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- Unveiling Lichen’s Hidden Arsenal against multidrug resistance: A Systematic Review of their essential oils, volatile compounds and extracts with antimicrobial applicationsPublication . Essadki, Yasser; El Amrani Zerrifi, Soukaina; Carvalho, Maria de Fátima; Barros, Lillian; Vasconcelos, Vitor; Campos, Alexandre; El Khalloufi, Fatima; Oudra, Brahim; Martins, Rosário; Martins, RosarioThe increase in multidrug resistance in microorganisms and the rise of emergent infectious diseases worldwide is a threat to human and animal health. Therefore, research on new molecules with antibiotic potential is a priority. Lichens have a unique secondary metabolism with relatively untapped potential, yet their essential oils (EOs) and volatile organic compounds (VOCs) remain a relatively untapped resource. This systematic review was conducted following PRISMA 2020 guidelines, with a comprehensive search performed in the Web of Science database for studies published up to 2023. From 254 identified records, six studies involving nine lichen species (Evernia prunastri, Evernia divaricata, Cladonia rangiformis, Cladonia furcata, Parmotrema perlatum, Lichina pygmaea, Parmelia perlata, Hypogymnia physodes, and Parmelia sulcata) met the eligibility criteria. The synthesized data show that these volatile fractions possess significant antimicrobial potential, with minimum inhibitory concentrations (MICs) generally lower than 1 mg/mL. Major bioactive constituents identified include atraric acid, orsellinates, and various sesquiterpenes. While the current evidence highlights a strong potential of lichen volatiles against pathogens, research is limited to a small fraction of known species. This review identifies a critical gap in testing these compounds directly against MDR clinical isolates and suggests that future research should focus on high-biomass species and the heterologous expression of lichen biosynthetic genes to develop sustainable antimicrobial applications.
- Pigments profile and antioxidant potential of extremophile cyanobacteria isolated from the Mexican Volcanic Lake ChichonalPublication . Silva, Raquel; Gonçalves, Talita; Morone, Janaína; Moreira, Gabriela Alves; Morais, João; Hentschke, Guilherme Scotta; Alvarez-Gutierrez, Peggy Elizabeth; Batista-García, Ramon Alberto; Vasconcelos, Vitor; Lopes, GracilianaCyanobacteria are ancient and prolific microorganisms for which the current knowledge remains limited. The present work constitutes the first report on the presence of the cyanobacteria Tolypothrix sp. LEGE 221228, Nostoc sp. LEGE 221229, Scytonema sp. LEGE 221230 and Drouetiella sp. LEGE 221231 in the volcanic crater lake in Chichonal (Chiapas-Mexico), and in the characterization of their pigments profile and antioxidant potential, through the application of biorefinery approaches. The identification of cyanobacteria species was achieved through advanced morphology-based methods for cyanobacterial taxonomy. The HPLC-PDA analysis of the cyanobacteria acetone extracts revealed β-carotene, echinenone and chlorophyll-a as the main pigments. Drouetiella sp. LEGE 221231 presented the highest β-carotene concentration (63.67 μg/mL), total carotenoids (87.92 μg/mL) and chlorophylls (20.88 μg/mL), closely followed by Tolypothrix sp. LEGE 221228 (with 51.37, 75.14 and 14.88 μg/mL, respectively), this being the first report on the carotenoid and chlorophylls profile of these strains. Aqueous extracts revealed the highest content of phycoerythrin in Tolypothrix sp. LEGE 221228 (50.61 mg/g) and of phycocyanin in Nostoc sp. LEGE 221229 (57.66 mg/g), standing out in superoxide anion radical scavenging, while the acetonic ones were more effective in scavenging nitric oxide radical. For both, Tolypothrix sp. LEGE 221228 was the most effective, presenting the lowest IC50 (53.75 and 57.68 μg/mL, respectively). Overall, the present study enriches the knowledge on biodiversity of cyanobacteria from underexplored environments, enhancing their potential biotechnological applications as producers of added value secondary metabolites with interest in food, pharmaceutical and cosmetic industries.
- Bibliometric analysis towards industrial-scale use of Marine Algae and Lichens as soil amendments and plant biofertilizers for sustainable agriculturePublication . Ouala, Oumaima; Essadki, Yasser; Oudra, Brahim; Khalloufi, Fatima El; Martins, Rosário; Martins, RosarioThe nutrient-rich composition of seaweeds and lichens makes them well-suited for agricultural applications. Their use as alternatives to synthetic fertilizers contributes to sustainable agricultural production, enabling farmers to adopt ecological practices while maintaining or increasing crop productivity. This review aims to highlight the status and trends of research, along with a literature analysis on the application of these biomasses in sustainable agriculture. A bibliometric analysis was performed based on two databases (Scopus and Web of Science) to overview the main research topics regarding the use of biomasses studied in agriculture, thus providing useful information for future research. The biochemical composition and agricultural applications of these biomasses have been highlighted. The analysis shows that these biomasses are rich of nutrient compounds, revealing their roles and mechanisms of action on the chemical, nutritional properties, and soil microbial activities and their effect on plant growth, using various extraction and application methods. It also highlighted the potential of seaweeds for protection against biotic and abiotic stresses. In light of all the data presented in this review, it is possible to stimulate farmers’ interest in using seaweeds and lichens as natural fertilizers, with a focus on sustainable and ecological agriculture mainly in developing countries.
- Colouring applications of microalgae and cyanobacteria photosynthetic pigments: Challenges for industrial and market acceptancePublication . Reimão, Mariana; Almeida, Liliana; Ramos, Cristiana; Eusébio, Nádia; Martins, Rosário; Silva, Manuela Vieira da; Vasconcelos, Vítor; Freitas, Marisa; Freitas, Marisa; Vieira da Silva, Manuela; Martins, Rosario; REIMÃO BORGES LOPES DA SILVA, MARIANAMicroalgae and cyanobacterial photosynthetic pigments possess immense potential for sustainable colouring applications in industries such as food, feed, cosmetics and textiles, primarily because of their vibrant colours, safety and eco-friendliness. These photosynthetic pigments align with the growing demand for eco-conscious products. However, substantial challenges persist at the industrial level, particularly in scaling up production and achieving acceptance in niche markets. This review highlights the critical roles of abiotic factors such as light quality, temperature, pH, nutrient availability and salinity in enhancing pigment production using conventional production methods. Additionally, issues related to the cost, purity and stability of the pigments must be addressed to facilitate broader acceptance. Looking forward, the focus must be on developing innovative cultivation techniques that optimise and define the abiotic conditions most favourable for maximum pigment production or even incorporate genetic engineering tools. Additionally, exploring untapped species from inhospitable environmental sources and integrating the residual biomass through biorefinery processes represent effective approaches for enhancing the sustainability of microalgae and cyanobacterial pigment production on an industrial scale. Overcoming these barriers utilising targeted research and industry collaboration as well as fostering market acceptance is essential for fully harnessing the potential of these natural pigments and driving the transition towards more sustainable industrial colouring practices.
- Toxic and non-toxic cyanobacterial biomass as a resource for sustainable agriculture: A lettuce cultivation experimentPublication . Massa, Anabella; Santos, Érica; Martins, Diogo; Azevedo, Joana; Reimão, Mariana; Almeida, Agostinho; Azevedo, Rui; Pinto, Edgar; Vasconcelos, Vítor; Campos, Alexandre; Freitas, MarisaCyanobacteria represent a promising resource for sustainable agriculture, as they have demonstrated the ability to restore soil fertility even after death and decay. However, several cyanobacteria can also release secondary metabolites, such as cyanotoxins, which may compromise the quality of agricultural products and pose a potential risk to human health. Depending on the concentration of exposure, few studies reported deleterious effects on plant species when irrigated with cylindrospermopsin (CYN) contaminated water, impairing plant growth and leading to food product contamination, while other studies show promoting effects on plant yield. To evaluate the potential of cyanobacterial biomass (cyanotoxin-containing or not) as a sustainable resource for soil amendment, biostimulants or fertilizers for lettuce cultivation, a study was carried out that consisted of the culture of lettuce plants under controlled conditions, in soil: (1) with no extra nutrient addition (control) and supplemented with 0.6 g of freeze-dried Raphidiopsis raciborskii biomass of (2) a non-CYN-producing strain, (3) a CYN-producing strain, and (4) the same CYN-producing strain pasteurized. Results showed no significant differences in photosystem II efficiency with the amendment addition. On the contrary, shoot fresh weight significantly increased in lettuce plants grown with the cyanobacterial biomass addition, especially in condition (3). In addition, there were significant differences in mineral concentrations in lettuce leaves after the cyanobacterial biomass addition, such as K, Na, Ca, P, Mg, Mn, Zn, Cu, Mo, and Co. CYN accumulation was detected under conditions (3) and (4), with concentrations observed in descending order from roots > soil > shoot. Nevertheless, the CYN concentration in edible tissues did not exceed the WHO-proposed tolerable daily intake of 0.03 μg/kg/day. These findings suggest that incorporating cyanobacterial biomass as a soil amendment, biostimulant or fertilizer for lettuce cultivation, even with trace amounts of CYN (1–40 μg/g), may enhance plant yield without leading to cyanotoxin accumulation in edible tissues above the WHO-recommended tolerable daily intake.
- Application of real-time PCR in the assessment of the toxic cyanobacterium cylindrospermopsis raciborskii abundance and toxicological potentialPublication . Moreira, Cristiana; Martins, António; Azevedo, Joana; Freitas, Marisa; Regueiras, Ana; Vale, Micaela; Antunes, Agostinho; Vasconcelos, VítorCyanobacteria are prokaryotic photosynthetic microorganisms that pose a serious threat to aquatic environments because they are able to form blooms under eutrophic conditions and produce toxins. Cylindrospermopsis raciborskii is a planktonic heterocystous filamentous cyanobacterium initially assigned to the tropics but currently being found in more temperate regions such as Portugal, the southernmost record for this species in Europe. Cylindrospermopsin originally isolated from C. raciborskii is a cytotoxic alkaloid that affects the liver, kidney, and other organs. It has a great environmental impact associated with cattle mortality and human morbidity. Aiming in monitoring this cyanobacterium and its related toxin, a shallow pond located in the littoral center of Portugal, Vela Lake, used for agriculture and recreational purposes was monitored for a 2-year period. To accomplish this, we used the real-time PCR methodology in field samples to quantify the variation of specific genetic markers with primers previously described characterizing total cyanobacteria (16S rRNA), C. raciborskii (rpoC1), and cylindrospermopsin synthetase gene (pks). The results report the high abundance of both cyanobacteria and C. raciborskii in Vela Lake, with C. raciborskii representing 0.4% to 58% of the total cyanobacteria population. Cylindrospermopsin synthetase gene was detected in one of the samples. We believe that with the approach developed in this study, it will be possible to monitor C. raciborskii population dynamics and seasonal variation, as well as the potential toxin production in other aquatic environments.
- Environmentally friendly and cost-effective approaches to reduce toxin content in toxic cyanobacterial biomassesPublication . Loss, Letícia; Azevedo, Joana; Azevedo, Tomé; Freitas, Marisa; Vasconcelos, Vítor; Campos, AlexandreCyanobacterial outgrowths are naturally occurring processes in eutrophic aquatic ecosystems. Furthermore, as a result of climate change and anthropogenic pollution, cyanobacteria harmful algal blooms (CyanoHABs) are expanding worldwide. CyanoHABs are considered a threat to human health and environment due to the production of potent toxic substances, but at the same time, valuable products can be obtained from these microorganisms. The main objective of this study was to test straightforward and cost-effective methods to reduce the toxin content of cyanobacterial biomass for the exploitation of this important biological resource. To carry out this study, lyophilized or hydrated biomass from microcystin-LR (MC-LR) producing Microcystis aeruginosa and cylindrospermopsin (CYN) producing Chrysosporum ovalisporum strains were subjected to the following treatments: (1) thermal (50 °C); (2) ultraviolet (UV) radiation; (3) ozone; and (4) sunlight, for periods varying between 2 and 12 h. MC-LR and CYN concentrations were quantified by LC-MS and compared between experimental groups. The results show a significant reduction in the amount of MC-LR in M. aeruginosa biomass (lyophilized and hydrated) exposed to sunlight. Since no other treatment reduced MC-LR in M. aeruginosa biomass, this molecule was demonstrated to be very stable. Regarding CYN, the concentration of this toxin in C. ovalisporum biomass was significantly reduced with the exposure to UV radiation, to approximately 51% of the initial concentration after 2 h of exposure; 86% reduction after 5 h of exposure; and 77% reduction after 12 h of exposure. Overall, this study demonstrates that the toxicity of cyanobacterial biomass can be reduced by employing environmentally friendly and cost-effective treatments with sunlight and UV radiation.
- In vitro antimicrobial activity of volatile compounds from the Lichen Pseudevernia furfuracea (L.) Zopf. against multidrug-resistant bacteria and fish pathogensPublication . Essadki, Yasser; Hilmi, Adel; Cascajosa-Lira, Antonio; Girão, Mariana; Darrag, El Mehdi; Rosário Martins, Maria; Romane, Abderrahmane; Zerrifi, Soukaina El Amrani; Mugani, Richard; Tazart, Zakaria; Redouane, El Mahdi; Jos, Angeles; Cameán, Ana M.; Vasconcelos, Vitor; Campos, Alexandre; Khalloufi, Fatima El; Oudra, Brahim; Barakate, Mustapha; Carvalho, Maria de FátimaLichens are symbiotic organisms with unique secondary metabolism. Various metabolites from lichens have shown antimicrobial activity. Nevertheless, very few studies have investigated the antimicrobial potential of the volatile compounds they produce. This study investigates the chemical composition and antimicrobial properties of volatile compounds from Pseudevernia furfuracea collected in two regions of Morocco. Hydrodistillation was used to obtain volatile compounds from samples collected in the High Atlas and Middle Atlas. Gas chromatography–mass spectrometry (GC-MS) analysis identified phenolic cyclic compounds as the primary constituents, with atraric acid and chloroatranol being the most abundant. Additionally, eight compounds were detected in lichens for the first time. The antimicrobial activity of these compounds was assessed using disc diffusion and broth microdilution methods. Both samples demonstrated significant antimicrobial effects against multidrug-resistant human bacteria, reference microorganisms, fish pathogens, and Candida albicans, with minimum inhibitory concentrations (MICs) ranging from 1000 µg/mL to 31.25 µg/mL. This study provides the first report on the volatile compounds from Pseudevernia furfuracea and their antimicrobial effects, particularly against fish pathogens, suggesting their potential as novel antimicrobial agents for human and veterinary use. Further research is warranted to explore these findings in more detail.
- The neuroprotective role of cyanobacteria with focus on the anti-inflammatory and antioxidant potential: Current status and perspectivesPublication . Rodrigues, Flávia; Reis, Mariana; Ferreira, Leonor; Grosso, Clara; Ferraz, Ricardo; Vieira, Mónica; Vasconcelos, Vítor; Martins, RosárioNeurodegenerative diseases are linked to the process of neurodegeneration. This can be caused by several mechanisms, including inflammation and accumulation of reactive oxygen species. Despite their high incidence, there is still no effective treatment or cure for these diseases. Cyanobacteria have been seen as a possible source for new compounds with anti-inflammatory and antioxidant potential, such as polysaccharides (sacran), phycobiliproteins (phycocyanin) and lipopeptides (honaucins and malyngamides), which can be interesting to combat neurodegeneration. As a promising case of success, Arthrospira (formerly Spirulina) has revealed a high potential for preventing neurodegeneration. Additionally, advantageous culture conditions and sustainable production of cyanobacteria, which are allied to the development of genetic, metabolic, and biochemical engineering, are promising. The aim of this review is to compile and highlight research on the anti-inflammatory and antioxidant potential of cyanobacteria with focus on the application as neuroprotective agents. Also, a major goal is to address essential features that brand cyanobacteria as an ecoefficient and economically viable option, linking health to sustainability.
- Carotenoids from cyanobacteria modulate iNOS and inhibit the production of inflammatory mediators: Promising agents for the treatment of inflammatory conditionsPublication . Morone, Janaína; Vasconcelos, Vitor; Hentschke, Guilherme; Rosário Martins, Maria; Pinto, Eugénia; Lopes, GracilianaCyanobacteria are green multiproduct refineries of increasing interest for different industrial prospects. In this work, eleven cyanobacteria strains isolated from the Cape Verde archipelago were explored for their biotechnological applications in the field of inflammation. A biorefinery approach was employed to produce carotenoidtargeted extracts, further profiled by HPLC-PDA and explored for their ability to i) scavenge important physiological free radicals of oxygen (superoxide anion radical, O 2 •) and nitrogen (nitric oxide, • NO) involved in the inflammatory process ii) slow-down post-inflammatory hyperpigmentation and iii) modulate the activity of inf lammatory cytokine-producing enzymes, in enzymatic and cell systems comprising RAW 264.7 cells. The studied strains turned out to be important carotenoid producers (70.47–186.71 μ g mg 1 dry extract), mainly represented by β-carotene and zeaxanthin. The targeted-extracts stood-out for their potential to slow-down the inflammatory process through a multitarget approach: scavenging • NOandO 2 •, reducing inflammatory cytokines production through lipoxygenase inhibition, and modulating the inducible nitric oxide synthase in LPSstimulated RAW 264.7 cells, with strains of the order Nodosilineales revealing to be worth of further biotechnological exploitation.