October, 2022, Leiden

Ph.D. thesis

The external tissues of plants and animals are colonized by microbial communities termed microbiota. When organisms are exposed to environmental pollutants, these substances will therefore encounter microbiota at the exposure interface. Many antimicrobial substances have been found to disturb beneficial interactions between microbiota and the host, thereby impairing host health. Nanomaterials exhibit nanoscale properties that could affect host health in two additional, understudied, microbiota-dependent ways. Firstly, owing to their large surface area, adsorption interactions between nanomaterials, microbial metabolites and microbes could alter the identity and colloidal stability of nanomaterials, and may influence the dispersal of microbes. Secondly, the immuno-modulatory effects of microbiota could affect the sensitivity of hosts to immunotoxic nanomaterials. In this dissertation, we use a combination of computational techniques and zebrafish larvae experiments to unravel and quantify these interactions. We predict the affinity of microbial metabolites to carbon and metal nanomaterials, and show that titanium dioxide nanoparticles can affect the dispersal of microbes through aquatic ecosystems, and across different life stages of oviparous animals. Additionally, we provide insight into microbiota-dependent signaling pathways that affect the sensitivity of zebrafish larvae to particle-specific, immunotoxic effects of silver nanoparticles. Altogether, these results contribute to mechanistic pathways for microbiota-inclusive nanomaterial safety assessment.

Key words: nanotoxicology, nanoparticles, host-microbiota interactions, particle-specific, adsorption, biocorona, inflammation, mechanistic pathways, zebrafish larvae, Danio rerio

Download my dissertation | Defense and propositions | Data