Repository logo
 
Loading...
Profile Picture

Search Results

Now showing 1 - 10 of 10
  • A review of common parameters and descriptors used in studies of the impacts of heavy metal pollution on marine macroalgae: identification of knowledge gaps and future needs
    Publication . Costa, Giulia Burle; Koerich, Gabrielle; Ramos, Bruna de; Ramlov, Fernanda; Martínez-Crego, Begoña; Costa, Monya; Jesus, Dora; Santos, Rui; Horta Jr., Paulo A.
    This study presents a systematic review to assess the main similarities and gaps in efforts to evaluate the impacts of heavy metals on benthic marine seaweeds. A total of 91 studies were compiled, the main parameters (abiotic, biological, ecotoxicological, and heavy metals) and descriptors of which were evaluated by quantitative and qualitative analyses. Our results indicate the importance of diversifying searches by including different languages (i.e. English, Portuguese and Spanish). Most of the studies were field characterizations, with few abiotic parameters and/or seasonality evaluations being employed. In contrast, the assessment of ecotoxicological parameters was highly frequent, which seems incoherent considering the absence of data to support the use of these results in biomonitoring applications. The genera Sargassum, Ulva and Enteromorpha were widely studied worldwide, apart from a small fraction of studies assessing higher levels of biological organization. Moreover, the use of different parameters and descriptors by the evaluated studies precludes making conclusive or reliable comparisons. These findings highlight the importance of greater efforts to construct a concise baseline of knowledge using similar parameters so that global evaluations of the impacts of heavy metals on photosynthetic organisms can be undertaken.
  • Comparison of different pretreatment processes envisaging the potential use of food waste as microalgae substrate
    Publication . Marques, Fabiana; Pereira, Francisco; Machado, Luís; Martins, Joana T.; Pereira, Ricardo N.; Costa, Monya; Genisheva, Zlatina; Pereira, Hugo; Vicente, António A.; Teixeira, José A.; Geada, Pedro
    A significant fraction of the food produced worldwide is currently lost or wasted throughout the supply chain, squandering natural and economic resources. Food waste valorization will be an important necessity in the coming years. This work investigates the ability of food waste to serve as a viable nutritional substrate for the heterotrophic growth of Chlorella vulgaris. The impact of different pretreatments on the elemental composition and microbial contamination of seven retail food waste mixtures was evaluated. Among the pretreatment methods applied to the food waste formulations, autoclaving was able to eliminate all microbial contamination and increase the availability of reducing sugars by 30%. Ohmic heating was also able to eliminate most of the contaminations in the food wastes in shorter time periods than autoclave. However, it has reduced the availability of reducing sugars, making it less preferable for microalgae heterotrophic cultivation. The direct utilization of food waste containing essential nutrients from fruits, vegetables, dairy and bakery products, and meat on the heterotrophic growth of microalgae allowed a biomass concentration of 2.2 x 108 cells center dot mL-1, being the culture able to consume more than 42% of the reducing sugars present in the substrate, thus demonstrating the economic and environmental potential of these wastes.
  • Heatwave effects on the photosynthesis and antioxidant activity of the seagrass Cymodocea nodosa under contrasting light regimes
    Publication . Costa, Monya; Silva, João; Barrote, Isabel; Santos, Rui
    Global climate change, specifically the intensification of marine heatwaves, affect seagrasses. In the Ria Formosa, saturating light intensities may aggravate heatwave effects on seagrasses, particularly during low spring tides. However, the photophysiological and antioxidant responses of seagrasses to such extreme events are poorly known. Here, we evaluated the responses of Cymodocea nodosa exposed at 20 °C and 40 °C and 150 and 450 μmol quanta m−2 s−1. After four-days, we analyzed (a) photosynthetic responses to irradiance, maximum photochemical efficiency (Fv/Fm), the effective quantum yield of photosystem II (ɸPSII); (b) soluble sugars and starch; (c) photosynthetic pigments; (d) antioxidant responses (ascorbate peroxidase, APX; oxygen radical absorbance capacity, ORAC, and antioxidant capacity, TEAC); (d) oxidative damage (malondialdehyde, MDA). After four days at 40 °C, C. nodosa showed relevant changes in photosynthetic pigments, independent of light intensity. Increased TEAC and APX indicated an “investment” in the control of reactive oxygen species levels. Dark respiration and starch concentration increased, but soluble sugar concentrations were not affected, suggesting higher CO2 assimilation. Our results show that C. nodosa adjusts its photophysiological processes to successfully handle thermal stress, even under saturating light, and draws a promising perspective for C. nodosa resilience under climate change scenarios.
  • Heterotrophic and photoautotrophic media optimization using response surface methodology for the Novel Microalga Chlorococcum amblystomatis
    Publication . Correia, Nádia; Pereira, Hugo; Schulze, Peter S.C.; Costa, Monya; Santo, Gonçalo E.; Guerra, Inês; Trovão dos Santos, Mafalda; Barros, Ana; Cardoso, Helena; Silva, Joana L.; Gouveia, Luisa; Varela, João
    The nutritional requirements of novel microalgal strains are key for their effective cultivation and metabolite content. Therefore, the optimization of heterotrophic and photoautotrophic culture media is crucial for novel Chlorococcum amblystomatis growth. Heterotrophic and photoautotrophic biomass samples were characterized to identify the differences between their heterotrophic and photoautotrophic biomass composition and their biotechnological potential. Media optimization through surface response methodology led to 44.9 and 51.2% increments in C. amblystomatis-specific growth rates under heterotrophic and photoautotrophic growth, respectively. This microalga registered high protein content (61.49–73.45% dry weight), with the highest value being observed in the optimized photoautotrophic growth medium. The lipid fraction mainly constituted polyunsaturated fatty acids, ranging from 44.47 to 51.41% for total fatty acids (TFA) in cells under heterotrophy. However, these contents became significantly higher (70.46–72.82% TFA) in cultures cultivated under photoautotrophy. An interesting carotenoids content was achieved in the cultures grown in optimized photoautotrophic medium: 5.84 mg·g−1 β-carotene, 5.27 mg·g−1 lutein, 3.66 mg·g−1 neoxanthin, and 0.75 mg·g−1 violaxanthin. Therefore, C. amblystomatis demonstrated an interesting growth performance and nutritional profile for food supplements and feed products that might contribute to meeting the world’s nutritional demand.
  • Seagrass meadows improve inflowing water quality in aquaculture ponds
    Publication . de los Santos, Carmen B.; Olivé, Irene; Moreira, Márcio; Silva, André; Freitas, Cátia; Araújo Luna, Ravi; Quental-Ferreira, Hugo; Martins, Márcio; Costa, Monya; Silva, João; Cunha, Maria Emilia; Soares, Florbela; Pousão-Ferreira, Pedro; Santos, Rui
    Water quality is critical for fish health in aquaculture production. In flow-through systems, the inflowing water normally requires quality controls and treatments for being supplied from coastal water bodies that can be polluted by nutrients, suspended solids, and microorganisms. Here we assess how seagrass meadows benefit aquaculture systems through the provision of ecosystem services (water filtration, biological control, and regulation of dissolved gasses) in the water reservoir that supplies earthen ponds in an aquaculture system in southern Portugal. In the 1.45-ha reservoir, seagrasses retained daily an estimate of 0.8–1.8 kg d−1 of nitrogen, 0.04–0.07 kg d−1 of phosphorus in their biomass, and 0.7–1.1 kg dw d−1 of suspended total particulate matter, bringing benefits in terms of nutrient and particle removal from the water column. Diel and spatial variation in faecal coliforms levels (Escherichia coli) in the reservoir suggested that seagrasses, in combination with light exposure, may reduce the levels of this pathogen. Furthermore, the seagrass-dominated system oxygenated the water through photosynthesis at a faster rate than the respiratory oxygen consumption, maintaining the system above the aquaculture minimum oxygen. This study demonstrates that seagrasses can be used as a nature-based solution to overcome water quality challenges in flow-through aquaculture ponds.
  • Photoacclimation strategies in northeastern Atlantic seagrasses: Integrating responses across plant organizational levels
    Publication . Schubert, Nadine; Freitas, Cátia; Silva, André; Costa, Monya; Barrote, Isabel; Horta, Paulo A.; Rodrigues, Ana Cláudia; Santos, Rui; Silva, João
    Seagrasses live in highly variable light environments and adjust to these variations by expressing acclimatory responses at different plant organizational levels (meadow, shoot, leaf and chloroplast level). Yet, comparative studies, to identify species' strategies, and integration of the relative importance of photoacclimatory adjustments at different levels are still missing. The variation in photoacclimatory responses at the chloroplast and leaf level were studied along individual leaves of Cymodocea nodosa, Zostera marina and Z. noltei, including measurements of variable chlorophyll fluorescence, photosynthesis, photoprotective capacities, non-photochemical quenching and D1-protein repair, and assessments of variation in leaf anatomy and chloroplast distribution. Our results show that the slower-growing C. nodosa expressed rather limited physiological and biochemical adjustments in response to light availability, while both species of faster-growing Zostera showed high variability along the leaves. In contrast, the inverse pattern was found for leaf anatomical adjustments in response to light availability, which were more pronounced in C. nodosa. This integrative plant organizational level approach shows that seagrasses differ in their photoacclimatory strategies and that these are linked to the species' life history strategies, information that will be critical for predicting the responses of seagrasses to disturbances and to accordingly develop adequate management strategies.
  • Genomewide transcriptional reprogramming in the seagrass Cymodocea nodosa under experimental ocean acidification
    Publication . Ruocco, Miriam; Musacchia, Francesco; Olivé, Irene; Costa, Monya; Barrote, Isabel; Santos, Rui; Sanges, Remo; Procaccini, Gabriele; Silva, João
    Here, we report the first use of massive-scale RNA-sequencing to explore seagrass response to CO2-driven ocean acidification (OA). Large-scale gene expression changes in the seagrass Cymodocea nodosa occurred at CO2 levels projected by the end of the century. C. nodosa transcriptome was obtained using Illumina RNA-Seq technology and de novo assembly, and differential gene expression was explored in plants exposed to short-term high CO2/low pH conditions. At high pCO(2), there was a significant increased expression of transcripts associated with photosynthesis, including light reaction functions and CO2 fixation, and also to respiratory pathways, specifically for enzymes involved in glycolysis, in the tricarboxylic acid cycle and in the energy metabolism of the mitochondrial electron transport. The upregulation of respiratory metabolism is probably supported by the increased availability of photo-synthates and increased energy demand for biosynthesis and stress-related processes under elevated CO2 and low pH. The upregulation of several chaperones resembling heat stress-induced changes in gene expression highlighted the positive role these proteins play in tolerance to intracellular acid stress in seagrasses. OA further modifies C. nodosa secondary metabolism inducing the transcription of enzymes related to biosynthesis of carbon-based secondary compounds, in particular the synthesis of polyphenols and isoprenoid compounds that have a variety of biological functions including plant defence. By demonstrating which physiological processes are most sensitive to OA, this research provides a major advance in the understanding of seagrass metabolism in the context of altered seawater chemistry from global climate change.
  • Daily regulation of key metabolic pathways in two seagrasses under natural light conditions
    Publication . Ruocco, Miriam; Barrote, Isabel; Hofman, Jan Dirk; Pes, Katia; Costa, Monya; Procaccini, Gabriele; Silva, João; Dattolo, Emanuela
    The circadian clock is an endogenous time-keeping mechanism that enables organisms to adapt to external environmental cycles. It produces rhythms of plant metabolism and physiology, and interacts with signaling pathways controlling daily and seasonal environmental responses through gene expression regulation. Downstream metabolic outputs, such as photosynthesis and sugar metabolism, besides being affected by the clock, can also contribute to the circadian timing itself. In marine plants, studies of circadian rhythms are still way behind in respect to terrestrial species, which strongly limits the understanding of how they coordinate their physiology and energetic metabolism with environmental signals at sea. Here, we provided a first description of daily timing of key core clock components and clock output pathways in two seagrass species, Cymodocea nodosa and Zostera marina (order Alismatales), cooccurring at the same geographic location, thus exposed to identical natural variations in photoperiod. Large differences were observed between species in the daily timing of accumulation of transcripts related to key metabolic pathways, such as photosynthesis and sucrose synthesis/transport, highlighting the importance of intrinsic biological, and likely ecological attributes of the species in determining the periodicity of functions. The two species exhibited a differential sensitivity to light-to-dark and dark-to-light transition times and could adopt different growth timing based on a differential strategy of resource allocation and mobilization throughout the day, possibly coordinated by the circadian clock. This behavior could potentially derive from divergent evolutionary adaptations of the species to their bio-geographical range of distributions.
  • Oxyfluorfen: a novel metabolic inhibitor to select microalgal chlorophyll-deficient mutant strains for nutritional applications
    Publication . Trovão dos Santos, Mafalda; Cardoso, Lucas; Schüler, Lisa; Machado, Adriana; Santo, Gonçalo Espírito; Pedroso, Humberto; Reis, Ana; Barros, Ana; Correia, Nádia; Costa, Monya; Ferreira, Sara; Cardoso, Helena; Mateus, Marília; Silva, Joana; Pereira, Hugo; Freitas, Filomena; Varela, João
    Nowadays, there is an increasing demand for novel feedstocks and alternative protein sources to meet global needs. Because of their rich nutritional profiles and high protein contents, microalgae-based food products and supplements are being developed. Nonetheless, these products present organoleptic characteristics such as taste, smell and colour that are often considered unpleasant by human and animal consumers. To address this constraint, strain improvement approaches such as random mutagenesis have been used, which combined with the right selection strategy, lead to more appealing microalgal biomass. In this work, a novel selection strategy using oxyfluorfen, an inhibitor of the chlorophyll synthesis pathway, was applied for the first time to isolate chlorophyll-deficient strains of Scenedesmus rubescens and Chlorella vulgaris upon treatment with ethyl methanesulfonate (EMS). With this approach, one S. rubescens brownish (37Y01) mutant strain, as well as two C. vulgaris mutant strains, one yellow (31Y15) and one white (31W62), were obtained. S. rubescens 37Y01 displayed a reduced protein content of 19.1% dry weight (DW) compared to that of the wildtype, which presented a protein content of 25.0% DW. C. vulgaris wildtype and mutants exhibited higher protein contents, in the 42.844.3% DW range, compared to Scenedesmus rubescens (p < 0.05). The selective pressure of this inhibitor allowed the selection of S. rubescens and C. vulgaris mutants displaying 55% and 95% decrease in chlorophyll content, respectively. The reduced chlorophyll content greatly improves the sensory properties and consumer acceptance of established mutants, increasing the potential of both strains as feedstocks to develop novel food products.
  • Isolation and selection of protein-rich mutants of chlorella vulgaris by fluorescence-activated cell sorting with enhanced biostimulant activity to germinate garden cress seeds
    Publication . Trovão dos Santos, Mafalda; Schüler, Lisa; Pedroso, Humberto; Reis, Ana; Santo, Gonçalo Espírito; Barros, Ana; Correia, Nádia; Ribeiro, Joana; Bombo, Gabriel; Gama, Florinda; Viana, Catarina; Costa, Monya; Ferreira, Sara; Cardoso, Helena; Varela, João; Silva, Joana; Freitas, Filomena; Pereira, Hugo
    Microalgae are a promising feedstock with proven biostimulant activity that is enhanced by their biochemical components (e.g., amino acids and phytohormones), which turns them into an appealing feedstock to reduce the use of fertilisers in agriculture and improve crop productivity and resilience. Thus, this work aimed to isolate protein-rich microalgal mutants with increased biostimulant activity. Random mutagenesis was performed with Chlorella vulgaris, and a selection of protein-rich mutants were sorted through fluorescence-activated cell sorting (FACS), resulting in the isolation of 17 protein-rich mutant strains with protein contents 19-34% higher than that of the wildtype (WT). Furthermore, mutant F4 displayed a 38%, 22% and 62% higher biomass productivity, growth rate and chlorophyll content, respectively. This mutant was then scaled up to a 7 L benchtop reactor to produce biomass and evaluate the biostimulant potential of this novel strain towards garden cress seeds. Compared to water (control), the germination index and the relative total growth increased by 7% and 19%, respectively, after the application of 0.1 g L-1 of this bioproduct, which highlights its biostimulant potential.