Revealing fungal activity in the presence of ionic liquids

Dissertation presented to obtain the Ph.D degree in BiochemistryIonic liquids constitute a vast and heterogeneous group of chemicals, generally non-volatile and of high solvent quality. They are already used in industrial processes; future applications depend heavily on conscious design of ionic liquids. Given especially the global demand for sustainable chemicals, understanding environmental risks is a priority, necessitating a multidisciplinary research approach, covering a broad range of disciplines from biology to chemistry. Ascomycota fungi are highly suitable model organisms, especially due to their environmental ubiquity and important role in the biotic decay of pollutants. This thesis reports the first ever use of Ascomycota fungi to investigate ionic liquids ecotoxicity and environmental persistence. Fungal strains of Penicillium and Aspergillus were in general found to be more tolerant to ionic liquids containing imidazolium, pyridinium, pyrrolidinium, cholinium or phosphonium cations, than any other microorganism tested to date (Chapters II, III and IV). The capacity of the strains to tolerate the ionic liquids tested was apparently correlated to their phylogeny. Ionic liquid toxicity was evaluated using common parameters, such as growth inhibition and death. Less frequently evaluated parameters were also analysed, including monitoring of the integrity of the cellular boundaries of fungal conidia by microscopy (Chapter IV) and determining the diffusible fungal metabolome by ESI-MS and LC (Chapter II and V). Overall, these data significantly contribute to current understanding of structure-activity relationships in ionic liquids. For example toxicity is apparently a function of alkyl chain length of both anion and cation (Chapters III and IV, respectively). A critical review of current understanding of toxicity and environmental impact of the principal ionic liquid groups made it clear that the common generalisation of ionic liquids being either “green” or “toxic”(...)Financial support provided by Fundação para a Ciência e Tecnologia (fellowship BD 31451/2006). The work was partially supported by a grant from Iceland, Liechtenstein and Norway through the EEA financial mechanism (Project PT015)