Upcycling Biodegradable PVA/Starch Film to a Bacterial Biopigment and Biopolymer

Abstract

Meeting the challenge of circularity for plastics requires amenability to repurposing post-use, as equivalent or upcycled products. In a compelling advancement, complete circularity for a biodegradable polyvinyl alcohol/thermoplastic starch (PVA/TPS) food packaging film was demonstrated by bioconversion to high-market-value biopigments and polyhydroxybutyrate (PHB) polyesters. The PVA/TPS film mechanical properties (tensile strength (σu), 22.2 ± 4.3 MPa; strain at break (εu), 325 ± 73%; and Young’s modulus (E), 53–250 MPa) compared closely with low-density polyethylene (LDPE) grades used for food packaging. Strong solubility of the PVA/TPS film in water was a pertinent feature, facilitating suitability as a carbon source for bioprocessing and microbial degradation. Biodegradability of the film with greater than 50% weight loss occurred within 30 days of incubation at 37 °C in a model compost. Up to 22% of the PVA/TPS film substrate conversion to biomass was achieved using three bacterial strains, Ralstonia eutropha H16 (Cupriavidus necator ATCC 17699), Streptomyces sp. JS520, and Bacillus subtilis ATCC6633. For the first time, production of the valuable biopigment (undecylprodigiosin) by Streptomyces sp. JS520 of 5.3 mg/mL and the production of PHB biopolymer at 7.8% of cell dry weight by Ralstonia eutropha H16 from this substrate were reported. This low-energy, low-carbon post-use PVA/TPS film upcycling model approach to plastic circularity demonstrates marked progress in the quest for sustainable and circular plastic solutions.

Colonization and Biodegradation Potential of Fungal Communities on Immersed Polystyrene vs. Biodegradable Plastics: A Time Series Study in a Marina Environment

“…Penicillium brevicompactum C2559 was isolated from a nine-week-immersed PLA sample, which corresponds to a PLA sample that also had an ASV associated with the genus Penicillium in our metabarcoding data, and cultured using on a PS-supplemented medium. A previous study has demonstrated the ability of this species to degrade polyvinyl alcohol (PVA) [ 70 ], a polymer considered as biodegradable [ 71 , 72 ], which appears consistent with our results demonstrating a potential for another biodegradable polymer, here PCL [ 73 ]. Such capabilities may be explained by their shared properties.…”

Research Progress of Polyvinyl Alcohol Water-Resistant Film Materials

“…After PVA and starch were mixed, the water absorption decreased compared to pure PVA due to hydrogen bonding between PVA and starch, which affected the number of free -OH groups [ 51 , 52 ]. Pantelic et al [ 53 ] mixed thermoplastic starch (TPS) and PVA 1:1 to produce PVA/TPS film by extrusion. From the FTIR spectrum of the PVA/TPS film, the presence of a broad peak in the area of 3200–3500 cm −1 could be attributed to the vibrational stretching of hydroxyl (–OH) groups due to the inter- and intra-molecular hydrogen bonding of –OH groups in the PVA and starch.…”

Biodegradable Temperature Sensor enabled using Printed Electronics

“…Among these, we choose PVA as a substrate in our study owing to their biodegradability, high water-solubility and the ease of production. [3] By using these biodegradable polymer substrates, we can mitigate the adverse effects of traditional plastics on ecosystems, marine life, and human health. Additionally, they offer versatility in applications while maintaining functionality and durability.…”