial information about these molecules is lost. Accordingly, this could cause mislead conclusions, especially in cases where isobaric species exhibit different distributions within a sample. In this Technical Note, we employed a multimodal imaging approach, using matrix assisted laser desorption/ionization (MALDI)-MSI and liquid extraction surface analysis (LESA)-MS2I, to confidently annotate and localize a broad range of metabolites involved in a tripartite symbiosis system of moss, cyanobacteria, and fungus. We found that the combination of these two imaging modalities generated very congruent ion images, providing the link between highly accurate structural information onfered by LESA and high spatial resolution attainable by MALDI. These results demonstrate how this combined methodology could be very useful in differentiating metabolite routes in complex systems.


Assuntos
Produtos Biológicos/análise , Imagem Multimodal/métodos , Extração em Fase Sólida/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Ascomicetos/metabolismo , Nostoc muscorum/metabolismo , Sphagnopsida/metabolismo
12.
Appl Environ Microbiol ; 84(3)2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29180368

RESUMO

Ombrotrophic peatlands are a recognized global carbon reservoir. Without restoration and peat regrowth, harvested peatlands are dramatically altered, impairing their carbon sink function, with consequences for methane turnover. Previous studies determined the impact of commercial mining on the physicochemical properties of peat and the effects on methane turnover. However, the response of the underlying microbial communities catalyzing methane production and oxidation have so far received little attention. We hypothesize that with the return of Sphagnum spp. postharvest, methane turnover potential and the corresponding microbial communities will converge in a natural and restored peatland. To address our hypothesis, we determined the potential methane production and oxidation rates in natural (as a reference), actively mined, abandoned, and restored peatlands over two consecutive years. In all sites, the methanogenic and methanotrophic population sizes were enumerated using quantitative PCR (qPCR) assays targeting the mcrA and pmoA genes, respectively. Shifts in the community composition were determined using Illumina MiSeq sequencing of the mcrA gene and a pmoA-based terminal restriction fragment length polymorphism (t-RFLP) analysis, complemented by cloning and sequence analysis of the mmoX gene. Peat mining adversely affected methane turnover potential, but the rates recovered in the restored site. The recovery in potential activity was reflected in the methanogenic and methanotrophic abundances. However, the microbial community composition was altered, being more pronounced for the methanotrophs. Overall, we observed a lag between the recovery of the methanogenic/methanotrophic activity and the return of the corresponding microbial communities, suggesting that a longer duration (>15 years) is needed to reverse mining-induced effects on the methane-cycling microbial communities.IMPORTANCE Ombrotrophic peatlands are a crucial carbon sink, but this environment is also a source of methane, an important greenhouse gas. Methane emission in peatlands is regulated by methane production and oxidation catalyzed by methanogens and methanotrophs, respectively. Methane-cycling microbial communities have been documented in natural peatlands. However, less is known of their response to peat mining and of the recovery of the community after restoration. Mining exerts an adverse impact on potential methane production and oxidation rates and on methanogenic and methanotrophic population abundances. Peat mining also induced a shift in the methane-cycling microbial community composition. Nevertheless, with the return of Sphagnum spp. in the restored site after 15 years, methanogenic and methanotrophic activity and population abundance recovered well. The recovery, however, was not fully reflected in the community composition, suggesting that >15 years are needed to reverse mining-induced effects.


Assuntos
Metano/metabolismo , Microbiota/fisiologia , Mineração , Microbiologia do Solo , Solo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carbono/metabolismo , Ecossistema , Euryarchaeota/genética , Euryarchaeota/metabolismo , Microbiota/genética , Fixação de Nitrogênio , Oxirredução , Oxigenases , Filogenia , Sphagnopsida/metabolismo , Áreas Alagadas
13.
Chemosphere ; 181: 208-215, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28441611

RESUMO

In the present work, the genotoxic effect of cadmium and lead supplied in a laboratory trial, was investigated for the first time in the moss Sphagnum palustre, by ISSR molecular markers. A total of 169 reproducible bands were obtained with 12 primers, ten of which gave polymorphisms (i.e., appearance/disappearance of bands), indicating a clear genotoxic effect induced by the metals. Both metals induced a decrease of the genome template stability in a dose dependent manner. At concentration >10-5 Cd also induced a general toxic effect in S. palustre, leading to chlorophyll degradation and moss death. Moreover, we followed the fate of supplied heavy metals into the moss tissue by SEM-EDX to see if they entered the cells. SEM-EDX observations on moss cultures treated with equimolar concentrations of the two metals showed that most Pb precipitated in form of particles on moss surface, while Cd did not aggregate in particles and was not found on moss surface. In light of these findings, we concluded that probably Pb induced a genotoxic effect at lower intracellular concentrations than Cd.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Sphagnopsida/metabolismo , Briófitas/genética , Briófitas/metabolismo , Cádmio/metabolismo , Precipitação Química , Instabilidade Genômica , Metais Pesados/toxicidade , Mutagênicos , Polimorfismo Genético , Sphagnopsida/genética
15.
Sci Rep ; 5: 16931, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26603894

RESUMO

Mixotrophic protists are increasingly recognized for their significant contribution to carbon (C) cycling. As phototrophs they contribute to photosynthetic C fixation, whilst as predators of decomposers, they indirectly influence organic matter decomposition. Despite these direct and indirect effects on the C cycle, little is known about the responses of peatland mixotrophs to climate change and the potential consequences for the peatland C cycle. With a combination of field and microcosm experiments, we show that mixotrophs in the Sphagnum bryosphere play an important role in modulating peatland C cycle responses to experimental warming. We found that five years of consecutive summer warming with peaks of +2 to +8°C led to a 50% reduction in the biomass of the dominant mixotrophs, the mixotrophic testate amoebae (MTA). The biomass of other microbial groups (including decomposers) did not change, suggesting MTA to be particularly sensitive to temperature. In a microcosm experiment under controlled conditions, we then manipulated the abundance of MTA, and showed that the reported 50% reduction of MTA biomass in the field was linked to a significant reduction of net C uptake (-13%) of the entire Sphagnum bryosphere. Our findings suggest that reduced abundance of MTA with climate warming could lead to reduced peatland C fixation.


Assuntos
Carbono/metabolismo , Mudança Climática , Bactérias/metabolismo , Biomassa , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Ecossistema , Metabolismo Energético , Fungos/metabolismo , Sphagnopsida/metabolismo
16.
J Environ Radioact ; 143: 110-122, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25752706

RESUMO

Batch sorption experiments were conducted to evaluate the sorption behaviour of iodide and the microbial impact on iodide sorption in the surface moss, subsurface peat, gyttja, and clay layers of a nutrient-poor boreal bog. The batch distribution coefficient (Kd) values of iodide decreased as a function of sampling depth. The highest Kd values, 4800 L/Kg dry weight (DW) (geometric mean), were observed in the fresh surface moss and the lowest in the bottom clay (geometric mean 90 mL/g DW). In the surface moss, peat and gyttja layers, which have a high organic matter content (on average 97%), maximum sorption was observed at a pH between ∼ 4 and 5 and in the clay layer at pH 2. The Kd values were significantly lower in sterilized samples, being 20-fold lower than the values found for the unsterilized samples. In addition, the recolonization of sterilized samples with a microbial population from the fresh samples restored the sorption capacity of surface moss, peat and gyttja samples, indicating that the decrease in the sorption was due to the destruction of microbes and supporting the hypothesis that microbes are necessary for the incorporation of iodide into the organic matter. Anoxic conditions reduced the sorption of iodide in fresh, untreated samples, similarly to the effect of sterilization, which supports the hypothesis that iodide is oxidized into I2/HIO before incorporation into the organic matter. Furthermore, the Kd values positively correlated with peroxidase activity in surface moss, subsurface peat and gyttja layers at +20 °C, and with the bacterial cell counts obtained from plate count agar at +4 °C. Our results demonstrate the importance of viable microbes for the sorption of iodide in the bog environment, having a high organic matter content and a low pH.


Assuntos
Iodetos/metabolismo , Radioisótopos do Iodo/metabolismo , Microbiologia do Solo , Poluentes Radioativos do Solo/metabolismo , Áreas Alagadas , Adsorção , Silicatos de Alumínio/análise , Argila , Finlândia , Sedimentos Geológicos/análise , Sedimentos Geológicos/microbiologia , Concentração de Íons de Hidrogênio , Solo/química , Sphagnopsida/metabolismo , Água/química
17.
Glob Chang Biol ; 21(6): 2309-20, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25580711

RESUMO

Boreal peatlands store large amounts of carbon, reflecting their important role in the global carbon cycle. The short-term exchange and the long-term storage of atmospheric carbon dioxide (CO2 ) in these ecosystems are closely associated with the permanently wet surface conditions and are susceptible to drought. Especially, the single most important peat forming plant genus, Sphagnum, depends heavily on surface wetness for its primary production. Changes in rainfall patterns are expected to affect surface wetness, but how this transient rewetting affects net ecosystem exchange of CO2 (NEE) remains unknown. This study explores how the timing and characteristics of rain events during photosynthetic active periods, that is daytime, affect peatland NEE and whether rain event associated changes in environmental conditions modify this response (e.g. water table, radiation, vapour pressure deficit, temperature). We analysed an 11-year time series of half-hourly eddy covariance and meteorological measurements from Degerö Stormyr, a boreal peatland in northern Sweden. Our results show that daytime rain events systematically decreased the sink strength of peatlands for atmospheric CO2 . The decrease was best explained by rain associated reduction in light, rather than by rain characteristics or drought length. An average daytime growing season rain event reduced net ecosystem CO2 uptake by 0.23-0.54 gC m(-2) . On an annual basis, this reduction of net CO2 uptake corresponds to 24% of the annual net CO2 uptake (NEE) of the study site, equivalent to a 4.4% reduction of gross primary production (GPP) during the growing season. We conclude that reduced light availability associated with rain events is more important in explaining the NEE response to rain events than rain characteristics and changes in water availability. This suggests that peatland CO2 uptake is highly sensitive to changes in cloud cover formation and to altered rainfall regimes, a process hitherto largely ignored.


Assuntos
Dióxido de Carbono/metabolismo , Chuva , Sphagnopsida/metabolismo , Luz Solar , Ciclo do Carbono , Ecossistema , Fotossíntese , Solo , Suécia
18.
Glob Chang Biol ; 21(6): 2357-65, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25545459

RESUMO

Nitrogen (N) nutrition in pristine peatlands relies on the natural input of inorganic N through atmospheric deposition or biological dinitrogen (N2 ) fixation. However, N2 fixation and its significance for N cycling, plant productivity, and peat buildup are mostly associated with the presence of Sphagnum mosses. Here, we report high nonsymbiotic N2 -fixation rates in two pristine Patagonian bogs with diversified vegetation and natural N deposition. Nonsymbiotic N2 fixation was measured in samples from 0 to 10, 10 to 20, and 40 to 50 cm depth using the (15) N2 assay as well as the acetylene reduction assay (ARA). The ARA considerably underestimated N2 fixation and can thus not be recommended for peatland studies. Based on the (15) N2 assay, high nonsymbiotic N2 -fixation rates of 0.3-1.4 µmol N2  g(-1)  day(-1) were found down to 50 cm under micro-oxic conditions (2 vol.%) in samples from plots covered by Sphagnum magellanicum or by vascular cushion plants, latter characterized by dense and deep aerenchyma roots. Peat N concentrations point to greater potential of nonsymbiotic N2 fixation under cushion plants, likely because of the availability of easily decomposable organic compounds and oxic conditions in the rhizosphere. In the Sphagnum plots, high N2 fixation below 10 cm depth rather reflects the potential during dry periods or low water level when oxygen penetrates the top peat layer and triggers peat mineralization. Natural abundance of the (15) N isotope of live Sphagnum (5.6 δ‰) from 0 to 10 cm points to solely N uptake from atmospheric deposition and nonsymbiotic N2 fixation. A mean (15) N signature of -0.7 δ‰ of peat from the cushion plant plots indicates additional N supply from N mineralization. Our findings suggest that nonsymbiotic N2 fixation overcomes N deficiency in different vegetation communities and has great significance for N cycling and peat accumulation in pristine peatlands.


Assuntos
Embriófitas/metabolismo , Ciclo do Nitrogênio , Fixação de Nitrogênio , Solo/química , Chile , Nitrogênio/análise , Isótopos de Nitrogênio , Raízes de Plantas/metabolismo , Sphagnopsida/metabolismo , Áreas Alagadas
19.
New Phytol ; 203(1): 70-80, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24689361

RESUMO

Northern peatlands represent a large global carbon store that can potentially be destabilized by summer water table drawdown. Precipitation can moderate the negative impacts of water table drawdown by rewetting peatmoss (Sphagnum spp.), the ecosystem's key species. Yet, the frequency of such rewetting required for it to be effective remains unknown. We experimentally assessed the importance of precipitation frequency for Sphagnum water supply and carbon uptake during a stepwise decrease in water tables in a growth chamber. CO2 exchange and the water balance were measured for intact cores of three peatmoss species (Sphagnum majus, Sphagnum balticum and Sphagnum fuscum) representative of three hydrologically distinct peatland microhabitats (hollow, lawn and hummock) and expected to differ in their water table-precipitation relationships. Precipitation contributed significantly to peatmoss water supply when the water table was deep, demonstrating the importance of precipitation during drought. The ability to exploit transient resources was species-specific; S. fuscum carbon uptake increased linearly with precipitation frequency for deep water tables, whereas carbon uptake by S. balticum and S. majus was depressed at intermediate precipitation frequencies. Our results highlight an important role for precipitation in carbon uptake by peatmosses. Yet, the potential to moderate the impact of drought is species-specific and dependent on the temporal distribution of precipitation.


Assuntos
Ciclo do Carbono , Secas , Sphagnopsida/metabolismo , Água/fisiologia , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Ecossistema , Água Subterrânea , Fotossíntese , Chuva , Estações do Ano , Sphagnopsida/crescimento & desenvolvimento
20.
Proc Natl Acad Sci U S A ; 111(2): 734-9, 2014 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-24379382

RESUMO

Nitrogen (N) accumulation rates in peatland ecosystems indicate significant biological atmospheric N2 fixation associated with Sphagnum mosses. Here, we show that the linkage between methanotrophic carbon cycling and N2 fixation may constitute an important mechanism in the rapid accumulation of N during the primary succession of peatlands. In our experimental stable isotope enrichment study, previously overlooked methane-induced N2 fixation explained more than one-third of the new N input in the younger peatland stages, where the highest N2 fixation rates and highest methane oxidation activities co-occurred in the water-submerged moss vegetation.


Assuntos
Alphaproteobacteria/metabolismo , Ciclo do Carbono/fisiologia , Metano/metabolismo , Ciclo do Nitrogênio/fisiologia , Microbiologia do Solo , Sphagnopsida/crescimento & desenvolvimento , Sphagnopsida/microbiologia , Análise de Variância , Isótopos de Carbono/metabolismo , Finlândia , Isótopos de Nitrogênio/metabolismo , Sphagnopsida/metabolismo
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