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  • Bioactive extracts from Salicornia ramosissima J. woods biorefinery as a source of ingredients for high-value industries
    Publication . Hulkko, Laura Sini Sofia; Rocha, Rui Miranda; Trentin, Riccardo; Fredsgaard, Malthe; Chaturvedi, Tanmay; L, Custódio; Thomsen, Mette Hedegaard
    Salt-tolerant plants, also known as halophytes, could provide a novel source of feedstock for biorefineries. After harvesting fresh shoots for food, the lignified fraction of Salicornia ramosissima J. Woods could be used to produce bioactive botanical extracts for high-value industries such as nutraceuticals, cosmetics, and biopharmaceuticals. The residual fraction after extraction can be further used for bioenergy or lignocellulose-derived platform chemicals. This work analysed S. ramosissima from different sources and growth stages. After pre-processing and extractions, the obtained fractions were analysed for their contents of fatty acids, pigments, and total phenolics. Extracts were also evaluated for their in vitro antioxidant properties and inhibitory effect towards enzymes related to diabetes, hyperpigmentation, obesity, and neurogenerative diseases. The ethanol extract from the fibre residue and the water extract from completely lignified plants showed the highest concentration of phenolic compounds along with the highest antioxidant potential and enzyme-inhibitory properties. Hence, they should be further explored in the context of biorefinery.
    2023-03-09Journal article Open access Show more
  • Entomopathogenic fungi from Algarve region (Portugal): studies on their natural occurrence in the soil and multitrophic interactions that shape their biocontrol potential
    Publication . Bueno Pallero, Francisco Ángel; Neto, Luís Mascarenhas; Dionísio, Lídia Pó Catalão; Herrera, Raquel Campos
    The entomopathogenic fungi (EPF) are well-known beneficial soil organisms naturally occurring in the soil. Learning about their natural distribution in representative habitats and their interactions with other soil organisms can establish the best ecological scenario for the activity as biocontrol agents. Also, the co-formulation of two entomopathogens with plant-based products can be an affordable approach for farmers. With the Algarve region (Portugal) as a research frame, the objectives of this PhD thesis were: (1) to investigate the natural distribution of EPF in soils from the Algarve in four habitats (oak, pines, palmettoes, and citrus groves) and two soil eco-regions (calcareous and noncalcareous), (2) to evaluate whether the presence of entomopathogenic nematodes (EPN) or/and nematophagous fungi (NF) can affect the biocontrol potential of EPF, and (3) to investigate the impact of plant-based oil adjuvants on biocontrol activity of single or combined EPF and EPN, and the impact of time and temperature in the EPN survival and activity. Firstly, we combined three isolation methods (fresh soil, dry soil, and selective media) to investigate the natural EPF distribution in the Algarve, using traditional and molecular tools for the identification. We established the assemblage of the EPF with the soil properties and EPN by using multivariate analysis. Second, we investigated the multitrophic interactions in single (EPF, EPN, NF), dual (EPN+EPF, EPF+NF, EPN+NF) and triple (EPN+EPF+NF) combinations of one EPF (Beauveria bassiana), one EPN (Steinernema feltiae), and two NF (Arthrobotrys musiformis and Purpureocillium lilacinum). Three different fungal applications (contact with mycelia, immersion, and injection) simulated different timing of fungal arrival. Also, we evaluated the interaction in the mycelia growth between EPF and NF species. We tested the impact on biocontrol of two plant-based oils (coconut and olive oils) when combined the EPF B. bassiana and the EPN Steinernema colombiense. Also, the viability and virulence of EPN incubated at five temperatures (4, 8, 14, 20, and 24°C) and five incubation times (1, 3, 7, 14, and 21 days) with both plant-based adjuvants was also evaluated. The distribution of EPF in the Algarve region was not driven by botanical group or by ecoregion (calcareous versus non-calcareous). Five EPF species were identified, with B. bassiana as the dominant EPF (34% of the localities), followed by Fusarium solani (26%), and F. oxysporum (14%), both reported as EPF for the first time in Portugal. The species P. lilacinus (8%) and Metarhizium anisopliae (2%) were minority. Soil pH, organic matter, and Mg content explained most of the variability of the EPF community and EPN species-specific distribution. Second, we observed that EPF B. bassiana limited both NF species growth and viceversa. The EPF B. bassiana dominated triple-interaction when mycelia were exposed. The EPN S. feltiae dominated the triple-interaction in immersion exposure. The NF A. musiformis caused larval mortality if vectored inside the host. Finally, the plant-based oils tested wer compatible with the EPF and EPN. The combination of EPN+EPF produced an additive effect. EPN survival was higher in coconut than olive oil and water mixtures up to 7 days at 4ºC. Moreover, olive oil supported higher larval mortality caused by EPN than coconut oil at 4-20ºC and 14 days. Overall, this thesis provides new insights on the interactions occuring in the soil that can modulate their activity of EPF as biological control agents.
    2023-03-09Doctoral thesis Open access Show more