RESUMO
Dietary supplementation with triglyceride tributyrin (TBT), a butyrate precursor, has been associated with beneficial effects on fish health and improvements in the ability of carnivorous fish to tolerate higher levels of plant-based protein. In this study, we aimed to investigate the effects of a plant-based diet supplemented with TBT on the structural diversity and putative function of the digesta-associated bacterial communities of rainbow trout (Oncorhynchus mykiss). In addition to this, we also assessed the response of fish gut digestive enzyme activities and chyme metabolic profile in response to TBT supplementation. Our results indicated that TBT had no significant effects on the overall fish gut bacterial communities, digestive enzyme activities or metabolic profile when compared with non-supplemented controls. However, a more in-depth analysis into the most abundant taxa showed that diets at the highest TBT concentrations (0.2% and 0.4%) selectively inhibited members of the Enterobacterales order and reduced the relative abundance of a bacterial population related to Klebsiella pneumoniae, a potential fish pathogen. Furthermore, the predicted functional analysis of the bacterial communities indicated that increased levels of TBT were associated with depleted KEGG pathways related to pathogenesis. The specific effects of TBT on gut bacterial communities observed here are intriguing and encourage further studies to investigate the potential of this triglyceride to promote pathogen suppression in the fish gut environment, namely in the context of aquaculture.
Assuntos
Microbioma Gastrointestinal , Oncorhynchus mykiss , Animais , Oncorhynchus mykiss/metabolismo , Suplementos Nutricionais/análise , Dieta , Bactérias , Triglicerídeos/metabolismo , Ração Animal/análiseRESUMO
The amount of available light plays a key role in the growth and development of microbial communities. In the present study, we tested to what extent sponge-associated prokaryotic communities differed between specimens of the sponge species Cinachyrella kuekenthali and Xestospongia muta collected in dimly lit (caves and at greater depths) versus illuminated (shallow water) habitats. In addition to this, we also collected samples of water, sediment, and another species of Cinachyrella, C. alloclada. Overall, the biotope (sponge host species, sediment, and seawater) proved the major driver of variation in prokaryotic community composition. The light habitat, however, also proved a predictor of compositional variation in prokaryotic communities of both C. kuekenthali and X. muta. We used an exploratory technique based on machine learning to identify features (classes, orders, and OTUs), which distinguished X. muta specimens sampled in dimly lit versus illuminated habitat. We found that the classes Alphaproteobacteria and Rhodothermia and orders Puniceispirillales, Rhodospirillales, Rhodobacterales, and Thalassobaculales were associated with specimens from illuminated, i.e., shallow water habitat, while the classes Dehalococcoidia, Spirochaetia, Entotheonellia, Nitrospiria, Schekmanbacteria, and Poribacteria, and orders Sneathiellales and Actinomarinales were associated with specimens sampled from dimly lit habitat. There was, however, considerable variation within the different light habitats highlighting the importance of other factors in structuring sponge-associated bacterial communities.
Assuntos
Microbiota , Poríferos , Animais , Biodiversidade , Filogenia , Bactérias/genética , Água do Mar/microbiologia , Água , RNA Ribossômico 16S/genéticaRESUMO
Calcareous sponges are an often overlooked element of sponge communities. In contrast to most other sponges, calcareous sponges produce calcium carbonate spicules, as opposed to the siliceous spicules of most sponges. Here, we investigated the bacterial communities of 17 sponge species, including type and paratype specimens of recently described calcareous species, sampled off the remote island of Rodrigues, in the Indian Ocean. The main axis of variation in a PCO analysis of all samples separated noncalcareous sponge species, including Axinyssa aplysinoides, Cinachyrella aff. australiensis, Petrosia seychellensis, Ircinia aff. variabilis, Spongia ceylonensis, Plakinastrella aff. clipptertonensis, Agelas aff. ceylonica, Agelas aff. mauritiana, and Hyrtios erectus from calcareous sponges, the noncalcareous Biemna tubulata, sediment, and seawater. Overall, the bacterial communities of calcareous sponges revealed unique prokaryotic profiles with low abundances of several bacterial phyla, and relatively high abundances of other taxa, for example, the phyla Fibrobacterota, Proteobacteria, and the SAR324 clade, the class Alphaproteobacteria, and orders Cytophagales and Cyanobacteriales, although there was considerable variation among species. Calcareous sponges also had a high dominance of unknown bacterial operational taxonomic units (OTUs). Considering the unique nature of these communities, further studies are needed to better understand the environmental and ecological drivers of calcareous sponge-associated bacterial communities and their relevance as potential sources of novel microbes of biotechnological interest.
Assuntos
Biodiversidade , Poríferos , Animais , Bactérias/genética , Células Procarióticas , Água do Mar/microbiologia , Oceano Índico , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
Recent studies have shown that the addition of non-viable microbial biomass or their components (postbiotics) to fish feed can modulate the gut microbiome and positively influence fish health in aquaculture systems. However, no information was hitherto available on the use of non-viable microbial biomass to manipulate aquaculture bacterioplankton communities. To fill this gap, here we used an in vitro model to assess the effects of heat-killed biomasses of an antagonistic strain Pseudoalteromonas rubra SubTr2 and a non-antagonist strain Escherichia coli DH5α on bacterioplankton communities of a recirculating aquaculture system (RAS). Our results showed that these biomasses can have generalist and species-specific effects on aquaculture bacterioplankton structure and function. In addition, they enriched the abundance of bacterial predators, reduced bacterial load and potentially influenced nutrient cycling and pathogen development in aquaculture water. Despite its preliminary nature, for the first time, this study showed that heat-killed microbial biomass has potential application as an in situ modulator of bacterioplankton in aquaculture systems.
Assuntos
Aquicultura , Temperatura Alta , Animais , Biomassa , RNA Ribossômico 16S , Aquicultura/métodos , Bactérias/genética , Organismos AquáticosRESUMO
Dietary glycerol supplementation in aquaculture feed is seen as an alternative and inexpensive way to fuel fish metabolism, attenuate metabolic utilization of dietary proteins and, subsequently, reduce nitrogen excretion. In this study, we evaluated the impact of dietary glycerol supplementation on nitrogen excretion of European seabass (Dicentrarchus labrax) and its effects on metabolite profile and bacterial community composition of gut digesta. These effects were evaluated in a 60-day trial with fish fed diets supplemented with 2.5% or 5% (w/w) refined glycerol and without glycerol supplementation. Nuclear magnetic resonance spectroscopy and high-throughput 16S rRNA gene sequencing were used to characterize the effects of glycerol supplementation on digesta metabolite and bacterial community composition of 6-h postprandial fish. Our results showed that ammonia excretion was not altered by dietary glycerol supplementation, and the highest glycerol dosage was associated with significant increases in amino acids and a decrease of ergogenic creatine in digesta metabolome. Concomitantly, significant decreases in putative amino acid degradation pathways were detected in the predicted metagenome analysis, suggesting a metabolic shift. Taxon-specific analysis revealed significant increases in abundance of some specific genera (e.g., Burkholderia and Vibrio) and bacterial diversity. Overall, our results indicate glycerol supplementation may decrease amino acid catabolism without adversely affecting fish gut bacterial communities.Key points⢠Glycerol can be an inexpensive and energetic alternative in fish feed formulations.⢠Glycerol did not affect nitrogen excretion and gut bacteriome composition.⢠Glycerol reduced uptake of amino acids and increased uptake of ergogenic creatine.⢠Glycerol reduced putative amino acid degradation pathways in predicted metagenome.
Assuntos
Bass , Microbioma Gastrointestinal , Ração Animal/análise , Animais , Suplementos Nutricionais , Glicerol , RNA Ribossômico 16S/genéticaRESUMO
In the present study, we used Illumina sequencing to explore the prokaryote communities of 17 demosponge species and how they compare with bacterial mat, sediment and seawater samples (all sampled from coral reef habitat in Taiwan and Thailand). The studied sponge species formed three clusters. Operational taxonomic unit (OTU) richness and evenness were by far highest in the sediment and bacterial mat biotopes. There were pronounced differences in OTU richness and evenness among clusters and also considerable variation among certain host species within clusters. Additionally, the relative abundance of some prokaryotic taxa also differed among clusters with Poribacteria, e.g., being recorded in all sponge species, but with very low relative abundances in species of two of the three clusters. This sponge-associated phylum was, however, recorded at relatively high mean abundance in bacterial mat samples, which also housed relatively high abundances of actinobacterial and Chloroflexi members. Our results support high microbial abundance (HMA) status of the species Aaptos lobata, Hyrtios erectus, Pseudoceratina purpurea and Xestospongia testudinaria and low microbial abundance (LMA) status of the species Acanthella cavernosa, Echinodictyum asperum, Jaspis splendens, Ptilocaulis spiculifer, Stylissa carteri and Suberites diversicolor. Other species (Agelas cavernosa, Agelas nemoechinata, Acanthostylotella cornuta, Paratetilla sp., Hymeniacidon sp. and Haliclona cymaeformis) deviated somewhat from the typical HMA/LMA dichotomy and formed a strongly supported cluster.
Assuntos
Antozoários/microbiologia , Bactérias/classificação , Bactérias/isolamento & purificação , Poríferos/microbiologia , Animais , Bactérias/genética , Biodiversidade , Recifes de Corais , Ecossistema , Filogenia , RNA Ribossômico 16S/genética , Água do Mar/microbiologia , Taiwan , TailândiaRESUMO
AIM: To evaluate the interactive effects of oil contamination and chemical dispersant application on bacterial composition and sediment remediation of an estuarine port environment. METHODS AND RESULTS: A multifactorial controlled microcosm experiment was set up using sediment cores retrieved from an estuarine port area located at Ria de Aveiro lagoon (Aveiro, Portugal). An oil spill with and without chemical dispersant addition was simulated. Sediment oil hydrocarbon concentrations and benthic bacterial community structure were evaluated by GC-MS and 16S rRNA high-throughput sequencing respectively. Although initially (first 10 days) chemical dispersion of oil enhanced the concentrations of the heavier polycyclic aromatic hydrocarbons and of the C22 -C30 alkane group, with time (21 days), no significant differences in hydrocarbon concentrations were detected among treatments. Moreover, no significant changes were detected in the structure of sediment bacterial communities, which mainly consisted of operational taxonomic units related to hydrocarbon-contaminated marine environments. We hypothesize that the environmental background of the sampling site preconditioned the communities' response to additional contamination. CONCLUSION: This experimental microcosm study showed that the chemical dispersion of oil did not influence sediment remediation or bacterial community composition. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study showed that chemical dispersion of oil may not improve the remediation of port sediments. Further studies are needed to investigate the impact of chemical dispersants in combination with bioremediation strategies on the process of sediment remediation in port areas.
Assuntos
Sedimentos Geológicos/microbiologia , Microbiota , Poluição por Petróleo/análise , Petróleo/análise , Poluentes Químicos da Água/análise , Bactérias/classificação , Bactérias/genética , Biodegradação Ambiental , Monitoramento Ambiental , Sedimentos Geológicos/química , Hidrocarbonetos/análise , PortugalRESUMO
Previously, it was believed that the prokaryote communities of typical 'low-microbial abundance' (LMA) or 'non-symbiont harboring' sponges were merely subsets of the prokaryote plankton community. Recent research has, however, shown that these sponges are dominated by particular clades of Proteobacteria or Cyanobacteria. Here, we expand on this research and assess the composition and putative functional profiles of prokaryotic communities from LMA sponges collected in two ecosystems (coral reef and hydrothermal vent) from vicinal islands of Taiwan with distinct physicochemical conditions. Six sponge species identified as Acanthella cavernosa (Bubarida), Echinodictyum asperum, Ptilocaulis spiculifer (Axinellida), Jaspis splendens (Tetractinellida), Stylissa carteri (Scopalinida) and Suberites sp. (Suberitida) were sampled in coral reefs in the Penghu archipelago. One sponge species provisionally identified as Hymeniacidon novo spec. (Suberitida) was sampled in hydrothermal vent habitat. Each sponge was dominated by a limited set of operational taxonomic units which were similar to sequences from organisms previously obtained from other LMA sponges. There was a distinct bacterial community between sponges collected in coral reef and in hydrothermal vents. The putative functional profile revealed that the prokaryote community from sponges collected in hydrothermal vents was significantly enriched for pathways related to DNA replication and repair.
Assuntos
Bactérias/isolamento & purificação , Fontes Hidrotermais/microbiologia , Poríferos/microbiologia , Animais , Bactérias/classificação , Bactérias/genética , Biodiversidade , Recifes de Corais , Ecossistema , Filogenia , Poríferos/classificação , TaiwanRESUMO
Objetivo: identificar os sentimentos despertados nas mulheres frente ao diagnóstico de câncer de mama. Método: trata-se de um estudo qualitativo, realizado no ambulatório de oncologia de um hospital universitário, com 11 mulheres diagnosticadas com câncer de mama e idade entre 43 e 58 anos. A coleta de dados foi realizada por meio de entrevista semiestruturada, de maio a julho de 2015. Os dados foram analisados e interpretados conforme a análise de conteúdo. Resultados: após a análise emergiram três categorias: o impacto do diagnóstico; a vivência prévia da doença, o autoconhecimento e sua aceitação; esperança embasada na fé em Deus. Considerações Finais: a maioria das mulheres demonstraram-se extremamente sensibilizadas com o diagnóstico de câncer de mama e aflitas diante da incerteza da morte; outras, por já terem vivenciado a doença em um ente próximo, sentiram-se mais fortes e reagiram melhor ao diagnóstico.
Objective: to identify the feelings aroused by women in the diagnosis of breast cancer. Method: thisis a qualitative study, performed at the oncology outpatient clinic of a university hospital, with 11women diagnosed with breast cancer and aged between 43 and 58 years. Data collection wasperformed through a semi-structured interview, from May to July 2015. Data were analyzed andinterpreted according to content analysis. Results: three categories emerged after the analysis: theimpact of the diagnosis; the previous experience of the disease, self-knowledge and its acceptance; hope grounded in faith. Final Considerations: most women were extremely sensitive to the diagnosisof breast cancer and afflicted by the uncertainty of death, others because they had experienced thedisease in a nearby entity felt stronger and reacted better to the diagnosis.
Assuntos
Humanos , Diagnóstico , Enfermagem , Neoplasias da MamaRESUMO
This study aimed to carry out the pharmacotherapeutic follow-up of patients with depression and to assess its impact on the resilience of the patients. Patients were followed-up for 8 months. The pharmacist evaluated depressive symptoms, resilience, and the need for pharmaceutical intervention. The measurement tools used were the Dader method, PHQ-9, and a resilience scale. Data were analysed using BioStat 5.0 software and the performing of the Wilcoxon and Pearson correlation tests. There was a reduction in the rate of depressive symptoms from 12.9 to 5.2 (P<.0001), and an increase in the resilience score from 112.4 to 149.0 (P<.0001). Pharmaceutical interventions were made to resolve the drug related problems in the form of oral communication between pharmacist-patient or pharmacist-patient-doctor. The pharmaceutical care was effective in decreasing depression and contributed to the increased resilience of patients.
Assuntos
Depressão/diagnóstico , Depressão/tratamento farmacológico , Resiliência Psicológica , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação de SintomasRESUMO
OBJECTIVES: Candida parapsilosis is a healthcare-related fungal pathogen particularly common among immunocompromised patients. Our understanding of antifungal resistance mechanisms in C. parapsilosis remains very limited. We previously described an azole-resistant strain of C. parapsilosis (BC014RPSC), obtained following exposure in vitro to posaconazole. Resistance was associated with overexpression of ergosterol biosynthetic genes (ERG genes), together with the transcription factors UPC2 (CPAR2-207280) and NDT80 (CPAR2-213640). The aim of this study was to identify the mechanisms underlying posaconazole resistance of the BC014RPSC strain. METHODS: To identify the causative mutation, we sequenced the genomes of the susceptible (BC014S) and resistant (BC014RPSC) isolates, using Illumina technology. Ergosterol content was assessed in both strains by mass spectrometry. UPC2 and NDT80 genes were deleted in BC014RPSC strain. Mutants were characterized regarding their azole susceptibility profile and ERG gene expression. RESULTS: One homozygous missense mutation (R135I) was found in ERG3 (CPAR2-105550) in the azole-resistant isolate. We show that Erg3 activity is completely impaired, resulting in a build up of sterol intermediates and a failure to generate ergosterol. Deleting UPC2 and NDT80 in BC014RPSC reduces the expression of ERG genes and restores susceptibility to azole drugs. CONCLUSIONS: A missense mutation in the ERG3 gene results in azole resistance and up-regulation of ERG genes expression. We propose that this mutation prevents the formation of toxic intermediates when cells are treated with azoles. Resistance can be reversed by deleting Upc2 and Ndt80 transcription factors. UPC2 plays a stronger role in C. parapsilosis azole resistance than does NDT80.
Assuntos
Antifúngicos/farmacologia , Azóis/farmacologia , Candida parapsilosis/efeitos dos fármacos , Farmacorresistência Fúngica , Ergosterol/metabolismo , Mutação de Sentido Incorreto , Fatores de Transcrição/metabolismo , Candida parapsilosis/química , Candida parapsilosis/genética , Ergosterol/análise , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Deleção de Genes , Perfilação da Expressão Gênica , Espectrometria de Massas , Testes de Sensibilidade Microbiana , Oxirredutases/genética , Oxirredutases/metabolismo , Provitaminas/metabolismo , Fatores de Transcrição/genética , Sequenciamento Completo do GenomaRESUMO
Titanium dental implants are commonly used due to their biocompatibility and biochemical properties; blasted acid-etched Ti is used more frequently than smooth Ti surfaces. In this study, physico-chemical characterisation revealed important differences in roughness, chemical composition and hydrophilicity, but no differences were found in cellular in vitro studies (proliferation and mineralization). However, the deposition of proteins onto the implant surface might affect in vivo osseointegration. To test that hypothesis, protein layers formed on discs of both surface type after incubation with human serum were analysed. Using mass spectrometry (LC/MS/MS), 218 proteins were identified, 30 of which were associated with bone metabolism. Interestingly, Apo E, antithrombin and protein C adsorbed mostly onto blasted and acid-etched Ti, whereas the proteins of the complement system (C3) were found predominantly on smooth Ti surfaces. These results suggest that physico-chemical characteristics could be responsible for the differences observed in the adsorbed protein layer.
Assuntos
Proteínas Sanguíneas/análise , Implantes Dentários , Proteômica , Titânio/química , Adsorção , Animais , Humanos , Microscopia Eletrônica de Varredura , Osseointegração , Propriedades de Superfície , Espectrometria de Massas em TandemRESUMO
In the present study, we used 16S rRNA barcoded pyrosequencing to investigate to what extent monospecific stands of different salt marsh plant species (Juncus maritimus and Spartina maritima), sampling site and temporal variation affect sediment bacterial communities. We also used a bioinformatics tool, PICRUSt, to predict metagenome gene functional content. Our results showed that bacterial community composition from monospecific stands of both plant species varied temporally, but both host plant species maintained compositionally distinct communities of bacteria. Juncus sediment was characterised by higher abundances of Alphaproteobacteria, Myxococcales, Rhodospirillales, NB1-j and Ignavibacteriales, while Spartina sediment was characterised by higher abundances of Anaerolineae, Synechococcophycidae, Desulfobacterales, SHA-20 and Rhodobacterales. The differences in composition and higher taxon abundance between the sediment bacterial communities of stands of both plant species may be expected to affect overall metabolic diversity. In line with this expectation, there were also differences in the predicted enrichment of selected metabolic pathways. In particular, bacterial communities of Juncus sediment were predicted to be enriched for pathways related to the degradation of various (xenobiotic) compounds. Bacterial communities of Spartina sediment in turn were predicted to be enriched for pathways related to the biosynthesis of various bioactive compounds. Our study highlights the differences in composition and predicted functions of sediment-associated bacterial communities from two different salt marsh plant species. Loss of salt marsh habitat may thus be expected to both adversely affect microbial diversity and ecosystem functioning and have consequences for environmental processes such as nutrient cycling and pollutant remediation.
Assuntos
Bactérias/classificação , Sedimentos Geológicos/microbiologia , Magnoliopsida/microbiologia , Metagenômica , Consórcios Microbianos , Poaceae/microbiologia , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodiversidade , Código de Barras de DNA Taxonômico , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Ecossistema , Geografia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Áreas AlagadasRESUMO
Recalcitrant polycyclic aromatic hydrocarbons (PAHs) released into seawater end up in the deep sea sediments (DSSs). However, their fate here is often oversimplified by theoretical models. Biodegradation of PAHs in DSSs, is assumed to be similar to biodegradation in surface habitats, despite high hydrostatic pressures and low temperatures that should significantly limit PAH biodegradation. Bacteria residing in the DSSs (related mainly to α- and γ-Proteobacteria) have been shown to or predicted to possess distinct genes, enzymes and metabolic pathways, indicating an adaptation of these bacterial communities to the psychro-peizophilic conditions of the DSSs. This work summarizes some of the most recent research on DSS hydrocarbonoclastic populations and mechanisms of PAH degradation and discusses the challenges posed by future high CO2 and UV climate scenarios on biodegradation of PAHs in DSSs.
Assuntos
Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Poluentes Químicos da Água/metabolismo , Bactérias/metabolismo , Biodegradação Ambiental , Ecossistema , Sedimentos Geológicos/microbiologia , Água do Mar/microbiologiaRESUMO
The main goal of this study was to evaluate the efficiency of phage therapy against one of the most common multidrug-resistant (MDR) agents of skin infections, Pseudomonas aeruginosa. A phage suspension [10(8) plaque-forming units (PFU) mL(-1)] was obtained using the clinical strain P. aeruginosa 709 as the host. The ability of the phage to inactivate P. aeruginosa was evaluated in vitro and ex vivo (human skin), using a multiplicity of infection (MOI) of 0.5 to 50. In the presence of the phage, the density of P. aeruginosa 709 [10(5) colony-forming units (CFU) mL(-1)] in the human skin decreased by 4 logs after 2 h of incubation. The application of a second dose of phage did not increase the efficiency of the therapy. This study indicates that the topical application of phage PA709 efficiently inactivates MDR P. aeruginosa 709. The high efficiency in the inactivation of MDR P. aeruginosa 709, its considerable host range (infection of 30 % of the P. aeruginosa isolates) and its high stability in buffer and ex vivo human skin make this phage very promising for the treatment of P. aeruginosa skin infections. The phage-bacteria interactions were examined in vitro and in ex vivo in order to provide a basis for the selection of the most suitable protocol for subsequent in vivo experiments.
Assuntos
Terapia Biológica/métodos , Farmacorresistência Bacteriana Múltipla , Infecções por Pseudomonas/terapia , Fagos de Pseudomonas , Pseudomonas aeruginosa/virologia , Dermatopatias Bacterianas/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Contagem de Colônia Microbiana , Feminino , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Dermatopatias Bacterianas/microbiologia , Resultado do TratamentoRESUMO
We compare the environmental characteristics and bacterial communities associated with two rushes, Juncus maritimus and Bolboschoenus maritimus, and adjacent unvegetated habitat in a salt marsh subjected to historical mercury pollution. Mercury content was higher in vegetated than unvegetated habitat and increased with sampling depth. There was also a significant relationship between mercury concentration and bacterial composition. Habitat (Juncus, Bolboschoenus or unvegetated), sample depth, and the interaction between both, however, explained most of the variation in composition (~70%). Variation in composition with depth was most prominent for the unvegetated habitat, followed by Juncus, but more constrained for Bolboschoenus habitat. This constraint may be indicative of a strong plant-microbe ecophysiological adaptation. Vegetated habitat contained distinct bacterial communities associated with higher potential activity of aminopeptidase, ß-glucosidase and arylsulphatase and incorporation rates of (14)C-glucose and (14)C-acetate. Communities in unvegetated habitat were, in contrast, associated with both higher pH and proportion of sulphate reducing bacteria.
Assuntos
Fenômenos Fisiológicos Bacterianos/efeitos dos fármacos , Cyperaceae/fisiologia , Magnoliopsida/fisiologia , Mercúrio/toxicidade , Fenômenos Fisiológicos Vegetais , Poluentes Químicos da Água/toxicidade , Áreas Alagadas , Bactérias/classificação , Bactérias/genética , Ecossistema , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Concentração de Íons de Hidrogênio , Mercúrio/análise , RNA Ribossômico 16S , Fatores de Tempo , Poluentes Químicos da Água/análiseRESUMO
AIMS: To assess the variability in UV-B (280-320 nm) sensitivity of selected bacterial isolates from the surface microlayer and underlying water of the Ria de Aveiro (Portugal) estuary and their ability to recover from previous UV-induced stress. METHODS AND RESULTS: Bacterial suspensions were exposed to UV-B radiation (3·3 W m⻲). Effects on culturability and activity were assessed from colony counts and (3) H-leucine incorporation rates, respectively. Among the tested isolates, wide variability in UV-B-induced inhibition of culturability (37·4-99·3%) and activity (36·0-98·0%) was observed. Incubation of UV-B-irradiated suspensions under reactivating regimes (UV-A, 3·65 W m⻲; photosynthetic active radiation, 40 W m⻲; dark) also revealed diversity in the extent of recovery from UV-B stress. Trends of enhanced resistance of culturability (up to 15·0%) and enhanced recovery in activity (up to 52·0%) were observed in bacterioneuston isolates. CONCLUSIONS: Bacterioneuston isolates were less sensitive and recovered more rapidly from UV-B stress than bacterioplankton isolates, showing enhanced reduction in their metabolism during the irradiation period and decreased culturability during the recovery process compared to bacterioplankton. SIGNIFICANCE AND IMPACT OF THE STUDY: UV exposure can affect the diversity and activity of microbial communities by selecting UV-resistant strains and alter their metabolic activity towards protective strategies.
Assuntos
Bactérias/efeitos da radiação , Plâncton/efeitos da radiação , Raios Ultravioleta , Microbiologia da Água , Bactérias/isolamento & purificação , Plâncton/isolamento & purificação , Portugal , Água do Mar/microbiologiaRESUMO
The effects of sewage sludge selectively enriched with Cd and Zn, both singly and in combination, on the bacterial, fungal, Alphaproteobacteria and Actinobacteria communities of a soil under arable or grassland management were studied with a PCR-DGGE approach. The effects of Cd and Zn were evaluated after a short time (7 d) when the Cd and Zn solubility were low and the C availability was high, and again after 180 d when the labile sludge C was mineralized and the effects of heavy metals predominated. In the arable soil all treatments induced significant short-term changes in the studied microbial groups, and long-term changes were observed in Actinobacteria and fungal communities. In the grassland soil, all treatments induced significant short-term changes in the studied microbial groups except for Alphaproteobacteria and fungi, and long-term effects on the actinobacteria and fungal communities. It was concluded that incorporation of Cd- and Zn-rich sludge into soils may have both short- and long-term effects on various bacterial phylogenetic groups whereas the metals may be better tolerated by the dominant soil fungi. In this study the impact was greater in arable than in grassland soil.
Assuntos
Actinobacteria/efeitos dos fármacos , Alphaproteobacteria/efeitos dos fármacos , Cádmio/toxicidade , Fungos/efeitos dos fármacos , Esgotos , Microbiologia do Solo , Zinco/toxicidade , Actinobacteria/isolamento & purificação , Alphaproteobacteria/isolamento & purificação , Cádmio/análise , Eletroforese em Gel de Gradiente Desnaturante , Fungos/isolamento & purificação , Reação em Cadeia da Polimerase , RNA Bacteriano/genética , RNA Fúngico/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 18S/genética , Esgotos/química , Esgotos/microbiologia , Microbiologia do Solo/normas , Zinco/análiseRESUMO
The effects of shrimp farm effluents on bacterial communities in mangroves have been infrequently reported. Classic and molecular biology methods were used to survey bacterial communities from four mangroves systems. Water temperature, salinity, pH, total heterotrophic bacteria and maximum probable numbers of Vibrio spp. were investigated. Genetic profiles of bacterial communities were also characterized by polymerase chain reaction (PCR) amplification of eubacterial and Vibrio 16S rDNA using denaturing gradient gel electrophoresis (DGGE). Highest heterotrophic counts were registered in the mangrove not directly polluted by shrimp farming. The Enterobacteriaceae and Chryseomonas luteola dominated the heterotrophic isolates. Vibrio spp. pathogenic to humans and shrimps were identified. Eubacterial genetic profiles suggest a shared community structure independent of mangrove system. Vibrio genetic profiles were mangrove specific. Neither microbial counts nor genetic profiling revealed a significant decrease in species richness associated with shrimp farm effluent. The complex nature of mangrove ecosystems and their microbial communities is discussed.
Assuntos
Fenômenos Fisiológicos Bacterianos , Biodiversidade , Monitoramento Ambiental , Água do Mar/microbiologia , Aquicultura , Bactérias/genética , Bactérias/isolamento & purificação , Brasil , Contagem de Colônia Microbiana/métodos , Filogenia , RNA Ribossômico 16S/genética , Rhizophoraceae , Água do Mar/química , Vibrio/genética , Vibrio/isolamento & purificaçãoRESUMO
As is the case for Saccharomyces boulardii, Saccharomyces cerevisiae W303 protects Fisher rats against cholera toxin (CT). The addition of glucose or dinitrophenol to cells of S. boulardii grown on a nonfermentable carbon source activated trehalase in a manner similar to that observed for S.cerevisiae. The addition of CT to the same cells also resulted in trehalase activation. Experiments performed separately on the A and B subunits of CT showed that both are necessary for activation. Similarly, the addition of CT but not of its separate subunits led to a cyclic AMP (cAMP) signal in both S. boulardii and S. cerevisiae. These data suggest that trehalase stimulation by CT probably occurred through the cAMP-mediated protein phosphorylation cascade. The requirement of CT subunit B for both the cAMP signal and trehalase activation indicates the presence of a specific receptor on the yeasts able to bind to the toxin, a situation similar to that observed for mammalian cells. This hypothesis was reinforced by experiments with 125I-labeled CT showing specific binding of the toxin to yeast cells. The adhesion of CT to a receptor on the yeast surface through the B subunit and internalization of the A subunit (necessary for the cAMP signal and trehalase activation) could be one more mechanism explaining protection against the toxin observed for rats treated with yeasts.