Prof. Auxi Prieto received her PhD in Pharmacy in the year 1995 from the Complutense University of Madrid in Spain. Currently, she is Research Professor at the Spanish National Research Council (CSIC) and Vice-president of the Spanish Society of Biotechnology. At the Biological Research Center Margarita Salas (CIB-CSIC), she is Head of the Polymer Biotechnology Group, which aims to explore and harness the bacterial ability to produce and biodegrade bio-based polymers. Using tools of microbial biotechnology that combine synthetic biology with materials science, her work focuses on sustainable production of bacterial polymers, the eco-design of bioplastics with tailor-made properties to meet target applications and solutions for their end-of-life.

---

Keynote Details

Wednesday 1 July

Symposium 23: Polymers and bioengineered materials

Bioplastics Circularity: From Natural Biopolymers to Bio-Inspired Functional Materials

Increasing environmental concerns about plastic pollution have accelerated the global transition toward a circular economy. In this context, bioplastics represent a promising and sustainable alternative, enabling a more environmentally friendly plastic life cycle. Among them, polyhydroxyalkanoates (PHAs) and bacterial cellulose (BC) are key examples of microbial polymers that can replace fossil-based synthetic materials. These polymers are particularly well suited for circular economy models because they are both synthesized and biodegraded entirely by microorganisms. If properly harnessed, this intrinsic circularity provides a strong foundation for the development of sustainable functional materials.

Modern systems biotechnology plays a role in this transition by enabling the engineering of microbial strains capable of converting waste substrates into valuable biopolymers. At the same time, the structural diversity and functionality of bacterial polymers can be expanded through strategies. One approach combines metabolic engineering and synthetic biology to design microorganisms that produce polymers with chemical structures and better material properties. A second strategy involves the introduction of new functionalities through peptide tags derived from PHA-associated proteins, such as phasins. These proteins are essential for PHA granule formation and metabolism and have emerged as tools for functionalizing PHA surfaces. Minimized versions of these proteins have been developed to enable in vitro association with hydrophobic materials. A third approach focuses on polymer compatibilization to create bio-based blends. In this context, living PHA-producing bacteria can act as functional agents to enhance the barrier properties of cellulosic materials by depositing PHA within the pores of hydro- and aerogels.