Browsing by Author "Oliveira, Rui S."
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- 3rd International Congress of Environmental Health: Proceedings BookPublication . Vieira Da Silva, Manuela; Oliveira, Rui S.; Rodrigues, Matilde; Nunes, Mafalda; Santos, Joana; Carvalhais, C.; Rebelo, Andreia; Freitas, Marisa; Xavier, AnaThis third edition addresses to ‘Emerging risks and challenges for the environment, health and safety’ and intended as a guide to the various symposiums and workshops, to provide all present the most recent scientific and technological advances in the areas: Occupational Health and Toxicology; Exposure to Nanoparticles; Assessment and Risk Management; Occupational Safety; Exposure to Bioaerosols; Environment and Sustainability; Food Safety and Public Health.
- Actinobacteria as new probiotics for preventing fish diseases in aquaculturePublication . Santos, Matilde; Girão, Mariana; Oliveira, Rui S.; Carvalho, FátimaIn order to meet the food needs of a constantly growing world population, aquaculture emerges as the fastest growing food production sector. However, disease outbreaks due to opportunistic bacterial pathogens cause large losses. Antibacterial chemicals used indiscriminately have resulted in resistant bacteria and antibiotic resistance genes. Ecological solutions such as probiotics are needed. Probiotics are microorganisms introduced into another organism that can have beneficial effects on the host as well as improve the external environment. Actinobacteria are an important biotechnological resource, as they produce a great diversity of secondary metabolites with a high range of bioactivities, including antimicrobial. The aim of this study was to explore the probiotic potential of some marine actinobacteria to prevent aquaculture fish diseases. For this, a screening of antimicrobial activity was performed using agar-based disk diffusion and Minimum Inhibitory Concentration (MIC) assays, against three Gram-negative bacterial fish pathogens: Aeromonas hydrophila, Edwardsiella tarda and Pseudomonas anguilliseptica. A total of 54 out of 103 actinobacterial extracts tested, presented bioactivity against these microorganisms, so that the growth of all three Gram-negative pathogens used was inhibited. The diameter of the inhibition halos varied between 8 and 20 mm. Tested extracts presented MIC values of 1000 µg/ml, except for Isoptericola chiayiensis (500 µg/ml). Microbispora bryophytorum, Isoptericola chiayiensis and Nocardia nova were some of the bacteria with the most promising results. Overall, actinobacteria associated with seaweed proved to be a potential source of probiotics to inhibit pathogens in aquaculture fish.
- Anticancer potential of spores of the soil fungus Pisolithus tinctoriusPublication . Oliveira, Rui S.; Alves, Ricardo; Preto, Marco; Martins, RosárioCancer is one of the major causes of death worldwide being the search for new anticancer drugs essential for the treatment of this disease. The sporocarps of the soil fungus Pisolithus tinctorius contain pisosterol, a triterpene that has been shown to have antitumor activity against some cancer cell lines. Nevertheless, no studies have focused on the anticancer potential of other structures such as spores, and so the anticancer potential of P. tinctorius, remains largely unknown. The main objective of this study was to evaluate the potential of P. tinctorius spores as a source of anticancer compounds.
- Application of microbial Inoculants as a sustainable practice for the production of grain legumes under water stressPublication . Carvalho, Patrícia; Marques, Sonya; Nunes, Mafalda; Marques, Guilhermina; Oliveira, Rui S.Grain legumes contain high level of protein and adequate proportions of carbohydrates and oil, making them valuable as human food. Unlike protein products of animal origin, legumes contain much less fat, which makes them healthier. The nutritional value of legumes has been associated with reduction of incidence of chronic diseases such as cancer, type-2 diabetes and heart disease. Arbuscular mycorrhizal fungi (AMF) and nitrogen fixing bacteria (NFB) are beneficial soil microorganisms that can improve plant nutrition and increase drought tolerance.
- Arbuscular mycorrhizal fungi are an alternative to the application of chemical fertilizer in the production of the medicinal and aromatic plantCoriandrum sativumLPublication . Oliveira, Rui S.; Ma, Ying; Rocha, Inês; Carvalho, Maria F.; Vosátka, Miroslav; Freitas, HelenaThe widespread use of agrochemicals is detrimental to the environment and may exert harmful effects on human health. The consumer demand for organic food plants has been increasing. There is thus a rising need for alternatives to agrochemicals that can foster sustainable plant production. The aim of this study was to evaluate the potential use of an arbuscular mycorrhizal (AM) fungus as an alternative to application of chemical fertilizer for improving growth performance of the medicinal and aromatic plant Coriandrum sativum. Plants were inoculated with the AM fungus Rhizophagus irregularis BEG163 and/or supplemented with a commercial chemical fertilizer (Plant Marvel, Nutriculture Bent Special) in agricultural soil. Plant growth, nutrition, and development of AM fungus were assessed. Plants inoculated with R. irregularis and those supplemented with chemical fertilizer displayed significantly improved growth performances when compared with controls. There were no significant differences in total fresh weight between plants inoculated with R. irregularis or those supplemented with chemical fertilizer. Leaf chlorophyll a + b (82%), shoot nitrogen (44%), phosphorus (254%), and potassium (27%) concentrations increased in plants inoculated with R. irregularis compared to controls. Application of chemical fertilizer inhibited root mycorrhizal colonization and the length of the extraradical mycelium of R. irregularis. Inoculation with R. irregularis was equally or more efficient than application of chemical fertilizer in promoting growth and nutrition of C. sativum. AM fungi may thus contribute to improve biologically based production of food plants and reduce the dependence on agrochemicals in agriculture.
- Arbuscular mycorrhizal fungi are more efficient than chemical fertilisers in the production of essential oils of common thyme (Thymus vulgaris )Publication . Oliveira, Rui S.; Moreira, Vanessa; Nunes, Mafalda; Rocha, Inês; Carvalho, M. Fátima; Vosátka, Miroslav; Cavaleiro, Carlos; Salgueiro, Lígia; Freitas, HelenaCommon thyme is an aromatic plant with medicinal, cosmetics and culinary uses. Due to its antimicrobial, antioxidant/antiradical and antitumor activity the essential oils of common thyme are in great demand (Nikolić et al., 2014). A significant part of the production of aromatic plants relies on the use of chemical fertilisers, which when applied in large scale can have significant environmental consequences (Malik et al., 2011). Arbuscular mycorrhizal fungi (AMF) are a group of soil microorganisms that forms mutualistic symbioses that can benefit plants by improving the uptake of mineral nutrients, mineralising organic nutrients and conferring drought resistance (Oliveira et al., 2005).AMF have the potential to be inoculatedin the production of common thyme as an ecotechnological tool to reduce the input of chemicals fertilisers.
- Arbuscular mycorrhizal fungi can improve the growth of aromatic plants and prevent soil erosion after forest firesPublication . Duarte, Beatriz; Soares, Sara; Oliveira, Rui S.Forest fires are regarded as one of the major environmental problems in Portugal. Among their negative impacts is loss of green area and soil structure damage, which increase soil erodibility. Adequate soil structure is essential to support plant and animal life and to moderate environmental quality with particular emphasis on soil carbon sequestration and water quality (Certini, 2005). After a forest fire the ecosystem has the capacity to recover through ecological succession. This is, however, a slow process and there is the need for human intervention in order to mitigate the negative impacts of forest fires. Aromatic plants, such as rosemary, are among the first to grow in post-fire Mediterranean forest ecosystems (Luis et al., 2006). This together with their commercial value makes these plants attractive candidates to be used in the first stages of restoration of burned forest soils. Arbuscular mycorrhizal fungi (AMF) are a group of soil microorganisms that forms mutualistic symbioses that can benefit plants by improving the uptake of mineral nutrients, mineralising organic nutrients and conferring drought resistance (Oliveira et al., 2005).AMF have also the capacity to promote soil aggregation by several mechanisms including the release of soil binding agents.
- Bioaugmentation with Endophytic Bacterium E6S Homologous to Achromobacter piechaudii Enhances Metal Rhizoaccumulation in Host Sedum plumbizincicolaPublication . Ma, Ying; Zhang, Chang; Oliveira, Rui S.; Freitas, Helena; Luo, YongmingApplication of hyperaccumulator-endophyte symbiotic systems is a potential approach to improve phytoremediation efficiency, since some beneficial endophytic bacteria are able to detoxify heavy metals, alter metal solubility in soil, and facilitate plant growth. The objective of this study was to isolate multi-metal resistant and plant beneficial endophytic bacteria and to evaluate their role in enhancing plant growth and metal accumulation/translocation. The metal resistant endophytic bacterial strain E6S was isolated from stems of the Zn/Cd hyperaccumulator plant Sedum plumbizincicola growing in metalliferous mine soils using Dworkin and Foster salts minimal agar medium with 1-aminocyclopropane-1-carboxylate (ACC) as the sole nitrogen source, and identified as homologous to Achromobacter piechaudii based on morphological and biochemical characteristics, partial 16S rDNA sequence and phylogenetic analysis. Strain E6S showed high level of resistance to various metals (Cd, Zn, and Pb). Besides utilizing ACC, strain E6S exhibited plant beneficial traits, such as solubilization of phosphate and production of indole-3-acetic acid. Inoculation with E6S significantly increased the bioavailability of Cd, Zn, and Pb in soil. In addition, bacterial cells bound considerable amounts of metal ions in the following order: Zn > Cd >Pb. Inoculation of E6S significantly stimulated plant biomass, uptake and bioaccumulation of Cd, Zn, and Pb. However, E6S greatly reduced the root to shoot translocation of Cd and Zn, indicating that bacterial inoculation assisted the host plant to uptake and store heavy metals in its root system. Inoculation with the endophytic bacterium E6S homologous to A. piechaudii can improve phytostabilization of metalliferous soils due to its effective ability to enhance in situ metal rhizoaccumulation in plants.
- Biochemical and Molecular Mechanisms of Plant-Microbe-Metal Interactions: Relevance for PhytoremediationPublication . Ma, Ying; Oliveira, Rui S.; Freitas, Helena; Zhang, ChangPlants and microbes coexist or compete for survival and their cohesive interactions play a vital role in adapting to metalliferous environments, and can thus be explored to improve microbe-assisted phytoremediation. Plant root exudates are useful nutrient and energy sources for soil microorganisms, with whom they establish intricate communication systems. Some beneficial bacteria and fungi, acting as plant growth promoting microorganisms (PGPMs), may alleviate metal phytotoxicity and stimulate plant growth indirectly via the induction of defense mechanisms against phytopathogens, and/or directly through the solubilization of mineral nutrients (nitrogen, phosphate, potassium, iron, etc.), production of plant growth promoting substances (e.g., phytohormones), and secretion of specific enzymes (e.g., 1-aminocyclopropane-1-carboxylate deaminase). PGPM can also change metal bioavailability in soil through various mechanisms such as acidification, precipitation, chelation, complexation, and redox reactions. This review presents the recent advances and applications made hitherto in understanding the biochemical and molecular mechanisms of plant-microbe interactions and their role in the major processes involved in phytoremediation, such as heavy metal detoxification, mobilization, immobilization, transformation, transport, and distribution.
- Biodegradation of mono-, di- and trifluoroacetate by microbial cultures with different originsPublication . Alexandrino, Diogo A.M.; Ribeiro, Inês; Pinto, Luís M.; Cambra, Rafael; Oliveira, Rui S.; Pereira, Filipe; Carvalho, Maria F.This work focused on the biodegradation of three structurally related fluoroacetates (FAs), mono- (MFA), di- (DFA) and trifluoroacetate (TFA), using as microbial inocula samples collected from a site with a long history of industrial contamination and activated sludge obtained from a municipal wastewater treatment plant. Biodegradation experiments were carried out under different modes of substrate supplementation, which included (i) FAs fed as sole carbon sources; (ii) FAs (only for DFA and TFA) fed in co-metabolism with sodium acetate; and (iii) mixtures of MFA with DFA or TFA. Biodegradation of the target compounds was assessed through fluoride ion release. Defluorination was obtained in the cultures fed with MFA, while DFA and TFA were recalcitrant in all tested conditions. When present in mixture, DFA was shown to inhibit biodegradation of MFA, while TFA had no effect. A total of 13 bacterial isolates obtained from MFA degrading cultures were found to degrade 20mgL-1 of this compound, as single strains, when supplemented as a sole carbon source. Sequencing of the 16S rRNA gene indicated that among these degrading bacteria only Delftia acidovorans had been previously reported to be able to degrade MFA. This work shows that, despite their similar chemical structures, biodegradation of the three tested FAs is very distinct and draws attention to the unknown impacts that the accumulation of DFA and TFA may have in the environment as a result of their high recalcitrance.