Search Results (573)

Second cheese whey (SCW), a major by-product of ricotta cheese production, poses significant environmental challenges due to its high organic load. Biohydrogen (bio-H₂) and poly-β-hydroxybutyrate (PHB) production offer a sustainable reuse of SCW, that provides ideal nutrients for microbial growth. This study aimed to convert SCW into Bio-H₂ and PHB using a 5-liter tubular bioreactor in a sequential lactic fermentation and photofermentation system. Two lighting conditions were tested: white LED (WL) and selected LED (SL). Optimal results were achieved with a co-inoculum of Lactococcus lactis MK L84 and Lacticaseibacillus paracasei MK L49 at pH 4.5–5.5, followed by photofermentation with Rhodopseudomonas palustris 42OL under SL condition. The process yielded an average of 0.47 L of H₂ per liter of substrate and 1.66% wPHB/wCDW. This approach successfully transformed dairy waste into high-value products, promoting circular economy principles. Full article

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable polyester considered for food packaging, though its mechanical and barrier limitations pose challenges. This study assessed PHBV/TiO₂ nanocomposites for packaging applications. Differential scanning calorimetry revealed reduced crystallinity and lower melting points with an increase in TiO₂ content. Thermal stability improved at 1% and 3% TiO₂, raising onset temperatures to 283 °C and 284 °C, respectively. Scanning electron microscopy and FTIR confirmed uniform nanoparticle dispersion without agglomeration. Tensile tests showed decreasing strength and modulus from 1% to 7% TiO₂, with peak elongation at 3%, whereas viscosity behavior declined with higher nanoparticle loading. Low portions of nanoparticles (1% and 3%) induced the improvement in barrier properties against oxygen and water vapor. The highest biodegradation rate occurred at 7% TiO₂. Overall, the nanocomposites’ properties tend to deteriorate with the addition of higher portions of TiO₂. Thus, despite some improvements, the nanocomposites did not deliver consistent, multi-property enhancements to justify use in food packaging. Key metrics like sealability and appearance were not evaluated. Future research should explore surface-treated TiO₂, alternative fillers, compatibilizers, and optimized processing, alongside standardized safety assessments for food-contact applications. Full article

Poly(hydroxyalkanoates) (PHAs) have garnered significant attention due to their biodegradable and biocompatible properties, making them promising alternatives to conventional petroleum-based plastics. As microbial-derived polyesters, PHAs offer a sustainable solution to plastic waste accumulation and microplastics because they can be produced from renewable resources, including food-related waste. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer in the PHA family, exhibits improved mechanical flexibility and thermal properties compared to poly(3-hydroxybutyrate), thereby broadening its potential applications. In this work, eight samples of PHBV, including those made from food waste and municipal waste streams, were studied by solid-state NMR. Information obtained includes the copolymer composition, chemical shifts due to crystalline lattices, crystallinity, and polymer chain mobility. The composition matches the results from the fatty acid feed and solution NMR analysis. The samples appear to be about 62–70% crystalline. No significant differences in mobility are observed from NMR relaxation data. These results indicate that PHBV materials generated from different food-related waste sources, despite their compositional differences, possess similar crystallinity and molecular mobility, suggesting their suitability as biobased semi-crystalline plastics. Full article

The growing demand for sustainable materials in a circular economy necessitates the evaluation of the recyclability of biodegradable composites. This study aims to investigate the effect of multiple mechanical recycling cycles on the properties of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposite containing 45 wt% spent coffee grounds (SCG). The material was produced via extrusion and injection molding, followed by five consecutive recycling cycles under controlled processing parameters. Changes in mechanical properties (tensile strength, elastic modulus, elongation at break, hardness, and impact tensile strength), processing shrinkage, thermal structure (DSC), and microstructure (SEM) were evaluated. The results revealed a gradual increase in PHBV crystallinity, confirmed by DSC analysis. Consequently, the changes in mechanical properties were significant; specifically, the elastic modulus increased by approximately 9.6% and hardness improved, whereas elongation at break decreased by approx. 18% and impact strength declined, indicating a transition towards a stiffer but more brittle material. SEM observations suggested microstructural evolution with reduced agglomerates after subsequent cycles and the predominance of a brittle fracture mechanism. Linear shrinkage in the flow direction remained stable, whereas changes in thickness shrinkage correlated with the formation of micropores. The findings demonstrate that PHBV-SCG biocomposites maintain adequate mechanical and processing performance even after five recycling cycles, highlighting their potential for applications within a circular economy framework. Full article

The application of bioabsorbable PhasixST™ mesh in the laparoscopic repair of large hiatal hernias has emerged as a promising strategy to address the limitations associated with permanent synthetic meshes, particularly the risk of mesh-related complications and long-term morbidity. Recent studies have demonstrated that PhasixST™ mesh, composed of poly-4-hydroxybutyrate (P4HB), is slowly absorbed over 12 to 18 months, providing a scaffold that supports native tissue integration and healing during the critical postoperative period. This gradual absorption profile may confer an advantage over more rapidly degrading bioabsorbable meshes, as it allows for more robust tissue ingrowth and potentially enhances the durability of hiatal reinforcement. The association between P4HB mesh use and low recurrence rates has been highlighted, with an average of 2.82 hernia recurrences per 100 patients within one year, and no mesh-related complications in the current literature. The surgical technique for PhasixST™ mesh placement involves meticulous crural reinforcement, with careful attention to mesh orientation and fixation to minimize the risk of migration or erosion. The primary objective is to restore the anatomical integrity of the hiatus, reduce the size of the defect, and prevent recurrence, while minimizing perioperative morbidity. Full article

The non-degradable polymers used in daily and commercial application are generally inexpensive; however, their excessive use leads to extensive environmental damage. In light of this, the demand for bio-derived, biocompatible, and biodegradable polymers increases since these materials are potential alternatives to petroleum-derived polymers. Polyhydroxybutyrate (PHB), a class of highly crystalline thermoplastics derived from natural sources, offer significant environmental advantages over fossil fuel-based polymers due to their inherent biodegradability. This eco-friendly profile has spurred research into their commercial applications, ranging from food packaging to pharmaceuticals. However, processing challenges, particularly for polyhydroxybutyrate (PHB)—including high costs and the requirement for elevated temperatures—remain major obstacles. Additionally, PHB-based products are often brittle and exhibit inferior mechanical properties compared to conventional petroleum-based polymers such as polypropylene and polyethylene. This review comprehensively examines the state-of-the-art processing techniques for PHB and their composites. Key properties, such as mechanical performance, thermal behavior, and degradation characteristics, are scrutinized. Furthermore, the review explores mitigation strategies, such as blending and plasticization, aimed at overcoming the mechanical brittleness while upholding the principles of sustainability and maintaining a low carbon footprint. Full article

One of the current and serious environmental problems is the pollution due to microplastics. There is an urgent need for biodegradable and bio-based materials for numerous applications, including food packaging. In this work we examine the bio-based polyester cutin for its potential to be used as food packaging material, in terms of migration, based on the Hansen Solubility Parameters (HSP). Cutin is a cross-linked polymer that is swelled by various solvents. We use the degree of swelling of cutin in carefully selected solvents of various polarities in order to estimate the HSP of cutin. Some solvents can induce alteration of the chemical structure of cutin, as proven by Fourier Transform Infrared (FTIR) measurements. This interferes with the process of estimation of the HSP and is discussed in depth. The distance R_a and the Relative Energy Difference (RED) between the HSP of cutin and various food components are calculated and used to predict the existence of favorable interactions between cutin and the food components, which is translated to a high probability for the existence of migration and permeation. Experimental confirmation of one prediction based on HSP is provided by UV-VIS photometry. Similar calculations were performed for other polyesters (poly(lactic acid) and poly(hydroxy butyrate)). Cutin exhibits compatibility with substances of low polarity, such as fats and lipids and non-polar compounds found in essential oils. Thus, migration into fatty foods is expected as well as sorption and permeation of some (volatile) compounds into cutin. Nevertheless, we conclude that the overall migration risk for cutin is lower than the one of other bio-based polyesters. HSP can be used for initial screening of potential migration risks; however, further research is necessary in order to assess the occurrence, extent, and significance of the actual migration. Full article

Footwear is traditionally manufactured using non-biodegradable polymers and leather, raising well-documented environmental and health concerns related to their production and disposal. This study explores polyhydroxyalkanoates (PHAs) as sustainable alternatives for bio-based footwear components. A stable aqueous suspension of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) was successfully formulated and applied to cotton fabrics via knife-coating. Various formulations, with and without additives and employing natural or synthetic thickeners, were evaluated in terms of surface morphology, wettability, permeability, and durability. The 10% PHBHHx formulation provided the best balance between material efficiency, coating uniformity, and surface performance. Additives and thermal treatment both influenced wettability, reducing contact angles and enhancing water vapor permeability. Notably, coatings with additives and hot pressing exhibited the highest permeability (68.0 ± 3.1 L/m²/s; 651.0 ± 5.4 g/m²/24 h), while additive-free, non-pressed coatings showed significantly lower values (19.5 ± 4.4 L/m²/s; 245.6 ± 66.2 g/m²/24 h), likely due to excessive compaction. Abrasion resistance remained excellent across all samples, especially with thermal treatment, withstanding 51,200 cycles. Washing resistance results revealed a synergistic effect between additives and heat, promoting long-term hydrophobicity and coating adhesion. Overall, PHBHHx coatings demonstrated potential to enhance water resistance while maintaining breathability, representing a sustainable and effective solution for functional and technical footwear applications. Full article

Developing sustainable textile finishes that enhance moisture management and breathability remains a significant challenge in designing high-performance apparel. In this study, we propose an eco-friendly coating strategy utilizing an aqueous dispersion of poly(3-hydroxybutyrate)-diol (PHB.E.0), a member of the polyhydroxyalkanoate (PHA) family. This coating was applied to woven polyester (PES) and cotton (CO) fabrics using a low-impact spray-coating technique, aiming to improve functional properties while maintaining environmental sustainability. This solvent-free process significantly reduces chemical usage and energy demand, aligning with sustainable manufacturing goals. Successful deposition of the coating was confirmed by scanning electron microscopy (SEM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), elemental (C/O) analysis, and thermogravimetric analysis (TGA), which also revealed substrate-dependent thermal behaviour. Wettability, water absorption, and permeability tests showed that the coated fabrics retained their hydrophilic character. PHB.E.0 coatings led to a significant reduction in air permeability, particularly after hot pressing at 180 °C, from ≈670 to ≈171 L·m⁻² s⁻¹ for PES and from ≈50 to ≈30 L·m⁻²·s⁻¹ for CO, without compromising water vapor permeability. All coated samples maintained high breathability, essential for wearer comfort. These results demonstrate that PHB.E.0 coatings enhance wind resistance while preserving moisture vapor transport, offering a sustainable and effective solution for functional sportswear. Full article

This study examines binary blends of three types of polyhydroxyalkanoates (PHAs)—poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB)—with a focus on their rheological, thermal, and mechanical behavior. The blends exhibit partial miscibility in both the melt and solid states. Glass transition analysis revealed that semicrystalline/amorphous PHA combinations are fully miscible (single Tg) at amorphous PHA contents below 30 wt%. Above this threshold, a two-phase morphology develops, consisting of crystalline spherulites embedded in an amorphous matrix. When the amorphous PHA content reached ≥30 wt%, the blends could be oriented by stretching, yielding materials that display thermoplastic elastomer (TPE)-like behavior without chemical modification of the base polymers. Thermal and mechanical characterization, supported by X-ray diffraction of samples before and after orientation, confirmed that the elastomeric properties originate from the multiphase architecture formed by crystalline and amorphous domains interconnected through a miscible amorphous fraction. Full article

To combat the growing issue of petroleum plastic waste, alternative bio-based polymers are being developed. Many of these biopolymers are made from bio-derived materials, or are biodegradable, but the most promising polymers fall in both categories. Polyhydroxyalkanoates (PHAs) are one such class of polymers, and poly-3-hydroxybutyrate (P3HB), the most popular PHA, has shown great potential. This study utilized two types of cotton-derived glucose, alongside commercial glucose, as a feedstock for the biosynthesis of P3HB by Cupriavidus necator (also known as Ralstonia eutropha). The fermentation took place in a 2-L bioreactor, showing potential for scale-up. A single-solvent extraction method was created and utilized to reduce process complexity and chemical consumption of the polymer extraction. Both cotton-derived glucoses were shown to produce more P3HB than commercial glucose. The resulting P3HB samples were compared to each other and to the literature based on polymer yield and thermal characteristics. While all samples averaged a smaller yield than seen in the literature (indicating the need for optimization of the bacterial growth and metabolism with a growth curve in our future work), the cotton-derived glucose was shown to yield more P3HB than commercial glucose. Further, cotton-derived P3HB had very similar thermal properties to the commercial glucose-derived P3HB (and to values from the literature) with onset of thermal degradation ranging from 185 °C to 263 °C, cold crystallization temperatures ranging from 24 °C to 28 °C, and melting temperatures ranging from 147 °C to 151 °C. Lastly, all samples were shown to have a similar percentage crystallinity, ranging from 38% to 45%, which is slightly lower than that reported in the literature. P3HB made from cotton-derived glucose was shown to have potential as a scalable, sustainable alternative process. Full article

This study investigates the air filtration capabilities of fibrous membranes fabricated via electrospinning, with a focus on optimizing processing parameters. Specifically, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a well-characterized biodegradable polyester, was electrospun to produce membranes exhibiting precisely controlled surface microstructures. The optimal fiber morphology was attained under conditions of a 20 kV applied electric field, a solution flow rate of 0.5 mL·h⁻¹, a polymer concentration of 13 wt.%, and a needle inner diameter of 0.21 mm. The microstructural features of the electrospun PHBV membranes were characterized using scanning electron microscopy (SEM). Complementary analysis via ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed that the membranes comprised pure 3-hydroxyvalerate (3HV) copolymerized with 3-hydroxybutyrate (3HB) terminal units, with 3HV mole fractions ranging from 17% to 50%. The incorporation of different molar percentages of 3HV in PHBV membrane significantly enhances its durability, as evidenced by Ball Burst Strength (BBS) measurements, with an elongation at burst that is 65–86% greater than that of ASTM F2100 level 3 mask. The nanofibrous membranes exhibited a controlled pore size distribution, indicating their potential suitability for air filtration applications. Particle filtration efficiency (PFE) assessments under standard atmospheric pressure conditions showed that the optimized electrospun PHBV membranes achieved filtration efficiencies exceeding 98%. Additionally, the influence of 3HV content on biodegradation behavior was evaluated through soil burial tests conducted over 90 days. Results indicated that membranes with lower 3HV content (17 mol.%) experienced the greatest weight loss, suggesting accelerated degradation in natural soil environments. Full article

In the context of the urgent global transition toward sustainable materials, this study presents a comparative environmental life cycle assessment (LCA) of poly(3-hydroxybutyrate) (PHB), a biodegradable, bio-based polymer, against conventional petrochemical plastics (polystyrene—PS; polypropylene—PP) and another popular biopolymer, namely polylactic acid (PLA). The LCA was conducted using primary production data from a laboratory-scale PHB manufacturing process, integrating real-time energy consumption measurements across all production stages. Environmental indicators such as carbon footprint and energy demand were analyzed under cradle-to-gate and end-of-life scenarios. The results indicate that PHB, while offering biodegradability and renewable sourcing, currently exhibits a significantly higher carbon footprint than PP, PS, and PLA, primarily due to its energy-intensive downstream processing. However, the environmental impact of PHB can be markedly reduced—by over 67%—through partial integration of renewable energy. PLA demonstrated the lowest production-phase emissions, while PP showed the most favorable end-of-life outcomes under municipal waste management assumptions. The study highlights the critical influence of energy sourcing, production scale, and waste treatment infrastructure on the sustainability performance of biopolymers. These findings provide practical insights for industry and policymakers aiming to reduce the environmental burden of plastics and support a shift toward circular material systems. Full article

Poly(3-hydroxybutyrate), P3HB, is a biodegradable polymer produced and stored by different bacterial strains, including Ralstonia eutropha H16. P3HB was used to prepare biocompatible composites modified by nanocellulose. This study aimed to assess selected thermal, mechanical, and biological properties of the obtained nanobiocomposites. Thermal properties, as determined by differential scanning calorimetry measurements, were established. The crystallinity of nanocomposites and polymeric matrix was investigated using DSC analyses. The morphology of the nanocomposites was evaluated using scanning electron microscopy. The Food and Drug Administration and the European Medicines Agency confirmed the immunosafety of the tested nanocomposites and noted they had either no or very low levels of endotoxin contamination. Some mechanical properties of the investigated materials were also measured and are presented here. It was estimated that the addition of 1% by mass of nanocrystalline cellulose to P3HB causes the greatest improvement in the plasticization of the material, characterised by the best processing and utility properties. The processing window of nanobiocomposites was extended by approximately 25 °C in reference to the unfilled poly(3-hydroxybutyrate). Mechanical and thermal tests revealed that the most desirable properties oscillate around the addition of 0.5% and 1% nanocrystalline cellulose by mass in the nanobiocomposites. Biological studies on implant applications have shown that the addition of only 0.5% nanofiller to a nanobiocomposite can be of key importance. Full article

Marine Bacteroidota are recognized bacterial producers of bioactive metabolites, yet their biosynthetic potential remains cryptic under standard laboratory conditions. Here, we developed chemically defined media for Fulvivirga kasyanovii 48LL (Cytophagia) and Tenacibaculum mesophilum fLL (Flavobacteriia) to evaluate the effect of environmentally relevant carbon sources on growth and secondary metabolism. F. kasyanovii utilized 31 of 34 tested carbon sources whereas T. mesophilum grew on only five substrates, underscoring a distinct nutritional preferences. Substrate significantly influenced the antibacterial activity of F. kasyanovii extracts. Growth on β-1,3-glucan, glycerol, poly(β-hydroxybutyrate) (PHB), fish gelatin, or pectin resulted in extracts generating the largest inhibition zones (10–13 mm) against Bacillus subtilis or Rossellomorea marisflavi. Genome analysis revealed F. kasyanovii to be enriched in biosynthetic gene clusters (BGCs), notably harboring a ~570 kb genomic island comprising five large NRPS/PKS-type clusters. Quantitative PCR confirmed carbon-source-dependent regulation of these operons: glucose induced BGC1, BGC3, and BGC4, while κ-carrageenan and PHB upregulated BGC2. Conversely, yeast–peptone medium (analogous to standard marine broth) repressed transcription across all active clusters. These findings demonstrate that naturally occurring carbon sources can selectively activate cryptic BGCs and modulate antibacterial activity in F. kasyanovii, suggesting that similar strategy can be used for natural-product discovery in marine Bacteroidota. Full article