ITQB:AEM-PhD Theses
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- Aspergillus fumigatus fascinating associations: from chemical stressors to endobacterial partnersPublication . Piontkivska, Daryna; Pereira, Cristina Silva"The prevalence and impact of invasive fungal infections, claiming over 1.5 million lives annually, have reached alarming levels. Among the critical fungal pathogens identified by the World Health Organization, Aspergillus fumigatus stands out for its role in invasive pulmonary aspergillosis, particularly dangerous for immunocompromised individuals. With escalating antifungal resistance complicating treatment, there's an urgent need for innovative clinical management strategies. Despite strides in understanding, the genetic and ecological distinctions separating pathogenic from non-pathogenic strains remain elusive, highlighting the nuanced nature of A. fumigatus virulence. Understanding the interplay between ecology, genetics, and involvement of secondary players in fungal virulence is crucial.(...)"
- Identification and characterization of bioactive secondary metabolites from the filamentous fungus NeurosporacrassaPublication . Sequeira, Patrícia S.; Pereira, Cristina Silva; Goldman, Gustavo Henrique"The need for novel natural products arises from the continuous emergence of new pathogens and (multi)drug-resistant strains of known pathogens, as well as from the limited efficacy of existing treatment options in clinical practice. Fungi are major sources of natural products deriving from their secondary metabolism. These group of diverse disparate small molecules of fungal origin are usually not essential for growth, yet, they confer an advantage in the ecological niche.(...)"
- Ionic liquids as a versatile tool to study antimicrobial strategies of and against filamentous fungiPublication . Rothkegel, Maika Clara; Pereira, Cristina Silva"Life threatening microbial infections caused by pathogenic bacteria or fungi are becoming an increasing concern for our society, due to the increasing appearance of antimicrobial (multi-)resistant strains and the lack of appropriate treatment options. In the case of fungal infections, Aspergillus spp. can lead to severe invasive infections with Aspergillus fumigatus being the main cause, especially in severely immunocompromised patients."
- Cutin as a key player in plant immunityPublication . Moreira, Carlos Jorge da Silva; Pereira, Cristina Silva"The cuticle is the outermost defensive barrier in land plants, onstituting a shield that protects against both biotic and abiotic stresses. It is comprised by a group of organic solvent soluble lipids that are commonly referred to as waxes and the plant polyester cutin. "
- Suberin biotech potential: from bactericidal nanoparticles to optical sensors.Publication . Rodrigues, Rúben Miguel Lopes; Pereira, Cristina Silva"With the increased exposure to antibiotics and the matching selective pressure that it imposes, bacteria naturally have evolved to develop resistance to several antibiotics and, in the worst cases, multi drug resistance. This seriously affects the treatment of bacterial infections and the problem worsens when considering that the development of new antibiotic molecules is increasingly difficult and costly. Consequently, alternative antibacterial substances are being increasingly sought out, where antimicrobial lipids are being pointed as a promising solution. Fatty acids and monoglycerides are natural substances that possess antimicrobial properties, capable of destabilizing cell membranes, while causing several direct and indirect inhibitory effects, such as impairment of nutrient uptake, generation of peroxidation and auto-oxidation degradation products or direct lysis of bacterial cells and inhibition of enzyme activity. More importantly, evolution of resistant phenotypes is increasingly difficult. "
- Belowground fungi are key sentinels in forest soils vulnerable to pentachlorophenol pollution: a mechanistic study in Quercus suber forestsPublication . Varela, Adélia; Pereira, Cristina Silva"Atmospheric release of persistent organic pollutants (POPs) constitutes a silent threat through chronic contamination of soils at global scale; yet fundamental understanding of their occurrence, sources and fate is still largely lacking. The above statement has inspired the working hypothesis of this doctoral thesis – active sources of pentachlorophenol (PCP) pollution are reaching the soils of emblematic cork oak forests (Chapter II and III), hence altering the functioning of the belowground mycobiota (Chapter III and IV) that act as buffer against the disturbance caused by the biocide (Chapter III and IV).(...)"
- Revealing specialisation events induced by pollutants in belowground fungal communitiesPublication . Martins, Celso Filipe Ferreira; Pereira, Cristina Silva"Chemical pollution has been in the centre of scientific discussion for decades, mainly due to toxicological motives. Pollution and climate change is leading to associated geological/geochemical and atmospheric alterations that negatively impact all ecosystems, including humans. To date our understanding of the environmental impact of pollution and climate change is still very limited. Among the ecological groups that are affected by pollution the “unseen “majority” are the microbial communities especially fungi, that dominate most habitats on Earth. Several studies exist focusing on the effects of organic pollutants towards microbes, especially considering their overall toxicity and degradation with emphasis on fungi due to their impressive catabolic capacities. However, how exposure to toxicants impacts the dynamics of microbial communities remains poorly understood.(...)"
- Triggering secondary metabolite biosynthesis: exploring the effects of ionic liquids in fungal metabolismPublication . Alves, Paula Cristina; Pereira, Cristina Silva; Becker, JörgFilamentous fungi are able to synthesise an array of small molecules (secondary metabolites), which are usually not essential for fungal growth but confer competitiveness. As a consequence, numerous secondary metabolites remain cryptic at the artificial conditions of cultivation in a research laboratory. Even in Aspergillus nidulans, one of the most well studied fungi, numerous metabolites remain unseen. Several strategies have been used to solve this knowledge gap, some of which require prior knowledge of genomic sequences, relying on manipulation of targeted genes encoding components of either secondary metabolism or regulatory pathways. Other approaches may be applied also in less well characterised strains, such as cultivation with other species/organisms or modification of the growth media composition. (...)
- Exploring ionic liquids′ unique stimuli to elucidate uncharacterised cellular and molecular mechanisms in filamentous fungiPublication . Hartmann, Diego de Oliveira; Pereira, Cristina Silva; Louro, RicardoThe emergence of new fungal pathogens, either of plants or animals, and the increasing number of reported cases of resistant human pathogenic strains to the available antifungal drugs reinforces the need for better understanding the biology of filamentous fungi. Conventional drugs target components of the fungal membrane or cell wall, therefore identifying novel intracellular targets, yet unique to fungi, is a global priority.(...)
- On the way towards the understanding of suberin degradation by Aspergillus nidulansPublication . Martins, Isabel Tavares Lima; Pereira, Cristina Silva; Rebelo, Luís PauloFilamentous fungi ensure major recyclability cycles on Earth. Two tons of plant material are deposited per year and per hectare (average in temperate zones), of which biopolyesters are the third most abundant of the major plant polymers. Suberin, a complex aromatic-aliphatic cross-linked biopolyester, is a structural component of the plant cell wall. It builds an inner barrier which is ingrained between a primary and a tertiary cell wall (i.e. between a lignocellulose layer and a polysaccharide one, respectively). The suberin barrier is virtually impermeable to water and solutes and protects the plant from numerous biotic and abiotic stresses. It is thought to physically strengthen the cell wall, protecting it from microbial hydrolysis, and to exhibit antimicrobial properties. Hence, biopolyester degradation by filamentous fungi (in particular by Ascomycota strains - preliminary demonstrated in few studies) should be further considered.(...)