Polyhydroxybutyrate-co-valerate (PHBV) is a widely used copolymer from the polyhydroxyalkanoate family. Its biocompatibility and biodegradability make it a promising alternative to conventional plastics. However, the environmental impact of PHBV microplastics remains poorly understood. This study examines the physiological effects of primary PHBV microplastics on the zooplankton model Artemia franciscana, focusing on key endpoints such as survival, growth, feeding rate, developmental stage, gut histology, and lipid composition including fatty acid profiles, lipid storage and lipid peroxidation. Experiments involved short-term (24-48 h) and long-term (7-14 days) exposures to varying PHBV concentrations (10 to 500 mg·L-1). PHBV biopolymer characterization through FTIR, laser diffraction techniques and SEM was done. Results indicated high survival across developmental stages, even when nauplii and juveniles were exposed to PHBV without food for up to 7 and 14 days, respectively. Notably, growth increased significantly at higher PHBV concentrations in presence of microalgae after 14 days. Long-term exposure at high PHBV concentrations altered the fatty acid profile with a concomitant decrease in lipid peroxidation. Also, it affected the cytoarchitecture of the digestive epithelium. Ingestion and egestion of PHBV microparticles were observed. SEM imaging revealed alterations in surface roughness between initial PHBV particles and those recovered from fecal pellets. These results involve distinctive physiological responses that may involve energy utilization from PHBV degradation and/or its action as a therapeutic agent. Overall, this research aims to enhance understanding of the ecological risks posed by biodegradable microplastics in aquatic ecosystems and their emerging role in global aquatic plastic pollution.

Aquatic organisms are exposed to multiple stressors, including microplastic pollution and rising temperatures. Bioplastics like Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are considered sustainable alternatives to conventional plastics, although their biological effects remain poorly understood. This study evaluated the effects of PHBV microplastics on Artemia franciscana under different temperature and exposure conditions. Organisms were exposed to 25 and 100 mg·L−1 PHBV for 7, 14, and 21 days at 25 °C and for 14 days at 29 °C. Growth, development, antioxidant enzyme (CAT, GST) and esterase activities (ChE, CbE), lipid peroxidation (LPO), gut histology, fatty acid profiles and polymer particle length distributions were assessed. Growth and development increased with PHBV concentration, exposure time, and temperature. Enzymatic activities and LPO were significantly affected by these factors, although no evidence of oxidative damage was detected. Marked gut lesions were observed at 100 mg·L−1 PHBV at 29 °C after 14 days. Fatty acid profiles were mainly influenced by time and temperature, while high PHBV levels were associated with additional, more subtle changes in long-chain polyunsaturated fatty acids. PHBV particle length distributions also varied depending on exposure conditions. These findings suggest that PHBV induces physiological responses distinct from those typically reported for conventional microplastics and highlight the importance of considering multiple stressors in ecotoxicological studies.

Natural rubber's main component, a cis-1,4-polyisoprene polymer, traditionally requires vulcanization for stabilization, which complicates the degradation, recycling, and environmental impact. To address these challenges, a sustainable alternative has been developed, a novel elastomeric material using depolymerized cis-1,4-polyisoprene (liquid natural rubber-PI) and electrospinning, in a blend with a copolymer of the polyhydroxyalkanoate (PHA). PI was blended with poly(3-hydroxybutyrate-co-4-hydroxybutyrate) P3HB4HB, but the blends with >10% polyisoprene were unstable due to immiscibility. This was resolved by the addition of 5% w/w of high molecular weight poly(ethylene oxide) (PEO), forming a ternary blend. Two materials were created: a binary blend with 10% w/w and a ternary with 64% w/w polyisoprene. Both exhibited high elongations at break (300-1400%), toughness surpassing individual components, comparable to or exceeding values reported for some elastomeric systems. The binary blend showed enhanced hydrophobicity, strength, elasticity, and compostability, suitable for biodegradable elastomeric bands, while the ternary blend showed unique morphology as a combination of fibers and continuous film, high elasticity, and adaptability, exhibiting film-like properties.

Marine phototrophic bacteria represent promising platforms for sustainable microbial biopolymer production. Here, we report the screening and functional characterization of MAR44, a Mediterranean isolate identified as the aerobic anoxygenic phototrophic bacterium (AAPB) Roseibium alexandrii. This strain carries a complete set of genes for polyhydroxyalkanoate (PHA) metabolism, including phaC, phaAB, phaR, phaZ and multiple phaP homologues. Phenotypic screening confirmed substantial intracellular PHA accumulation, and gravimetric determination revealed intracellular polymer contents of up to approximately 50% of cell dry weight. The purified polymer exhibited the characteristic FTIR absorption bands and 1H NMR signals associated with PHAs. A key finding is that illumination significantly (p < 0.05) increased glucose-induced intracellular PHA accumulation. Under continuous illumination and long-day photoperiods, MAR44 showed higher mean intracellular PHA accumulation levels, with increases of up to approximately two-fold compared with short-day conditions. These results suggest an association between illumination and enhanced intracellular PHA accumulation in this AAPB, although the underlying mechanisms remain to be elucidated. This study also introduces MAR44 as a promising candidate for further research into light-supported biopolymer production, expanding the current set of organisms beyond traditional soil-derived producers such as Cupriavidus necator.

In this study, electrospun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) biopapers were produced by annealing electrospun fiber mats from two commercial grades (151C and X131A) and compared with films prepared by the conventional melt-mixing/compression molding method. To obtain continuous biopapers, the fiber mats were subjected to mild thermal post-processing at various temperatures. The selected annealing temperatures were 140 °C (151C) and 130 °C (X131A), where interfiber coalescence occurred within a short annealing time (10 s), yielding continuous fibrous films (biopapers). To elucidate the structural mechanisms underlying interfiber coalescence, time-resolved synchrotron SAXS/WAXS and temperature-dependent FTIR spectroscopy were performed. These analyses showed that coalescence occurred through an interplay between thermally induced local ordering at sub-melting temperatures and premelting/partial melting of thin, ill-defined lamellae, with grade-dependent contributions. The resulting biopapers were evaluated against compression-molded films for optical, mechanical, and barrier properties relevant to packaging. All samples showed similar transparency, although compression-molded films were slightly more opaque. The lower-rigidity grade (151C) exhibited more ductile and tougher behavior than X131A. Biopapers showed slightly lower water and oxygen barrier performance than compression-molded films, attributed to differences in material compactness. Overall, brief mild annealing after electrospinning enabled continuous PHBH biopapers with balanced properties, supporting their potential for sustainable PHBH-based food-packaging applications.

The growing demand for sustainable packaging has accelerated the development of biodegradable, bio-based alternatives to traditional plastics [...]

The present study explores the remarkable capabilities of deep eutectic solvents (DES) for enhancing the antioxidant properties of films containing the natural antioxidant resveratrol (Res). A key achievement of this work is the unprecedented solubility of resveratrol400 mg/mLin a highly effective DES composed of choline chloride (ChCl) and ethylene glycol (EG), representing a significant enhancement over previously reported values. For the active and sustainable packaging development purposes, this was coupled with the creation of continuous and nonporous electrospun poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biopaper material through electrospinning and subsequent thermal annealing processes, featuring enhanced antioxidant properties. Remarkably, a second achievement of this paper is that electrospun biopapers containing DES-solubilized Res exhibited a 30% improvement in antioxidant activity and material efficiency compared to those containing the same amount of nonsolubilized resveratrol within the polymer. Additionally, characterization was made via wide-angle X-ray diffraction, optical properties, mechanical and barrier testing, demonstrating that the studied DES not only optimized the functional attributes of PHBV biopapers but also maintained their structural integrity and mechanical and barrier performance. Therefore, this study highlights the potential of DES as a potent tool for improving the effectiveness of poorly soluble natural antioxidants, paving the way for the development of innovative solutions in active and sustainable packaging.

Polyhydroxyalkanoates (PHAs) are receiving significant attention due to their biobased origin, biodegradability, and excellent barrier properties. However, their high cost compared to traditional plastics necessitates the development of recycling technologies to retain their value post-use. Despite being thermoplastics, PHAs are difficult to recycle mechanically due to their narrow processing window, particularly for polyhydroxybutyrate (PHB), and conventional chemical recycling routes often lead to non-selective degradation and dehydration to crotonic acid, yielding complex product mixtures with limited valorization potential. In contrast, this study presents a selective chemical recycling method for PHB that suppresses dehydration pathways by using naturally occurring taurine as an organocatalyst. Taurine outperforms other catalyst families, such as Brønsted acids and bases, in terms of depolymerization yield and selectivity, achieving 98% enantiomerically pure 3-hydroxybutyric acid (HBA) in the optimized process. Density functional theory (DFT) calculations provided insights into the pH-dependent HBA elimination mechanisms demonstrating that taurine does not play a role in this process under very basic nor acidic conditions. A liquid-liquid extraction technique was developed to separate HBA from by-product crotonic acid, successfully maintaining the R-enantiomeric form of the recovered HBA. This method is applicable to both synthetic PHB and biological PHB samples, including copolymers and blends. Overall, this taurine-catalyzed PHB depolymerization approach inhibits the formation of dehydrated by-products and offers a promising solution for selective recycling of PHB into valuable chiral building blocks.

A vast amount of plastic waste enters the ocean every year and the Mediterranean Sea is particularly affected by this issue. Biodegradable polymers like poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), may help mitigate this problem. We investigated bacterial biofilm development and succession on these polymers over one year in the Western Mediterranean Sea. Scanning electron microscopy (SEM) and confocal laser scanning were used to examine microbial colonization and surface erosion, while bacterial community abundance and composition were assessed through culture plate counting and 16S rRNA gene amplicon sequencing. SEM revealed significant surface erosion on PHBV, indicative of microbial degradation, while PLA exhibited minor and irregular erosion. Culture-based quantification showed higher bacterial colonization on PHBV compared to PLA, suggesting that PHBV provides a more favourable surface for bacterial attachment Amplicon sequencing of the 16S rRNA gene revealed high bacterial diversity, with 17,781 operational taxonomic units across all samples. Proteobacteria, Bacteroidota, and Planctomycetota were the dominant phyla, with the Shannon index consistently exceeding 8, corroborating the bacterial diversity across all materials. Temporal shifts in bacterial community composition were significant, with exposure time explaining 29.8 % of the variation, suggesting biofilm succession as a key factor shaping microbial assemblages. While polymer type had a limited impact on bacterial composition, PHBV biofilms exhibited greater bacterial abundance and diversity compared to PLA. This study highlights PHBV's role in shaping biofilms and its relevance in assessing biodegradable plastics in marine environments. Understanding microbial interactions with bioplastics is crucial for evaluating their environmental impact and degradation dynamics.

Biodegradable polymers have been proposed as a possible solution to plastic pollution in the ocean but there is still a lack of knowledge about their behavior in this particular ecosystem due to the great variability of marine habitats. The abiotic and biotic deterioration of biodegradable polymers -polylactic acid (PLA) and poly(3hydroxybutyrate-co-3-hydroxyvalerate), (PHBV) - and conventional polymers - polyamide 6/6.6 copolymer (PA), polypropylene (PP) and polyethylene (PE) - were studied throughout 12 months of immersion in the western Mediterranean sea. The behavior of PLA was not distinct from that of the non-biodegradable plastics. PA, PE and PP only showed small changes derived from their interaction with the marine environment. Their low mass reduction and attrition of mechanical properties were ascribed to abiotic factors. Biodegradation was clearly observed only for the PHBV, reaching a 16 % of weight loss in the registered period and showing an increased surface roughness, and higher biofilm density than the rest of materials. However, as time progressed, a noticeable reduction in the biodegradation rate was observed. This decline may be attributed to a limitation of optimal conditions for microorganisms on the material's surface, likely influenced by the unique characteristics of the surrounding environment, such as biofouling, pollution, and temperature variations. FTIR experiments confirmed the layer-by-layer degradation mechanism starting from amorphous zones. This is a step forward in understanding the degradability of polymers in specific marine environments required for developing prediction systems of plastics' lifetime in the ocean.

In this study, the use of deep eutectic solvents (DESs) was considered for the first time to improve the mechanical properties of electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fiber mats. For this, different DES formulations, namely, Choline Chloride (ChCl):Urea:Water, ChCl:Glycerol (Gly), and Gly:Sodium Citrate (NaCitrate), were selected and evaluated at a concentration of 10 wt %, and their efficacy enhancing mechanical properties was compared against traditional plasticizing additives glycerol and acetyl tributyl citrate (ATBC). The impact of these formulations on PHBV fiber mats was evaluated in terms of thermal, crystallinity, and mechanical properties, both as obtained and after aging. All samples produced macroscopically consistent, self-supporting, and handleable nonwoven material sheets. The DES-containing PHBV showed a thinner, bead-free surface morphology but a rugose surface morphology. DSC results indicated that glycerol, ATBC, and Gly:NaCitrate (DES) exhibited the highest reduction in melting temperatures, with a notable 5.6 °C decrease for the mat containing Gly:NaCitrate. Interestingly, electrospun PHBV fibers containing DES revealed a larger quantity of β-form planar zigzag chain conformations, so-called β-form crystals. Tensile test results revealed that depending on the additive formulation, the mechanical performance of the samples was fundamentally different from each other. Among DESs, PHBV fiber mats with ChCl-based DES were excessively brittle. Surprisingly and interestingly, PHBV fiber mats containing Gly:NaCitrate exhibited an unreported significant increase in all mechanical properties, including modulus, elongation at break, and toughness. Overall, this study highlights the potential of DESs as unique additives to tailor the mechanical properties of electrospun PHBV materials.

We report here the genome sequence of Roseibium alexandrii strain MAR44, an alpha-proteobacterium isolated from an experimental device to monitor bioplastics colonization in the Mediterranean Sea. The genome assembly comprises a total of 5.25 Mb with a GC content of 56.33% and 5,019 predicted genes. Genome annotation reveals that MAR44 strain contains several pha genes involved in the polymerisation and depolymerisation of polyhydroxyalkanoates; phaA, phaB and phaC encode for the enzymes responsible of the last steps of the biosynthetic pathway, whereas phaZ encodes for a PHA-depolymerase. We also identified the phaR regulator and four phaP genes encoding for phasin proteins with a role in folding and accumulation of PHA in subcellular granules. In addition, we identified a photosynthesis gene cluster including the bch genes for the bacteriochlorophyll a synthesis and the puf operon encoding photosynthetic reaction centre and light-harvesting genes. In another manuscript we describe the efficient production of PHA by this strain under different conditions of carbon source supplementation and photosynthetic light.

Plastic pollution has become one of the most pressing environmental issues worldwide, with large amounts of conventional plastics accumulating in terrestrial and marine ecosystems due to their persistence and ineffective waste management. Developing and understanding the biodegradation behavior of environmentally friendly alternatives, such as bioplastics, is therefore crucial to mitigate this problem. In this context, the degradation of PHBV-based biocomposites containing purified cellulose (TC), wood flour (WF), and almond shell (AS) fibers have been investigated and compared with neat PHBV in two Mediterranean marine locations—a port and the open sea, within the same geographic region. Changes in weight, surface morphology, surface roughness, surface chemistry, and mechanical properties were monitored and periodically evaluated over 18 months of seawater exposure at the two sites. After 18 months of immersion, PHBV/AS showed the highest disintegration degree (88

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a very promising biodegradable copolyester of high interest in food packaging. Its inherent brittleness and narrow processing window make it necessary to blend it with flexible biopolyesters, such as poly(butylene succinate-co-adipate) (PBSA). However, the resultant biopolyester blends are thermodynamically immiscible, which impairs their performance and limits their applications. This study is the first to explore the use of poly(butylene succinate-co-adipate) grafted with maleic anhydride (PBS-g-MAH) as a novel reactive additive to compatibilize PHBV/PBSA blends. The compatibilizer was prepared by a reactive melt-mixing process of PBSA and maleic anhydride (MAH) using dicumyl peroxide (DCP) as an organic radical initiator, achieving a grafting degree (Gd) of 5.4%. Biopolyester blend films were thereafter prepared via cast extrusion and their morphological, thermal, mechanical, and barrier properties were characterized. Compatibilization by PBSA-g-MAH was confirmed by observing an improved phase interaction and lower dispersed domain sizes in the blends with 15 wt% PBSA. These compatibilized PHBV/PBSA blends were thermally stable up to 285 °C, showed enhanced ductility and toughness, as well as providing an improved barrier against water and limonene vapors and oxygen. These findings suggest that the use of MAH-grafted biopolyesters can represent an effective strategy to improve the properties of biopolyester blends and open up new opportunities for the application of PHBV-based formulations for food packaging.

Plastic pollution in the form of microplastics (MPs), poses a significant threat to natural ecosystems, with detrimental ecological, social, and economic impacts. This review paper aims to provide an overview of the existing research on the interaction between microbial biofilms and MPs in natural environments. The review begins by outlining the sources and types of MPs, emphasizing their widespread presence in marine, freshwater, and terrestrial ecosystems. It then discusses the formation and characteristics of microbial biofilms on MPs surfaces, highlighting their role in altering the physicochemical properties of MPs and facilitating processes such as vertical transport, biodegradation, dispersion of microorganisms, and gene transfer. Different methods used to assess these interactions are discussed, including microbiological and physicochemical characterization. Current gaps and challenges in understanding the complex relationships between biofilms and MPs are identified, highlighting the need for further research to elucidate the mechanisms underlying these complex interactions and to develop effective mitigation strategies. Innovative solutions, including bioremediation techniques and their combination with other strategies, such as nanotechnology, advanced filtration technologies, and public awareness campaigns, are proposed as promising approaches to address the issue of MPs pollution. Overall, this review underscores the urgent need for a multidisciplinary approach to combating MPs pollution, combining scientific research, technological innovation, and public engagement to safeguard the health and integrity of natural ecosystems.

Surgical site infections (SSI) occur very frequently during post-operative procedures and are often treated with oral antibiotics, which may cause some side effects. This type of infection could be avoided by encapsulating antimicrobial/anti-inflammatory drugs within the surgical suture materials so that they can more efficiently act on the site of action during wound closure, avoiding post-operative bacterial infection and spreading. This work was aimed at developing novel electrospun bio-based anti-infective fibre-based yarns as novel suture materials for preventing surgical site infections. For this, yarns based on flying intertwined microfibres (1.95 ± 0.22 µm) were fabricated in situ during the electrospinning process using a specially designed yarn collector. The electrospun yarn sutures (diameter 300–500 µm) were made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with different contents of 3HV units and contained ciprofloxacin hydrochloride (CPX) as the antimicrobial active pharmaceutical ingredient (API). The yarns were then analysed by scanning electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray scattering, differential scanning calorimetry, and in vitro drug release. The yarns were also analysed in terms of antimicrobial and mechanical properties. The material characterization indicated that the varying polymer molecular architecture affected the attained polymer crystallinity, which was correlated with the different drug-eluting profiles. Moreover, the materials exhibited the inherent stiff behaviour of PHBV, which was further enhanced by the API. Lastly, all the yarn sutures presented antimicrobial properties for a time release of 5 days against both Gram-positive and Gram-negative pathogenic bacteria. The results highlight the potential of the developed antimicrobial electrospun yarns in this study as potential innovative suture materials to prevent surgical infections.

Four different end-of-life options for disposable bioplastic cups were investigated and compared based on their environmental implications. Two products with distinct polymeric composition were tested simulating the following scenarios at laboratory scale: i) industrial composting (180 days at 58 °C); ii) anaerobic digestion followed by industrial composting (45 days at 55 °C and 180 days at 58 °C); iii) anaerobic digestion followed by direct digestate use on soil for agricultural purposes (45 days at 55 °C and 180 days at 25 °C); iv) uncontrolled release into a soil environment (180 days at 25 °C). Ecotoxicity tests were run at the end of each experiment to investigate the effects of the materials on three main groups of terrestrial model organisms: plants, earthworms and nitrifying bacteria. Complete biodegradation of the cups was observed in 180 days in the scenarios involving composting environment. A low degree of biodegradation (22.9 ± 4.5%) of the digestates in soil was observed, warning for a potential micro-bioplastics discharge into the environment. No degradation was observed for the cups in soil during the same testing period. Ecotoxicity tests revealed a negative effect on plants biomass growth across all samples, which was 17–30% lower compared to the blank sample. The experimental campaign highlighted the need for a systematic assessment of controlled treatment of bioplastics, as well as the need for a harmonized legislative framework.

This study investigates the unique morphology and mechanical properties of multi-jet electrospun cashew gum (CG) when combined with high-molecular-weight polyethylene oxide (PEO) and glycerol. Cashew gum (CG) is a low-cost, non-toxic heteropolysaccharide derived from Anacardium occidentale trees. Initially, the electrospinnability of aqueous solutions of cashew gum alone or in combination with PEO was evaluated. It was found that cashew gum alone was not suitable for electrospinning; thus, adding a small quantity of PEO was needed to create the necessary molecular entanglements for fiber formation. By using a single emitter with a CG:PEO ratio of 85:15, straight and smooth fibers with some defects were obtained. However, additional purification of the cashew gum solution was needed to produce more stable and defect-free straight and smooth fibers. Additionally, the inclusion of glycerol as a plasticizer was required to overcome material fragility. Interestingly, when the optimized formulation was electrospun using multiple simultaneous emitters, thicker aligned fiber bundles were achieved. Furthermore, the resulting oriented fiber mats exhibited unexpectedly high elongation at break under ambient conditions. These findings underscore the potential of this bio-polysaccharide-based formulation for non-direct water contact applications that demand elastic properties.

In the present study, a multilayer, high-barrier, thin blown film based on a polybutylene adipate terephthalate (PBAT) blend with polyhydroxyalkanoate (PHA), and composed of four layers including a cellulose nanocrystal (CNC) barrier layer and an electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) hot-tack layer, was characterized in terms of the surface roughness, surface tension, migration, mechanical and peel performance, barrier properties, and disintegration rate. The results showed that the film exhibited a smooth surface. The overall migration tests showed that the material is suitable to be used as a food contact layer. The addition of the CNC interlayer had a significant effect on the mechanical properties of the system, drastically reducing the elongation at break and, thus, the flexibility of the material. The film containing CNCs and electrospun PHBV hot-tack interlayers exhibited firm but not strong adhesion. However, the multilayer was a good barrier to water vapor (2.4 ± 0.1 × 10−12 kg·m−2·s−1·Pa−1), and especially to oxygen (0.5 ± 0.3 × 10−15 m3·m−2·s−1·Pa−1), the permeance of which was reduced by up to 90% when the CNC layer was added. The multilayer system disintegrated completely in 60 days. All in all, the multilayer system developed resulted in a fully compostable structure with significant potential for use in high-barrier food packaging applications.