Abstract

Biorefineries are at the forefront of sustainable innovation, extracting and processing bioactive compounds from microorganisms and other biological sources for various applications in agriculture and food production. Among these compounds, astaxanthin (AXT) stands out for its remarkable antioxidant properties and significant health benefits. This study introduces a pioneering approach to developing a zero-waste, bacterial-based biorefinery by using microwave (MW)-assisted deep eutectic solvents (DES) for the extraction of astaxanthin-rich extracts (ARE) from Paracoccus carotinifaciens. Computational Fluid Dynamics (CFD) simulations was used to study the MW-ARE extraction process by accurately modeling the flow and mixing behaviors of DES during MW extraction, as well as the heat and mass transfer within the system. The DES enriched with ARE was thoroughly tested for their antifungal and anti-oomycete activity against Botrytis cinerea and Phytophthora cinnamomi, respectively, taking advantage of the high antioxidant and antimicrobial properties of ARE. Additionally, the remaining colorless fraction of P. carotinifaciens left after MW-ARE extraction was repurposed as a biofertilizer to enhance the growth of lettuce plants (Lactuca sativa L.). This comprehensive study provides a valuable insight into the mechanisms of ARE recovery using MW-assisted extraction and lay the groundwork for a robust, efficient, and sustainable biorefinery model that minimizes waste and maximizes the use of bacterial biomass, aligning with the principles of a circular economy, to elevate product quality and promote sustainable agricultural practices.