Browsing by Author "Pereira, S. I. A."
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- Are PGPR’s traits and the inoculum size relevant for inoculation purposes in mine affected soils?Publication . Moreira, H.; Pereira, S. I. A.; Marques, A. P. G. C.; Rangel, A. O. S. S.; Castro, P. M. L.Cadmium and Zn concentrations in soil were largely increased in past decades due to several anthropogenic activities, including mining activities. Phytotechnologies can minimize their hazardous effects through the use of plants coupled with plant growth promoting rhizobacteria (PGPR). Several factors can contribute to the failure of PGPR inoculation, such as bacteria selection and the inoculum size. This work selected five metal resistant PGPR and assessed their in vitro growth promoting traits and their ability to induce maize germination and seedlings growth under Zn and Cd increasing concentrations. Additionally, the effect of the inoculum size (10 and 20 mL) of these strains and their efficiency in promoting plants’ growth and metal accumulation was evaluated in energy maize sowed in a mine soil. Some bacteria only exhibited or enhanced PGP traits when exposed to metals. Strains ECP37 and EDP28 showed to be the most efficient in improving seedlings’ growth with increasing metal concentrations, followed by S3X. Likewise, when inoculated in energy maize grown in mine soil, these same strains outperformed the others by increasing shoot biomass and elongation, metal accumulation, and by decreasing it in roots. The most evident effect of doubling the inoculum size was the increase in Cd accumulation, which was of 17% and 31% in roots and shoots, respectively. Other effects included a slight reduction in shoots' biomass (13%) and a general decrease in P tissue content. The results obtained suggest the selection of PGPR prior to inoculation in target soils should be primarily based in seedling growth promotion under metal exposure. Additionally, the size of the inoculum applied in the soil rhizosphere appears to be important in remediation processes and should be taken into account when planning phytomanagement strategies, especially when the biomass of plants is an important demand.
- Assessment of plant growth promoting bacterial populations in the rhizosphere of metallophytes from the Kettara mine, MarrakechPublication . Benidire, L.; Pereira, S. I. A.; Castro, P. M. L.; Boularbah, A.Soil heavy metal contamination resulting from mining activities constitutes a major environmental problem worldwide. The spread of heavy metals is often facilitated by scarce vegetation cover, so there is an urgent need to improve plant survival and establishment in these metalliferous areas. This study is aimed at the isolation and analysis of the phylogenetic relationship of culturable bacteria from the rhizosphere of metallophyte plants growing in the Kettara mine, in Marrakech, in order to select plant growth-promoting rhizobacteria (PGPR), which could be used in assisted-phytoremediation. Bacterial isolates were grouped by random amplified polymorphic DNA analysis and identified by 16S rRNA gene sequencing. Strains were further characterized for the production of plant growth-promoting (PGP) substances, such as NH3, siderophores, indol-3-acetic acid (IAA), hydrogen cyanide, and extracellular enzymes, for ACC-deaminase activity, their capacity to solubilize phosphate, and for their tolerance to heavy metals and acidic pH. Rhizosphere soils were highly contaminated with Cu and Zn and presented low fertility. Phylogenetic analysis showed that the rhizobacteria were affiliated to three major groups: γ-Proteobacteria (48 %), β-Proteobacteria (17 %), and Bacilli (17 %). The most represented genera were Pseudomonas (38 %), Bacillus (10 %), Streptomyces (10 %), and Tetrathiobacter (10 %). Overall, rhizobacterial strains showed an ability to produce multiple, important PGP traits, which may be helpful when applied as plant growth promoter agents in contaminated soils. PGPR were also able to withstand high levels of metals (up to 2615.2 mg Zn l(-1), 953.29 mg Cu l(-1), and 1124.6 mg Cd l(-1)) and the order of metal toxicity was Cd > Cu > Zn. The rhizobacterial strains isolated in the present study have the potential to be used as efficient bioinoculants in phytoremediation strategies for the recovery of Kettara mine soils.
- Bacteria immobilisation on hydroxyapatite surface for heavy metals removalPublication . Piccirillo, C.; Pereira, S. I. A.; Marques, A. P. G. C.; Pullar, R. C.; Tobaldi, D. M.; Pintado, M. E.; Castro, P. M. L.Selected bacterial strains were immobilised on the surface of hydroxyapatite (Ca-10(PO4)(6)(OH)(2) - HAp) of natural origin (fish bones). The capacity of the material, alone and in combination with the bacterial strains to act as heavy metal removers from aqueous streams was assessed. Pseudomonas fluorescens (S3X), Micro bacterium oxydans (EC29) and Cupriavidus sp. (1C2) were chosen based on their resistance to heavy metals and capacity of adsorbing the metals. These systems were tested using solutions of Zn(II), Cd(II) and in solutions containing both metals. A synergistic effect between the strains and HAp, which is effective in removing the target heavy metals on its own, was observed, as the combination of HAp with the bacterial strains led to higher adsorption capacity for both elements. For the solutions containing only one metal the synergistic effect was greater for higher metal concentrations; 1C2 and EC29 were the most effective strains for Zn(II) and Cd(II) respectively, while S3X was less effective. Overall, an almost four-fold increase was observed for the maximum adsorption capacity for Zn(II) when 10 was employed - 0.433 mmol/g in comparison of 0.121 mmol/g for the unmodified HAP. For Cd(II), on the other hand, an almost three-fold increase was registered with EC29 bacterial strain - 0.090 vs 0.036 mmol/g for the unmodified HAp. When the solutions containing both metals were tested, the effect was more marked for lower concentrations.
- Biodiversity associated to a floating wetland island in a freshwater pondPublication . Calheiros, C. S. C.; IIarri, M.; Godinho, M.; Castro, P. M. L.; Pereira, S. I. A.Floating wetland islands (FWI) are considered nature-based solutions that can be applied in different water bodies, such as lakes and rivers, in order to deliver a wide range of ecosystem services. They are recognized to promote local biodiversity, aesthetic integration and provide water quality enhancement through phytoremediation processes, although research is still needed to go deeper on the processes underlying the performance of these systems. The aim of this study was to assess de biodiversity associated to a FWI made of cork agglomerate, set up in 2018 in a freshwater pond. A polyculture comprising the plant species Iris germanica, Acorus gramineus, Caltha palustris, and Typha latifolia was considered. The culturable bacterial communities associated to the floating platform biofilm and to the plant rhizosphere were analyzed. The bacterial isolates were identified by 16S rRNA and characterized for their ability to produce plant growth promoting substances (e.g., indole-acetic acid, siderophores). The diversity of macroinvertebrates associated to FWI was also assessed. Water analysis of the pond were conducted. Preliminary data shows that there is a high bacterial diversity associated to this system and the ability to produce plant growth promoting substances has been shown. The bacterial strains with outstanding growth promoting traits can be used in the future to support phytoremediation strategies or plant resilience to climate change abiotic stresses. Regarding the biodiversity of macroinvertebrates associated with FWI they were mainly from the order Odonata. The FWI attracted mainly individuals of the genus Coenagrion (represented more than 80% of the fauna). These systems had proven to be a hotspot of biodiversity supporting water management plans and landscape and aesthetics integration. This study gives new insights into broadening the FWI applications in freshwater or polluted water.
- Biodiversity associated to floating wetland islandsPublication . Calheiros, C. S. C.; Ilarri, M.; Pereira, S. I. A.Floating wetland islands (FWI) are nature-based solutions that can be applied in different water bodies, such lakes, ponds and rivers, considering a wide range of purposes. They have been considered for eutrophication abatement, wastewater treatment and ecosystem rehabilitation. They are of great value since their efficiency relies on bioremediation processes and are thus very versatile in terms of water depuration but also on biodiversity promotion. These systems comprise a floating platform, selected plants and an anchoring system. Depending on their configuration, they will attract and harbor different organisms such macrofauna and microorganisms, that will use the platform as shelter, habitat, stepping stone, nursery, food source among other benefits. The plant species are of particular interest since they are the living interface between the platform and the water body and they must be selected according to criteria that will enable their successful establishment having in consideration the biotic factors. The present paper intends to give an overview of the role of FWI towards their associated biodiversity and what has been identified in literature as the main groups that can be found and related to operational conditions. This approach can support future decisions concerning the FWI implementation conditions and components towards biodiversity enhancement.
- Biofertilizers: unraveling the in vivo potential of PGPB traitsPublication . Sousa, Ana S. S.; Epelde, Lur; Alves, Paulo Célio; Castro, P. L.; Pereira, S. I. A.
- Chitosan-hydroxyapatite composites made from sustainable sources: a morphology and antibacterial studyPublication . Scalera, F.; Pereira, S. I. A.; Bucciarelli, A.; Tobaldi, D. M.; Quarta, A.; Gervaso, F.; Castro, P. M. L.; Polini, A.; Piccirillo, C.Chitosan (Cs) and hydroxyapatite (HA) 3D scaffolds/composites were prepared with a sustainable process, as HA was obtained using CaCO3 derived from cork, a natural material used as a template agent. The HA@Cs composites were prepared with HA in situ formation in a Cs solution, with a dissolution-precipitation mechanism. Different reaction times were considered, with time of 72 h leading to the best materials (sample CsHA_72). X-ray Diffraction (XRD) analysis confirmed HA formation. The analysis of Cs unit cell parameters showed that, for the unmodified Cs, the cell had larger dimensions and a higher degree of distortion than previously reported in literature; HA incorporation in the CsHA_72 composite led to a further increase in the cell dimensions. The morphology of the scaffolds was studied with Scanning Electron Microscopy (SEM) and a high level of porosity was observed; a statistical comparison was performed between the unmodified Cs and CsHA_72 to determine the pore size, structure, and distribution. This analysis, the first of this kind for this type of composites, showed smaller and more circular pores for the CsHA_72 composite (average diameter of 70 μm vs. 88 μm for unmodified Cs). The overall level of porosity, however, did not change (>77%); likewise, the Young modulus was not affected by HA incorporation (about 11 kPa). Antibacterial tests, performed on Escherichia coli and Staphylococcus aureus, showed that HA presence did not significantly reduce the antimicrobial properties; the composites were particularly effective towards S. aureus, as a >90% the bacterial population reduction was observed for an incubation time of 2 h. HA@Cs also showed excellent biocompatibility and good cell proliferation. The properties of these 3D scaffolds make them suitable for application as biomaterials.
- Diversity of metallophytes and metal(loid)-tolerant bacterial strains in a portuguese mine for phytotechnologies purposesPublication . Sousa, A. S. S.; Pereira, S. I. A.; Moreira, H.; Cunha, J.; Vila-Viçosa, C.; Castro, P.M.L.Soil contamination with metal(loid)s due to anthropogenic activities, such as mining, is a worldwide issue that affects ecosystem functioning and human health. Efforts are currently made to restore these soils through sustainable and economically strategies. Phytotechnologies stand out as reliable and ecologically sound options, focusing on the use of plants and their associated microorganisms to reclaim contaminated lands and decrease pollutant linkages. These options can also provide economic revenues, integrating soil restoration into the circular economy concept. Mining areas host metallophytes, either excluders or (hyper)accumulators, and plant growth-promoting bacteria (PGPB), adapted to high concentrations of metal(loid)s, that can be used in phytoremediation strategies. The Borralha mine is a deactivated tungsten producer located in the northern Portugal, in which the ending of mineral extraction left several open-air tailings highly contaminated with metal(loid)s, such as Cu, Zn, Cd, As and Pb. This study aimed to assess the most abundant metallophytes and characterize the culturable bacterial community present in Borralha mine tailings for biotechnological purposes. Plant biodiversity was assessed over 1 year period, covering the different seasons. Based on plant taxonomy, a total of 14 plant species were identified, with some species (e.g., Agrostis capillaris, Cytisus striatus, Erica arborea, Pinus pinaster, Rubus ulmifolius, Salix caprea and Sedum arenarium) showing potential to be used in remediation strategies. For soil bacteria characterization, a composite soil sample was collected from vegetated and non-vegetated areas in the tailing zone. A total of 65 bacterial isolates were isolated and characterized genotypically and phenotypically (e.g. metal tolerance and plant growth promoting traits). Several bacterial strains showed potential to be used as bioinoculants in assisted- phytoremediation approaches
- Employment of phosphate solubilising bacteria on fish scales – turning food waste into an available phosphorus sourcePublication . Santana, C. A.; Piccirillo, C.; Pereira, S. I. A.; Pullard, R. C.; Lima, S. M.; Castro, P. M. L.The increased use of fertilisers is a well-known problem; linked to this, there is an always higher demand for phosphorus (P). Because of this, it is crucial to use P from all possible sources and, if necessary, turn it into a soluble form, available for plants/crops. In this paper we report the use of aerobic phosphate solubilising bacteria (PSB) on the scales of the tilapia (Coptodon rendalli) fish, a waste from the food industry; this is the first time that PSB were employed on fish scales to mediate the available P. The scales were calcined to 700 °C to obtain a nanoscale powdery material (more easily solubilised), made of hydroxyapatite, Ca10(PO4)6(OH)2, a calcium phosphate with very low solubility. Seventeen different PSB strains were tested for their ability to solubilise phosphate (commercial tricalcium phosphate - TCP) and hydroxyapatite from fish scale (FSHA). The best performing bacterial strain (Acidovorax oryzae ZS 1–7) led to a P solubilisation more than 60 times higher than the negative control – at 325 mg/L, almost 40% of the available P was solubilised – one of the highest increased efficiencies reported for PBS. Such solubilisation was linked to a decrease of the pH to more acidic values of about 4. The strain ZS 1–7 showed higher P solubilisation efficiency with fish-derived FSHA than with commercial TCP. This approach showed a promising strategy for the valorisation of residues of the fish industry, turning them into a source of P, to be used for sustainable agriculture.
- Enhancing water reuse at a local scale: a constructed wetland case studyPublication . Magalhães, J.; Dolbeth, M.; Arenas, F.; Pereira, S. I. A.; Tsiamis, G.; Ntougias, S.; Calheiros, C.What are Constructed Wetlands? Constructed wetlands (CW) are engineered systems that are inspired by and mimicking processes (physical, biological, and chemical) and functions that occur in natural wetlands. Comprised of several components, impermeabilization liners and substrate, and as the key elements the plants and their associated microorganisms. They were thought primarily for wastewater treatment but nowadays are considered nature-based solution (NBS) of excellence in terms of flexibility of their application and services provided (Calheiros et al, 2020). Framework: CIRQUA is a project aiming to improve NBS, focusing on CW for wastewater treatment and water recovery in rural areas (Figure 1). CIRQUA will enhance CW efficiency by leveraging technological advancements, including innovative nanostructured filters, photocatalytic modules, advanced sensors and automated operational systems. The upgrade will also incorporate precision irrigation principles and integrate advanced artificial intelligence tools for optimizing performance (Figure 2). These innovations will aid in improving effluent quality, allowing the treated water and CW biomass to be used for irrigation and fertilization purposes, respectively, thus promoting circular economy at local scale. CIRQUA will also support, by using a zero-waste process, the circular bioeconomy by which biomass is expected to play a relevant role in meeting the global climate targets. Case study: A case study is being conducted in Portugal through by upgrading of an existent horizontal subsurface flow CW of ca 40 m². This CW was implemented in 2010 at Paço de Calheiros, a tourism house surrounded by a farm, located in Calheiros, North of Portugal in a rural area dominated by agriculture and forests (Calheiros et al, 2015) (Figure 3). The CW was designed to act as secondary biological treatment, being placed after a previously installed septic tank. It functions in a continuous mode with no energy requirements. It is a system planted with a polyculture of a) Agapanthus africanus b) Canna flaccida c) Zantedeschia aethiopica d) Canna indica and e) Watsonia borbonica. The substrate material used in the CW was expanded clay Leca®M with a particle size ranging from 4 to 12.5 mm SaintGobain Weber Portugal, SA.