Host and microbiome proteins in eco-coronas: abundance, physicochemical properties and binding partners

Abstract

Nanoparticles sequester biomolecules from their immediate surroundings through chemi- and physisorption interactions. In ecosystems, these biomolecules form a transient ‘face’ on the particle surface, termed the eco-corona. Through bio–nano interactions, proteins of host-associated microbiomes can interact with eco-coronas, potentially altering the identity and behavior of nanomaterials. Here, microbiome proteins in eco-coronas from the common ecotoxicological tests species Daphnia magna and Danio rerio were characterized on carbon nanotubes and titanium dioxide nanoparticles using a combination of LC–MS/MS-based proteomics and metagenomic sequencing. In total, 520 D. magna proteins, 1444 D. rerio proteins, and 1405 and 441 proteins of their respective microbiomes were identified. Analysis of their binding partners indicated that these host and microbiome proteins can facilitate the additional recruitment of anions, cations, proteins, carbohydrates and lipids in eco-coronas. In terms of their physicochemical properties, microbiome proteins were smaller and provided areas with higher polarity and more cationic charge than host proteins. These results thereby reveal how microbiome proteins can alter nanomaterial surface properties. Furthermore, the present study suggests that the identity of microbiome proteins in eco-coronas can provide useful information on nanomaterial transport through ecosystems, especially when experimental studies on microbiome–nanomaterial interactions are executed in the presence of the host.