Abstract
Transitioning towards a circular bioeconomy requires sustainable routes for producing high-value biopolymers from renewable and waste-derived resources. The Horizon Europe-funded project BIONEER addresses this by developing and scaling up bio-based chemicals and polymers from waste biomass, combining biotechnology and chemistry to replace fossil-based materials in UV-curable coatings and personal care products. A key objective is the sustainable production of microbial alginate using industrial side streams, with tailored properties achieved through downstream processing. Alginate is a linear polysaccharide composed of β-D-mannuronic acid (M) and α-L-guluronic acid (G), valued for its versatile physicochemical properties. While traditionally extracted from brown algae, it can also be produced via microbial fermentation. In this study, lignocellulosic hydrolysates from industrial side streams were successfully used as feedstocks, yielding up to 12 g/L alginate, comparable to standard carbon sources, demonstrating the potential of waste-derived substrates. Following fermentation, alginate was purified using tailored downstream processes to ensure high purity. Low molecular weight alginate (<1 kDa), obtained by acid hydrolysis, was suitable for functionalisation in UV-curable coatings. Medium molecular weight alginate (100–400 kDa) was produced via fermentation control and/or hydrolysis, targeting personal care applications requiring specific rheological and film-forming properties. Alginate fractions of different molecular weights recovered directly from fermentation broth were also used for hydrogel formulations for healthcare applications. For the two latter, charcoal-based purification effectively removed residual proteins and endotoxins. This work demonstrates how combining waste feedstock valorisation, scalable bioprocessing, and molecular tailoring enables sustainable production of functional biopolymers for diverse high-value applications.