Search Results (218)

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

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

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

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

P(3HB) is a biodegradable and biocompatible polymer, which can replace petroleum-derived plastics. Previous studies have shown that Azotobacter vinelandii strain OP-PhbP3⁺, which overexpresses the phasin protein PhbP3, produces high concentrations of P(3HB) and undergoes early autolysis, facilitating polymer release. The aim of the present study was to evaluate the performance of this strain for P(3HB) production in 3 L bioreactors and assess the feasibility of a simplified recovery process. After 36 h of cultivation, rapid cell lysis was observed, resulting in a ~50% decrease in the protein content of the cell dry weight, without reducing P(3HB) concentration, which reached 4.6 g L⁻¹. Flow cytometry analysis revealed significant morphological changes during cultivation, which was consistent with the strain’s lytic behavior. The biomass recovered at 36 h was washed with SDS, obtaining a yield of 92.5% (respect to P(3HB) initial) and a purity of 97.6%. An alternative extraction procedure using the non-halogenated solvent cyclohexanone (CYC) resulted in an even higher yield of 97.8% with a purity of 99.3% of P(3HB). Notably, the weight average molecular weight of the polymer remained stable at 8000 kDa during the entire process. Overall, the combination of PhbP3 over-expression and environmentally friendly solvents, such as CYC, enabled efficient P(3HB) production with high yield and purity while preserving polymer quality. Full article

Biocompatible nanofibrous dressings integrating bioactive compounds with antioxidative and antimicrobial properties offer a promising solution for effective wound healing. In the presented study, we developed a novel dual-delivery system by combining forcespun nanofibres with poly(3-hydroxybutyrate) (PHB)-liposomes to enhance bioavailability and enable targeted release of bioactive agents (eugenol, thymol, curcumin, ampicillin, streptomycin, gentamicin). These agents exhibited notable antioxidant activity (2.27–2.33 mmol TE/g) and synergistic or partially synergistic antimicrobial effects against E. coli, M. luteus, S. epidermidis, and P. aeruginosa ( Fractional Inhibitory Concentration index 0.09–0.73). The most potent combinations, particularly thymol, eugenol, and ampicillin, were encapsulated in the nanofibre–liposomal matrix. The successful preparation of a new combined delivery system was confirmed by structural analysis using Electron and Fluorescence Microscopy. The dual-composite materials retained the antimicrobial properties of the individual compounds upon release, with the highest increases of ~73.56% against S. epidermidis. Cell viability and in vitro immunology assays using the human keratinocyte cell line (HaCaT) showed a slight decrease in viability and immune response stimulation, while not impairing wound re-epithelisation. These findings highlight the potential of firstly reported novel carrier utilising both PHB-nanofibres and PHB-liposomes, exhibiting simultaneous antioxidant and antimicrobial activity as promising candidates for the treatment of infected wounds under oxidative stress. Full article

This work is devoted to the electrospinning of biocompatible fibrous matrixes for microbial wound therapy. The problem of treating staphylococcal-infected wounds remains urgent. In this study, we propose a new approach to the use of the chlorophyll (Chl) and poly-3-hydroxybutyrate (PHB) composite system in the treatment of infected wounds. The structure and properties of the electrospun polymer matrix based on PHB modified with various concentrations of Chl was investigated by SEM, confocal microscopy, DSC, EPR. The release rate, fluorescence, and antimicrobial activity of Chl incorporated into PHB were studied. The high efficiency of the developed materials was shown with the participation of laboratory animals. Full article

The environmental burden of conventional plastics has sparked interest in sustainable alternatives such as polyhydroxyalkanoates (PHAs). However, despite ample research in bioprocess development and the use of inexpensive waste streams, production costs remain a barrier to widespread commercialization. Complementary to this, genetic engineering offers another avenue for improved productivity. Cupriavidus necator stands out as a model host for PHA production due to its substrate flexibility, high intracellular polymer accumulation, and tractability to genetic modification. This review delves into metabolic engineering strategies that have been developed to enhance the production of poly(3-hydroxybutyrate) (PHB) and related copolymers in C. necator. Strategies include the optimization of central carbon flux, redox and cofactor balancing, adaptation to oxygen-limiting conditions, and fine-tuning of granule-associated protein expression and the regulatory network. This is followed by outlining engineered pathways improving the synthesis of PHB copolymers, PHBV, PHBHHx, and other emerging variants, emphasizing genetic modifications enabling biosynthesis based on unrelated single-carbon sources. Among these, enzyme engineering strategies and the establishment of novel artificial pathways are widely discussed. In particular, this review offers a comprehensive overview of promising engineering strategies, serving as a resource for future strain development and positioning C. necator as a valuable microbial chassis for biopolymer production at an industrial scale. Full article

The synthesis of bioplastics from renewable resources is essential for green living. PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is a biodegradable and biocompatible material ideal for various industrial applications. The impact of levulinic (LA), valeric acids (VA), and sodium propionate (SPr) as co-substrates in biomass and the synthesis of 3-hydroxy valerate (3HV) and co-polymerization of PHBV by Burkholderia thailandensis E264 (BtE264) was assessed. Thermogravimetric, XRD, NMR, and mechanical characterization were performed on the homopolymer (PHB) and co-polymer (PHBV), and compared to the PHBV-STD. BtE264 produced the co-polymer PHBV when adding any of the three co-substrates. LA showed a higher positive effect on microbial growth (8.4 g∙L⁻¹) and PHBV production (3.91 g∙L⁻¹), representing 78 and 22 mol % of 3HB and 3HV, respectively. The PHBV obtained with LA had a melting temperature (Tm) lower than the PHB homopolymer and presented lower values for melting enthalpies (ΔHf); the degree of crystallization and TGA values indicated that PHBV had better thermal stability. Additionally, FTIR and NMR revealed that BtE264 synthesizes PHBV with an organization in monomeric units (3HB-3HV), suggesting differentiated incorporation of the monomers, improving 3.4 times the break elongation the co-polymer’s tensile properties. This study highlights the co-substrates’ relevance in PHBV synthesis using BtE264 for the first time. Full article

Engineering of Cupriavidus necator could enable the production of various polyhydroxyalkanoates (PHAs); particularly, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HH)), a biopolymer with enhanced mechanical and thermal properties compared to poly(3-hydroxybutyrate) (PHB), can be efficiently produced from vegetable oils. However, challenges remain in the recovery process, particularly in removing residual oil and minimizing degradation of the polymer structure during extraction steps. This study investigated the effects of ethanol-based defatting on the recovery and polymeric properties of P(3HB-co-3HH). The proposed method involves the addition of ethanol to the cell broth to effectively remove residual oil. Ethanol improved the separation of microbial cells from the broth, thereby streamlining the downstream recovery process. Using ethanol in the washing step increased the recovery yield and purity to 95.7% and 83.4%, respectively (compared to 87.4% and 76.2% for distilled water washing), representing improvements of 8.3% and 7.2%. Ethanol washing also resulted in a 19% higher molecular weight compared to water washing, indicating reduced polymer degradation. In terms of physical properties, the elongation at break showed a significant difference: 241.9 ± 27.0% with ethanol washing compared to water (177.7 ± 10.3%), indicating ethanol washing retains flexibility. Overall, an ethanol washing step for defatting could simplify the recovery steps, increase yield and purity, and retain mechanical properties, especially for P(3HB-co-3HH) from oils. Full article

In recent years, membranes have found extensive applications, primarily in wastewater purification and food packaging. However, petroleum-based membranes can be detrimental to the environment. For this reason, extensive studies are being conducted to identify environmentally friendly substitutes for the materials used in membrane composition. Among these materials, polylactic acid (PLA) and poly(3-hydroxybutyrate) (PHB) are two bio-sourced and biodegradable polymers that can be derived from lignocellulosic waste. These polymers also possess suitable characteristics, such as thermal resistance and mechanical strength, which make them potential candidates for replacing conventional plastics. This study provides an overview of recent advances in the production of PLA and PHB, with a focus on their extraction from lignocellulosic biomass, as well as the recent applications of these two biodegradable polymers as sustainable materials in membrane manufacturing. The advantages and limitations of membranes produced from these materials are also summarized. Lastly, an analysis of future trends is provided concerning new sources, production possibilities, and potential applications in water treatment (mainly for metal ions separation), gas separation, oil–water separation, medical applications, drug release control, and food packaging. Full article

Multi-layer cell constructs produced in vitro are an innovative treatment option to support the growing demand for therapy in regenerative medicine. Our research introduces a novel construct integrating organ-derived decellularised extracellular matrix (dECM) hydrogels and 3D-printed biodegradable polymer meshes composed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) to support and maintain multiple layers of different cell types. We achieved that by integrating the mechanical stability of PHBV+P34HB, commonly used in the food storage industry, with a dECM hydrogel, which replicates organ stiffness and supports cellular survival and function. The construct was customised by adjusting the fibre arrangement and pore sizes, making it a suitable candidate for a personalised design. We showed that the polymer is degradable after precoating it with PHB depolymerase (PhaZ), with complete degradation achieved in 3–5 days and delayed by adding the hydrogel to 10 days, enabling tuneable degradation for regenerative medicine applications. Finally, as a proof of concept, we composed a three-layered tissue in vitro; each layer represented a different tissue type: epidermal, vascular, and subcutaneous layers. Possible future applications include wound healing and diabetic ulcer paths, personalised drug delivery systems, and personalised tissue implants. Full article

Ultrafine fibers from poly(3-hydroxybutyrate) (PHB) and polyvinylpyrrolidone (PVP) and their blends with different component ratios in the range of 0/100 to 100/0 wt.% were obtained, and their structure and dynamic properties were studied. The polymers were obtained via electrospinning in solution mode. The structure, morphology, and segmental dynamic behavior of the fibers were determined using optical microscopy, SEM, EPR, DSC, and IR spectroscopy. The low-temperature maximum on the DSC endotherms provided information on the state of the PVP hydrogen bond network, which made it possible to determine the enthalpies of thermal destruction of these bonds. The PHB/PVP fiber blend ratio significantly affected the structural and dynamic parameters of the system. Thus, at low concentrations of PVP (up to 9%) in the structure of ultra-fine fibers, the distribution of this polymer occurs in the form of tiny particles, which are crystallization centers, which causes a significant increase in the degree of crystallinity (χ) activation energy (E_act) and slowing down of molecular dynamics (τ). At higher concentrations of PVP, loose interphase layers were formed in the system, which caused a decrease in these parameters. The strongest changes in the concentration of hydrogen bonds occurred when PVP was added to the composition from 17 to 50%, which was due to the formation of intermolecular hydrogen bonds both in PVP and during the interaction of PVP and PHB. The diffusion coefficient of water vapor in the studied systems (D) decreased as the concentration of glassy PVP in the composition increased. The concentration of the radical decreased with an increase in the proportion of PVP, which can be explained by the glassy state of this polymer at room temperature. A characteristic point of the 50/50% mixture component ratio was found in the region where an inversion transition of PHB from a dispersion material to a dispersed medium was assumed. The conducted studies made it possible for the first time to conduct a comprehensive analysis of the effect of the component ratio on the structural and dynamic characteristics of the PHB/PVP fibrous material at the molecular scale. Full article

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)) is a representative PHA copolymer that can improve the mechanical limitations of polyhydroxybutyrate (P(3HB)). Although genetic engineering can facilitate 3HHx incorporation, it often compromises cell growth and reduces polymer molecular weight owing to metabolic disruptions caused by the deletion of acetoacetyl coenzyme A (acetyl-CoA) reductase (PhaB). To address this issue, native strains capable of producing high levels of 3HHx were identified via oil-based Cupriavidus screening. Eight PHA-producing strains were isolated from various samples and Cupriavidus sp. Oh_1 exhibited the highest polyhydroxybutyrate (PHB) production at 15.23 g/L from 17.2 g/L of biomass using soybean oil. Moreover, Oh_1/phaC_RaJ_Pa, containing enoyl-CoA hydratase (phaJ) and PHA synthetase (phaC), was identified as the most effective novel strain producing the highest 3HHx mole fraction, 48.93 g/L of PHA from 52.3 g/L of biomass and achieving a maximum 3HHx accumulation of 27.2 mol%. The resulting P(3HB-co-3HHx) showed a higher Mw (12.3 × 10⁵) compared with P(3HB-co-3HHx) produced by the phaB-deleted strain (14.6 × 10⁴). Higher production of 3HHx was attributed to the higher expression of phaC_Ra and phaJ_Pa in Oh_1, with log2 fold changes of 2.94 and 8.2, respectively, as well as the upregulation of certain β-oxidation encoding operons. Collectively, these findings highlight a strain capable of synthesizing a substantial 3HHx fraction without requiring gene deletions or extensive genetic modifications. Full article