From NANOplastics to bioplastics towards environmental sustainability: a green algae-based approach – NANOgrab

In 2018, over 360 million tons of plastic materials were produced and it is projected that the global production of thermoplastics will
amount to 445.25 million metric tons in 2025. At the end of their usage, plastic wastes are degraded into smaller particles becoming
microplastics (MPs) and nanoplastics (NPs). In aquatic environments, most MPs/NPs come from synthetic microfibers of
clothes/textiles shattered in household washing machines, among diverse sources.
Due to their endangering impact on the environment and human health, an effective and controlled management of MPs/NPs is
needed to avoid their huge release in the ecosystems. MPs/NPs removal along the wastewater treatment plants (WWTPs) indicates
high separation efficiency; however, while MPs are partially removed, NPs totally escapes treatment processes in significant
quantities due to their nanodimensions. Thus, further countermeasures are strongly required to upgrade WWTPs to efficiently
remove MPs/NPs and prevent their entering into rivers and the oceans.
NANOgrab proposes the development of a novel bioremediation strategy for water treatment to face NP pollution, based on cultures
of photosynthetic microorganisms, i.e. microalgae. Compared to bacterial systems, which may be considered as a biological
pollutant due to endotoxins and the requirement of a rich carbon source for growth, microalgae are a valid alternative, being
photoautotrophic organisms and not containing endotoxins, known to cause reactions in animals with symptoms of high fever,
vasodilation, diarrhea, and in extreme cases, fatal shock. Also, microalgal biomass, which should be disposed of as waste, can be
exploited to obtain added value compounds.
NANOgrab objectives are:
1. Obtainment of high efficiency microalgal strains that produce enzymes able to digest NPs: microalgae of fresh and marine water
sources will be selected for their ability of NP digestion by means of putative enzymes, identified by bioinformatics and
functionally/structurally characterized by spectroscopic techniques and biochemical assays. At the same time, model photosynthetic
microalgae will be genetically modified for the production of known and identified digestive enzymes selected among different
organisms (e.g. bacteria, fungi, animals), with the aim to obtain a synthetic organism with the desired features of NP digestion.
3. Conversion of microalgal biomass into added value products: the microalgal biomass produced within the bioreactor will be
exploited for the extraction of biopolymers for the production of added value compounds, e.g. bioplastics for packaging.