Ameya Pankaj Gupte

Wine production generates significant quantities of by-products each year, among which surplus grape must is notable for its high content of fermentable sugars, organic acids, and polyphenols. As wine consumption declines and grape must surpluses grow, identifying sustainable valorization strategies becomes increasingly critical. This study investigates for the first time the potential use of red and white grape musts as substrates for polyhydroxyalkanoates (PHAs) production by two well-characterized bacterial strains, Cupriavidus necator DSM 545 and Hydrogenophaga pseudoflava DSM 1034, under both batch and fed-batch fermentation regimes. Both musts supported microbial growth and PHAs accumulation. In batch cultures, C. necator DSM 545 achieved a PHB content of up to 61.5% of cell dry weight (CDW), while H. pseudoflava DSM 1034 reached 67.9% PHB on grape must, with yields and biomass comparable to or exceeding those obtained with synthetic sugar-based media. Under fed-batch conditions with red must, C. necator DSM 545 sustained growth and PHB production across multiple feeding feeding periods, outperforming the control medium. Conversely, H. pseudoflava DSM 1034 displayed initial growth but failed to increase biomass over time, suggesting that this strain may be poorly suited for use in fed-bacth-based applications, likely due to nutrient depletion or the accumulation of inhibitory compounds. Overall, these results proved that grape musts are promising feedstocks for sustainable PHAs production. Their integration into circular economy frameworks offers a valuable opportunity for waste recovery and the development of bioplastics within the agri-food industry, especially in light of the increasing grape must surpluses recently experienced worldwide.

Printed circuit boards (PCBs) are essential components of nearly all electronic products and consist mostly of laminated structures combining conductive and insulating layers. Conventional PCB manufacturing relies on fossil-based and poorly degradable materials. Most widely used components are the fiberglass FR-4 for rigid substrates and polyethylene terephthalate (PET) for flexible substrates. When improperly managed at the end-of-life stage, PCBs pose significant environmental and health risks. Current disposal practices, including incineration and e-waste storage, contribute to the release of carcinogenic and persistent pollutants such as dioxins and polycyclic aromatic hydrocarbons, with severe impacts on ecosystems and human health. Consequently, there is an urgent need to develop simplified recycling strategies and to adopt environmentally friendly materials for both substrates and processing reagents. Polyhydroxyalkanoates (PHAs) represent a promising class of biopolymers synthesized by microorganisms. PHAs combine functional performance with intrinsic biodegradability and enable controlled degradations of electronic substrates after disposal. In recent studies, PHAs were investigated as sustainable PCB substrate materials, processed through additive manufacturing techniques such as drop casting, spray coating, inkjet printing, and laser activation to support material-efficient and low-impact fabrication routes. The surface morphology and topography of the surface of the substrates were characterized using optical profilometry, while cross-section analyses and scanning electron microscopy were employed to evaluate layer integrity, microstructure, and interfacial quality. Thermal properties were evaluated by thermogravimetric analysis. In addition, eco-friendly solvent-based approaches were explored for the recovery and recycling of materials, aiming to close the material loop and enhance circularity. Overall, the integration of biodegradable polymers, advanced manufacturing techniques, comprehensive material characterization, and green recycling strategies suggest viable pathways toward environmentally responsible microelectronics and support the transition to a more sustainable future for electronic materials.