Browsing by Author "Marques, A. P. G. C."
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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 energetic production from phytoremediation derived biomassPublication . Marques, A. P. G. C.; Castro, P. M. L.; Caetano, N. S.
- Assessment of the energetic production potential from phytoremediation derived biomassPublication . Marques, A. P. G. C.; Castro, P. M. L.; Caetano, N. S.There are presently more than 3 million contaminated sites all over EU, according to the EEA (report 25186 EN). Heavy metal (HM) contamination is of particular concern, as metals are not degradable and only transferable form one matrix to another [1]. Phytoremediation, a biologically based technology, is gaining attention from the public and is an attractive low cost alternative for soil requalification, by establishing a vegetation cover which will stabilize the site, avoiding dispersion of contamination and simultaneously removing pollutants present in the brownfield [1]. Although the fate of harvested biomass is a common obstacle for its implementation, it may represent an opportunity for producing energy. However, and although it has been proposed theoretically as an excellent option, the information available in literature concerning practical applications is scarce, despite the considerable degree of success reported [2,3,4]. The use of biomass grown in degraded and abandoned soils, not involving agricultural soils for energy crop cultivation, may increase the sustainability of utilizing biomass for energy generation, while it may allow for increasing the available agricultural soil through the consequent gradual decontamination of such brownfields. This work presents a novel integrated strategy comprising the utilization of all plant parts (maize and sunflower) parts for the generation of several energy products. Combinations of the selected energetic plants and plant growth promoting microbiota was assessed, and the soil and plant status was monitored to further understand the effects on crop productivity and soil remediation. At this stage harvested plant tissues were used for oil extraction and bioethanol production. The quality of the generated products was assessed and is discussed in this work to understand the effect of the HM soil contamination in the quality of the final products.
- 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.