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Land use is a key factor driving changes in soil carbon (C) cycle and contents worldwide. The priming effect (PE)-CO2 emissions from changed soil organic matter decomposition in response to fresh C inputs-is one of the most unpredictable phenomena associated with C cycling and related nutrient mobilization. Yet, we know very little about the influence of land use on soil PE across contrasting environments. Here, we conducted a continental-scale study to (i) determine the PE induced by 13 C-glucose additions to 126 cropland and seminatural (forests and grasslands) soils from 22 European countries; (ii) compare PE magnitude in soils under various crop types (i.e., cereals, nonpermanent industrial crops, and orchards); and (iii) model the environmental factors influencing PE. On average, PEs were negative in seminatural (with values ranging between -60 and 26 µg C g-1 soil after 35 days of incubation; median = -11) and cropland (from -55 to 27 µC g-1 soil; median = -4.3) soils, meaning that microbial communities preferentially switched from soil organic C decomposition to glucose mineralization. PE was significantly less negative in croplands compared with seminatural ecosystems and not influenced by the crop type. PE was driven by soil basal respiration (reflecting microbial activity), microbial biomass C, and soil organic C, which were all higher in seminatural ecosystems compared with croplands. This cross European experimental and modeling study elucidated that PE intensity is dependent on land use and allowed to clarify the factors regulating this important C cycling process.
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Microbiota , Solo , Biomassa , Carbono , Microbiologia do SoloRESUMO
Long-term contaminated environments have been recognized as potential hotspots for bacterial discovery in taxonomic and functional terms for bioremediation purposes. Here, bacterial diversity in waste sediment collected from a former industrial dumpsite and contaminated with petroleum hydrocarbon and heavy metals was investigated through the parallel application of culture-independent (16S rRNA gene amplicon sequencing) and -dependent (plate culturing followed by colony picking and identification of isolates by 16S rRNA gene Sanger sequencing) approaches. The bacterial diversities retrieved by both approaches greatly differed. Bacteroidetes and Proteobacteria were dominant in the culture-independent community, while Firmicutes and Actinobacteria were the main culturable groups. Only 2.7% of OTUs (operational taxonomic units) in the culture-independent dataset were cultured. Most of the culturable OTUs were absent or in very low abundances in the culture-independent dataset, revealing that culturing is a useful tool to study the rare bacterial biosphere. One culturable OTUs (comprising only the isolate SPR117) was identified as a potential new species in the genus Rhizorhapis (class Alphaproteobacteria) and was selected for further characterization. Phytopathogenicity tests showed that Rhizorhapis sp. strain SPR117 (ATCC TSD-228) is not pathogenic to lettuce, despite the only described species in this genus, Rhizorhapis suberifaciens, is causal agent of the lettuce corky root disease. The genome of the strain SPR117 was sequenced, assembled in 256 contigs, with a length of 4,419,522 bp and a GC content of 59.9%, and its further annotation revealed the presence of genes related to the resistance to arsenic, copper, iron, and mercury, among other metals. Therefore, the coupling of metataxonomics and culturing is a useful tool to obtain not only an improved description of bacterial communities in contaminated environments, but also to isolate microorganisms with bioremediation potential.
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Arsênio , Mercúrio , Metais Pesados , Petróleo , Cobre , Hidrocarbonetos , Ferro , RNA Ribossômico 16S/genéticaRESUMO
This study evaluates the feasibility of advanced biofilm microalgae cultivation in a twin layer (TL) system for nutrient removal (N and P) as the tertiary treatment in small wastewater treatment plants (WWTPs) located in sensitive areas. Furthermore, the potential valorisation of microalgae biomass as a component of bio-based fertilizers is assessed. Scenedesmus sp. was chosen among 33 microalgae strains for inoculation of TL due to its high growth rate and its nutrient uptake capacity. The tests carried out in the prototype were markedly efficient for total soluble and ammoniacal nitrogen removal (up to 66 and 94%, respectively). In terms of potential valorisation of microalgae, the nutrient content was 5.5% N (over 40% protein), 8.8% P2O5 and 1.5% K2O, high enzymatic activity, very low levels of heavy metals and no detectable pathogen presence. However, in the formulation of solid-state bio-based fertilizers, the microalgae proportions in blends of over 2% of microalgae led to negative effects on ryegrass (Lolium perenne L. ssp.) and barley (Hordeum vulgare ssp.). The obtained results demonstrate that TL represents a promising technology, which allows efficient tertiary treatment of urban wastewater and the production of high-quality bio-based fertilizer.
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Microalgas , Scenedesmus , Biomassa , Nutrientes , Águas ResiduáriasRESUMO
Large heterodyne receiver arrays (~100 pixel) allow astronomical instrumentations to map more area within limited space mission lifetime. One challenge is to generate multiple local oscillator (LO) beams. Here, we succeeded in generating 81 beams at 3.86 THz by combining a reflective, metallic Fourier grating with an unidirectional antenna coupled 3rd-order distributed feedback (DFB) quantum cascade laser (QCL). We have measured the diffracted 81 beams by scanning a single pyroelectric detector at a plane, which is in the far field for the diffraction beams. The measured output beam pattern agrees well with a simulated result from COMSOL Multiphysics, with respect to the angular distribution and power distribution among the 81 beams. We also derived the diffraction efficiency to be 94 ± 3%, which is very close to what was simulated for a manufactured Fourier grating (97%). For an array of equal superconducting hot electron bolometer mixers, 64 out of 81 beams can pump the HEB mixers with similar power, resulting in receiver sensitivities within 10%. Such a combination of a Fourier grating and a QCL can create an LO with 100 beams or more, enabling a new generation of large heterodyne arrays for astronomical instrumentation.
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BACKGROUND: Anticoagulation control in patients with atrial fibrillation (AF) has a multidisciplinary approach although is usually managed by general practitioners (GP) or haematologists. The aim of our study was to assess the quality of anticoagulation control with vitamin K antagonists (VKAs) in relation to the responsible specialist in a "real-world" AF population. METHODS: We consecutively enrolled VKA anticoagulated patients included in the FANTASIIA Registry from 2013 to 2015. We analysed demographical, clinical characteristics and the quality of anticoagulation control according to the specialist responsible (ie GPs or haematologists). RESULTS: Data on 1584 patients were included (42.5% females, mean age 74.0 ± 9.4 years): 977 (61.7%) patients were controlled by GPs and 607 (38.3%) by haematologists. Patients managed by GPs had higher previous heart disease (53.2% vs 43.3%, P < .001), heart failure (32.9% vs 26.5%, P < .008) and dilated cardiomyopathy (15.2% vs 8.7%, P < .001) with better renal function (69.3 ± 24.7 vs 63.1 ± 21.4 mL/min, P < .001) compared to patients managed by haematologists. There was no difference between groups in the type of AF, CHA2 DS2 -VASc or HAS-BLED scores, but patients with electrical cardioversion were more prevalent in GP group. The overall mean time in therapeutic range (TTR) assessed by Rosendaal method was 61.5 ± 24.9%; 52.6% of patients had TTR<65% and 60% of patients had TTR<70%. TTR was significantly lower in patients controlled by haematologists than by GPs (63 ± 24.4 vs 59.2 ± 25.6, P < .005). CONCLUSIONS: About 60% of AF patients anticoagulated with VKAs had poor anticoagulation control (ie TTR<70%), and their management was only slightly better than when it is managed by general practitioners.
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Anticoagulantes/uso terapêutico , Fibrilação Atrial/tratamento farmacológico , Qualidade da Assistência à Saúde/normas , Vitamina K/antagonistas & inibidores , Idoso , Cardiomiopatia Dilatada/complicações , Cardioversão Elétrica/estatística & dados numéricos , Feminino , Medicina Geral/normas , Medicina Geral/estatística & dados numéricos , Insuficiência Cardíaca/complicações , Hematologia/normas , Hematologia/estatística & dados numéricos , Humanos , Rim/fisiologia , Masculino , Estudos Prospectivos , Qualidade da Assistência à Saúde/estatística & dados numéricos , Sistema de Registros , Fatores de RiscoRESUMO
The study of microbial communities involved in soil bioremediation is important to identify the specific microbial characteristics that determine improved decontamination rates. Here, we characterized bacterial, archaeal, and fungal communities in terms of (i) abundance (using quantitative PCR) and (ii) taxonomic diversity and structure (using Illumina amplicon sequencing) during the bioremediation of long-term hydrocarbon-contaminated soil from an Alpine former military site during 15 weeks comparing biostimulation (inorganic NPK fertilization) vs. natural attenuation and considering the effect of temperature (10 vs. 20 °C). Although a considerable amount of total petroleum hydrocarbon (TPH) loss could be attributed to natural attenuation, significantly higher TPH removal rates were obtained with NPK fertilization and at increased temperature, which were related to the stimulation of the activities of indigenous soil microorganisms. Changing structures of bacterial and fungal communities significantly explained shifts in TPH contents in both natural attenuation and biostimulation treatments at 10 and 20 °C. However, archaeal communities, in general, and changing abundances and diversities in bacterial and fungal communities did not play a decisive role on the effectiveness of soil bioremediation. Gammaproteobacteria and Bacteroidia classes, within bacterial community, and undescribed/novel groups, within fungal community, proved to be actively involved in TPH removal in natural attenuation and biostimulation at both temperatures.
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Biodegradação Ambiental , Hidrocarbonetos/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Militares , Petróleo , Solo/químicaRESUMO
Microbial ecology has been recognized as useful in archaeological studies. At Archaic Monte Iato in Western Sicily, a native (indigenous) building was discovered. The objective of this study was the first examination of soil microbial communities related to this building. Soil samples were collected from archaeological layers at a ritual deposit (food waste disposal) in the main room and above the fireplace in the annex. Microbial soil characterization included abundance (cellular phospholipid fatty acids (PLFA), viable bacterial counts), activity (physiological profiles, enzyme activities of viable bacteria), diversity, and community structure (bacterial and fungal Illumina amplicon sequencing, identification of viable bacteria). PLFA-derived microbial abundance was lower in soils from the fireplace than in soils from the deposit; the opposite was observed with culturable bacteria. Microbial communities in soils from the fireplace had a higher ability to metabolize carboxylic and acetic acids, while those in soils from the deposit metabolized preferentially carbohydrates. The lower deposit layer was characterized by higher total microbial and bacterial abundance and bacterial richness and by a different carbohydrate metabolization profile compared to the upper deposit layer. Microbial community structures in the fireplace were similar and could be distinguished from those in the two deposit layers, which had different microbial communities. Our data confirmed our hypothesis that human consumption habits left traces on microbiota in the archaeological evidence; therefore, microbiological residues as part of the so-called ecofacts are, like artifacts, key indicators of consumer behavior in the past.
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Arqueologia , Atividades Humanas/história , Consórcios Microbianos/fisiologia , Microbiologia do Solo , Solo/química , Acetatos/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Carga Bacteriana , Biodiversidade , Biomassa , Ácidos Carboxílicos/metabolismo , Análise por Conglomerados , DNA Bacteriano , DNA Fúngico , Ensaios Enzimáticos , Ácidos Graxos/metabolismo , Fungos/classificação , Fungos/genética , Fungos/metabolismo , Processos Heterotróficos , História Antiga , Consórcios Microbianos/genética , Fosfolipídeos/metabolismo , RNA Ribossômico 16S/genéticaRESUMO
Shifts in soil microbial communities over altitudinal gradients and the driving factors are poorly studied. Their elucidation is indispensable to gain a comprehensive understanding of the response of ecosystems to global climate change. Here, we investigated soil archaeal, bacterial, and fungal communities at four Alpine forest sites representing a climosequence, over an altitudinal gradient from 545 to 2000 m above sea level (asl), regarding abundance and diversity by using qPCR and Illumina sequencing, respectively. Archaeal community was dominated by Thaumarchaeota, and no significant shifts were detected in abundance or community composition with altitude. The relative bacterial abundance increased at higher altitudes, which was related to increasing levels of soil organic matter and nutrients with altitude. Shifts in bacterial richness and diversity as well as community structure (comprised basically of Proteobacteria, Acidobacteria, Actinobacteria, and Bacteroidetes) significantly correlated with several environmental and soil chemical factors, especially soil pH. The site at the lowest altitude harbored the highest bacterial richness and diversity, although richness/diversity community properties did not show a monotonic decrease along the gradient. The relative size of fungal community also increased with altitude and its composition comprised Ascomycota, Basidiomycota, and Zygomycota. Changes in fungal richness/diversity and community structure were mainly governed by pH and C/N, respectively. The variation of the predominant bacterial and fungal classes over the altitudinal gradient was the result of the environmental and soil chemical factors prevailing at each site.
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Altitude , Biodiversidade , Microbiologia do Solo , Archaea/classificação , Archaea/isolamento & purificação , Bactérias/classificação , Bactérias/isolamento & purificação , Fenômenos Químicos , DNA Arqueal/genética , DNA Arqueal/isolamento & purificação , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , DNA Fúngico/genética , DNA Fúngico/isolamento & purificação , Fungos/classificação , Fungos/isolamento & purificação , Itália , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Análise de Sequência de DNA , Solo/química , TemperaturaRESUMO
Dry olive residue (DOR) is a waste product derived from olive oil extraction and has been proposed as an organic amendment. However, it has been demonstrated that a pre-treatment, such as its transformation by saprophytic fungi, is required before DOR soil application. A greenhouse experiment was designed where 0 and 50 g kg(-1) of raw DOR (DOR), Coriolopsis floccosa-transformed DOR (CORDOR) and Fusarium oxysporum-transformed DOR (FUSDOR) were added to soil. Analyses of the soil chemical properties as well as the structure and relative abundance of bacterial and actinobacterial communities were conducted after 0, 30 and 60 days following amendment. The different amendments produced a slight decrease in soil pH and significant increases in carbon fractions, C/N ratios, phenols and K, with these increases being more significant after DOR application. Quantitative PCR assays of the 16S rRNA gene and PLFA analyses showed that all amendments favoured bacterial growth at 30 and 60 days, although actinobacterial proliferation was more evident after CORDOR and FUSDOR application at 60 days. Bacterial and actinobacterial DGGE multivariate analyses showed that the amendments produced structural changes in both communities, especially after 60 days of amendment. PLFA data analysis identified changes in soil microbial communities according to the amendment considered, with FUSDOR and CORDOR being less disruptive than DOR. Finally, integrated analysis of all data monitored in the present study enabled us to conclude that the greatest impact on soil properties was caused by DOR at 30 days and that soil showed some degree of resilience after this time.
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Actinobacteria/crescimento & desenvolvimento , Olea/química , Microbiologia do Solo , Solo/química , Análise de Variância , Biodegradação Ambiental , Biotransformação , Carbono/análise , Cromatografia Gasosa , Coriolaceae/metabolismo , Eletroforese em Gel de Gradiente Desnaturante , Ácidos Graxos/análise , Fusarium/metabolismo , Concentração de Íons de Hidrogênio , Nitrogênio/análise , Olea/metabolismo , Fenóis/análise , Potássio/análise , RNA Ribossômico 16S/genética , Reação em Cadeia da Polimerase em Tempo Real , Espanha , Fatores de Tempo , Resíduos/análiseRESUMO
Sewage sludge is a polluting and hazardous waste generated in wastewater treatment plants with severe management problems. The high content in heavy metal, pathogens and micropolluting compounds limit the implementation of the available management methods. Anaerobic digestion could be an interesting treatment method, but must be improved since the biomethanisation of sewage sludge entails low biodegradability and low methane production. A sonication pre-treatment at lab scale is proposed to increase the organic matter solubilisation of sewage sludge and enhance the biomethanisation yield. Sonication time was optimised by analysing the physicochemical characteristics of sewage sludge (both total and soluble fraction) at different pre-treatment times. The pre-treatment time was fixed at 45 min under the study conditions given that the solubilisation of organic matter did not increase significantly at lower sonication times, whereas the concentration of total nitrogen increased markedly at higher times. The volatile fatty acids generation rate was also evaluated for the pre-treatment conditions. The anaerobic digestion of untreated and pre-treated sewage sludge was subsequently compared and promising results were obtained for loads of 1.0 g VS/L (VS, total volatile solids). The methane yield coefficient increased from 88 to 172 mLSTP/g VS (STP, 0 °C, 1 atm) after the pre-treatment, while biodegradability was found to be around 81% (in VS). Moreover, the allowed organic loading rate and methane production rate observed for the sewage sludge reached values of up to 4.1 kg VS/m(3)·d and 1270 LSTP/m(3)·d, respectively.
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Bactérias Anaeróbias/metabolismo , Reatores Biológicos , Metano/biossíntese , Esgotos/microbiologia , Sonicação/métodos , Biodegradação Ambiental , Carbono/análise , Ácidos Graxos Voláteis/metabolismo , Nitrogênio/análiseRESUMO
Dry olive residue (DOR) is an abundant waste product resulting from a two-phase olive oil extraction system. Due to its high organic and mineral content, this material has been proposed as an organic soil amendment; however, it presents phytotoxic and microtoxic properties. Thus, a pretreatment is necessary before its application to soil. Among the strategies for the bioremediation of DOR is treatment with ligninolytic fungi, e.g. Coriolopsis floccosa. This work aimed to assess the diversity of culturable fungi in a soil of the southeast Iberian Peninsula and to evaluate the short-term impact of untransformed and C. floccosa-transformed DOR on soil mycobiota. A total of 1,733 strains were isolated by the particle filtration method and were grouped among 109 different species using morphological and molecular methods. The majority of isolates were ascomycetes and were concentrated among three orders: Hypocreales, Eurotiales and Capnodiales. The soil amendment with untransformed DOR was associated with a depression in fungal diversity at 30 days and changes in the proportions of the major species. However, when C. floccosa-transformed DOR was applied to the soil, changes in fungal diversity were less evident, and species composition was similar to unamended soil.
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Fungos/patogenicidade , Olea/metabolismo , Microbiologia do Solo , Análise por Conglomerados , Contagem de Colônia Microbiana , DNA Fúngico/química , DNA Fúngico/genética , Filtração , Fungos/classificação , Fungos/genética , Fungos/crescimento & desenvolvimento , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , EspanhaRESUMO
Anaerobic co-digestion is a promising alternative to manage agri-food waste rather than landfilling, composting or incineration. But improvement of methane yield and biodegradability is often required to optimize its economic viability. Biomethanization of agri-food solid waste presents the disadvantage of a slow hydrolytic phase, which might be enhanced by adding a readily digestible substrate such as glycerol. In this study, strawberry extrudate, fish waste and crude glycerol derived from biodiesel manufacturing are mixed at a proportion of 54:5:41, in VS (VS, total volatile solids), respectively. The mesophilic anaerobic co-digestion at lab-scale of the mixture was stable at loads lower than 1.85 g VS/L, reaching a methane yield coefficient of 308 L CH4/kg VS (0 °C, 1 atm) and a biodegradability of 96.7%, in VS. Moreover, the treatment capacity of strawberry and fish waste was increased 16% at adding the crude glycerol. An economic assessment was also carried out in order to evaluate the applicability of the proposed process. Even in a pessimistic scenario, the net balance was found to be positive. The glycerol adding implied a net saving in a range from 25.5 to 42.1 /t if compared to landfill disposal.
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Reatores Biológicos , Peixes , Fragaria , Glicerol , Gerenciamento de Resíduos/métodos , Anaerobiose , Animais , Conservação de Alimentos , Indústria de Processamento de Alimentos , Resíduos Industriais , Metano/metabolismoRESUMO
The biomethanization of sewage sludge has several disadvantages such as low methane yield, poor biodegradability and nutrient imbalance. In this paper, a sewage sludge and strawberry extrudate mixture in a proportion of 40:60 (wet weight) is proposed to improve the viability of the process. The addition of an easily biodegradable co-substrate enhanced the nutrient balance and diluted the heavy metals and inhibitors from sewage sludge. Two different experimental set-ups at lab and semi-pilot scale were employed in order to ensure the reproducibility and significance of the obtained values. Co-digestion improved the stability of the process by decreasing the alkalinity to a mean value of 3215 ± 190 mg CaCO3/L, while maintaining the pH within the optimal range for anaerobic digestion. The methane yield coefficient and biodegradability were 176 L/kg VS (total volatile solids) (0°C, 1 atm) and 81% (VS), respectively. Kinetic parameters decreased at the highest loads, suggesting the occurrence of a slowing down phenomenon. A quality organic amendment with a heavy metal content lower than the limits established under European legislation for agricultural applications was obtained from the digestate of the proposed treatment.
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Reatores Biológicos , Fragaria , Esgotos , Agricultura , Anaerobiose , Fertilizantes , Metano/metabolismo , Eliminação de Resíduos Líquidos/métodos , ResíduosRESUMO
(1) Background: Experiences involve feelings, which, in turn, produce meaning that can become a subjectively lived experience. Therefore, the study of experiences and feelings is essential. INTRODUCTION: We examined the role of narrative-based nursing (NBN) and the poetry of care (PC). OBJECTIVE: To reflect upon the emotions and feelings experienced by nursing students during confinement induced by COVID-19. (2) Methods: This is a qualitative study with a focus on reflexive anthropology, NBN, and PC. SETTING AND PARTICIPANTS: The non-probabilistic sample of incidental, casual, or accessibility type. It consists of 198 students completing their first degree in nursing (the academic year of 2019-2020) of the University of Alicante. (3) Results: Three main categories were considered in the research: For the 'first day', 21 subcategories were identified, and uncertainty was the most frequently noted feeling. For the 'most significant day', 22 subcategories were found, with the explosion of feelings being the most frequent. For the 'last day', 15 subcategories were recorded, with the feeling of relief being the most common. CONCLUSIONS: The NBN and PC are relevant therapeutic tools that facilitate reflection and promote awareness of feelings.
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COVID-19 , Bacharelado em Enfermagem , Estudantes de Enfermagem , Humanos , Estudantes de Enfermagem/psicologia , COVID-19/epidemiologia , Narração , Pesquisa Qualitativa , EmoçõesRESUMO
Ozone has been applied in many processes (drinking water disinfection and wastewater treatment, among others) based on its high degree of effectiveness as a wide-spectrum disinfectant and its potential for the degradation of pollutants and pesticides. Nevertheless, the effects of irrigation with ozonated water on the soil microbial community and plant physiology and productivity at the field scale are largely unknown. Here, we assessed the impact of irrigation with ozonated water on the microbial community of a Mediterranean soil and on Solanum lycopersicum L. agro-physiology and productivity in a greenhouse experiment. For this purpose, we evaluated: i) soil physicochemical properties, soil enzyme activities, and the biomass (through analysis of microbial fatty acids) and diversity (through 16S rRNA gene and ITS2 amplicon sequencing) of the soil microbial community, and ii) the nutrient content, physiology, yield, and fruit quality of tomato plants. Overall, the soil physicochemical properties were slightly affected by the treatments applied, showing some differences between continuous and intermittent irrigation with ozonated water. Only the soil pH was significantly reduced by continuous irrigation with ozonated water at the end of the assay. Biochemical parameters (enzymatic activities) showed no significant differences between the treatments studied. The biomasses of Gram- bacteria and fungi were decreased by intermittent and continuous irrigation with ozonated water, respectively. However, the diversity, structure, and composition of the soil microbial community were not affected by the ozone treatments. Changes in soil properties slightly affected tomato plant physiology but did not affect yield or fruit quality. The stomatal conductance was reduced and the intrinsic water use efficiency was increased by continuous irrigation with ozonated water. Our results suggest that soil health and fertility were not compromised, however ozonated water treatments should be tailored to individual crop conditions to avoid adverse effects.
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Microbiota , Ozônio , Solanum lycopersicum , Irrigação Agrícola , RNA Ribossômico 16S , Solo , Microbiologia do SoloRESUMO
Biochar made-up of dry olive residue (DOR), a biomass resulting from the olive oil extraction industry, has been proposed to be used as a reclamation agent for the recovery of metal contaminated soils. The aim of the present study was to investigate whether the soil application of DOR-based biochar alone or in combination with arbuscular mycorrhizal fungi (AMF) leads to an enhancement in the functionality and abundance of microbial communities inhabiting metal contaminated soils. To study that, a greenhouse microcosm experiment was carried out, where the effect of the factors (i) soil application of DOR-based biochar, (ii) biochar pyrolysis temperature (considering the variants 350 and 500 °C), (iii) soil application dose of biochar (2 and 5%), (iv) soil contamination level (slightly, moderately and highly polluted), (v) soil treatment time (30, 60 and 90 days) and (vi) soil inoculation with Funneliformis mosseae (AM fungus) on ß-glucosidase and dehydrogenase activities, FA (fatty acid)-based abundance of soil microbial communities, soil glomalin content and AMF root colonization rates of the wheat plants growing in each microcosm were evaluated. Biochar soil amendment did not stimulate enzyme activities but increased microbial abundances. Dehydrogenase activity and microbial abundances were found to be higher in less contaminated soils and at shorter treatment times. Biochar pyrolysis temperature and application dose differently affected enzyme activities, but while the first factor did not have a significant effect on glucosidase and dehydrogenase, a higher biochar dose resulted in boosted microbial abundances. Soil inoculation with F. mosseae favored the proliferation of soil AMF community and increased soil glomalin content as well as rates of AMF root colonization. This factor also interacted with many of the others evaluated to significantly affect soil enzyme activities, microbial abundances and AMF community. Our results indicate that the application of DOR-based biochar along with AMF fungi is an appropriate approach to improve the status of microbial communities in soils with a moderate metal contamination at short-term.
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Micorrizas , Olea , Poluentes do Solo , Carvão Vegetal , Fungos , Metais/farmacologia , Micorrizas/química , Oxirredutases , Raízes de Plantas/química , Solo/química , Microbiologia do Solo , Poluentes do Solo/análiseRESUMO
Organic wastes have the potential to be used as soil organic amendments after undergoing a process of stabilization such as composting or as a resource of renewable energy by anaerobic digestion (AD). Both composting and AD are well-known, eco-friendly approaches to eliminate and recycle massive amounts of wastes. Likewise, the application of compost amendments and digestate (the by-product resulting from AD) has been proposed as an effective way of improving soil fertility. The study of microbial communities involved in these waste treatment processes, as well as in organically amended soils, is key in promoting waste resource efficiency and deciphering the features that characterize microbial communities under improved soil fertility conditions. To move beyond the classical analyses of metataxonomic data, the application of co-occurrence network approaches has shown to be useful to gain insights into the interactions among the members of a microbial community, to identify its keystone members and modelling the environmental factors that drive microbial network patterns. Here, we provide an overview of essential concepts for the interpretation and construction of co-occurrence networks and review the features of microbial co-occurrence networks during the processes of composting and AD and following the application of the respective end products (compost and digestate) into soil.
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Anthropogenic activity generates huge amounts of solid organic wastes [...].
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Anaerobic co-digestion of residual cabbage and cauliflower mixed at a ratio 1:1 (w/w) was investigated in two continuously stirred tank reactors under mesophilic conditions to ensure stability and enhanced methane generation. The experiments, including start-up, inoculum acclimatisation and treatment of the waste mixture, were carried out over a 65-day period. The characterisation results showed that the residual mixture contained a high proportion of total Kjeldahl nitrogen (around 37â g N/kg dry weight). The maximum value of methanogenic yield potential was found to be 250 LSTP/kg VS (volatile solid) added, at STP conditions (0°C, 1 atm), by loading organic substrate at a concentration of 1â g VS/L, while its biodegradability was 60%. However, instability of the biomethanisation process was observed after 17 days, which might be a consequence of the high concentration of nitrogen in the reactors. The evaluation of the kinetics of the valorisation process revealed that the waste mixture studied can easily be biodegraded through anaerobic co-digestion.