Applications Of Polyhydroxyalkanoates Research Articles

Advancing Sustainability: Utilizing Bacterial Polyhydroxyalkanoate for Food Packaging

Polyhydroxyalkanoates (PHAs) are promising biodegradable polymers known for their biodegradability and eco-friendly properties. Recent studies indicate that PHAs can reduce the environmental impact by up to 50% compared to petroleum-based plastics. This comprehensive review evaluates the application of PHAs in sustainable food packaging, covering over 100 studies published between 2018 and 2023. The review highlights advancements in PHA production, with a focus on submerged and solid-state fermentation methods, achieving up to a 60% improvement in production efficiency through optimized culture selection. Sustainable extraction and purification methods have been identified, reducing energy consumption by 30%. Blending PHAs with other biodegradable polymers like polylactic acid, starch, and cellulose enhances material performance, with up to a 40% improvement in mechanical properties. The incorporation of antimicrobial agents and essential oils has been shown to extend the shelf life by 25% while maintaining food safety standards. This review underscores the potential of active PHA-based packaging in improving the barrier properties by 35% when combined with coatings, positioning PHA as a key material for the future of environmentally responsible and safe food packaging.

Elucidating regulation of polyhydroxyalkanoate metabolism in Ralstonia eutropha: Identification of transcriptional regulators from phasin and depolymerase genes

Despite the ever-growing research interest in polyhydroxyalkanoates (PHAs) as green plastic alternatives, our understanding of the regulatory mechanisms governing PHA synthesis, storage, and degradation in the model organism Ralstonia eutropha remains limited. Given its importance for central carbon metabolism, PHA homeostasis is probably controlled by a complex network of transcriptional regulators. Understanding this fine-tuning is key for developing improved PHA production strains thereby boosting the application of PHAs. We conducted promoter pull-down assays with crude protein extracts from R. eutropha Re2058/pCB113, followed by LC-MS/MS, to identify putative transcriptional regulators involved in the expression control of PHA metabolism, specifically targeting phasin phaP1 and depolymerase phaZ3 and phaZ5 genes. The impact on promoter activity was studied in vivo using β-galactosidase assays and the most promising candidates were heterologously produced in Escherichia coli and their interaction with the promoters investigated in vitro by Electrophoretic Mobility Shift Assays. We could show that R. eutropha DNA-binding XRE-family-like protein H16_B1672, specifically binds the phaP1 promoter in vitro with a KD of 175 nM and represses gene expression from this promoter in vivo. Protein H16_B1672 also showed interaction with both depolymerase promoters in vivo and in vitro suggesting a broader role in the regulation of PHA metabolism. Furthermore, in vivo assays revealed that the H-NS-like DNA-binding protein H16_B0227 and the peptidyl-prolyl cis-trans isomerase PpiB, strongly repress gene expression from PphaP1 and PphaZ3, respectively. In summary, this study provides new insights into the regulation of PHA metabolism in R. eutropha, uncovering specific interactions of novel transcriptional regulators.

Polyhydroxyalkanoates for Sustainable Aquaculture: A Review of Recent Advancements, Challenges, and Future Directions.

Polyhydroxyalkanoates (PHA) are biodegradable biopolymers produced by prokaryotic microbes, which, at the same time, can be applied as single-cell proteins (SCPs), growing on renewable waste-derived substrates. These PHA polymers have gained increasing attention as a sustainable alternative to conventional plastics. One promising application of PHA and PHA-rich SCPs lies within the aquaculture food industry, where they hold potential as feed additives, biocontrol agents against diseases, and immunostimulants. Nevertheless, the cost of PHA production and application remains high, partly due to expensive substrates for cultivating PHA-accumulating SCPs, costly sterilization, energy-intensive SCPs harvesting techniques, and toxic PHA extraction and purification processes. This review summarizes the current state of PHA production and its application in aquaculture. The structure and classification of PHA, microbial sources, cultivation substrates, biosynthesis pathways, and the production challenges and solutions are discussed. Next, the potential of PHA application in aquaculture is explored, focusing on aquaculture challenges, common and innovative PHA-integrated farming practices, and PHA mechanisms in inhibiting pathogens, enhancing the immune system, and improving growth and gut health of various aquatic species. Finally, challenges and future research needs for PHA production and application in aquaculture are identified. Overall, this review paper provides a comprehensive overview of the potential of PHA in aquaculture and highlights the need for further research in this area.

Recent Biotechnological Applications of Polyhydroxyalkanoates (PHA) in the Biomedical Sector-A Review.

Petroleum-derived plastics are materials of great importance for the contemporary lifestyle, and are widely used commercially because they are low cost, resistant, malleable, and weightless, in addition to their hydrophobic character. However, some factors that confer the qualities of these materials also cause problems, mainly environmental, associated with their use. The COVID-19 pandemic aggravated these impacts due to the high demand for personal protective equipment and the packaging sector. In this scenario, bioplastics are environmentally positive alternatives to these plastics due to their applicability in several areas ranging from packaging, to biomedicine, to agriculture. Polyhydroxyalkanoates (PHAs) are biodegradable biopolymers usually produced by microorganisms as an energy reserve. Their structural variability provides a wide range of applications, making them a viable option to replace polluting materials. PHAs can be applied in various biotechnology sectors, such as producing drug carriers and scaffolds for tissue engineering. This review aimed to survey works published in the last five years on the study and biotechnological application of PHAs in the biomedical sector, exploring the versatility and advantages of their use and helping to understand how to enhance their application.

A novel strategy for the preparation of multifunctional and robust polyhydroxyalkanoates/GQDs nanocomposites with UV-resistance, pH-responsive and antibacterial properties

Biosynthesized polyhydroxyalkanoates (PHAs) offer several compelling advantages, including biodegradability, biocompatibility, and suitability for use in environmentally friendly packaging materials. However, poor crystallization ability and lack of functionality (e.g., UV-resistance and antibacterial properties) significantly restrict the practical applications of PHAs. In this study, graphene quantum dots (GQDs) containing with rich amino groups, carboxy groups and conjugate structure were tailor-made as multifunctional nanofillers to prepare PHAs/GQDs composites. The GQDs not only exhibited excellent dispersion within the PHAs matrix at the nanoscale but also act as nucleating agents to dramatically increase the nucleation density of PHAs. Remarkably, the incorporation of just 0.5 wt% GQDs led to outstanding antibacterial performance (99.99%), UV resistance (90.50%), transparency (>80%) and mechanical properties in the PHAs composite. ​Moreover, these PHAs composites displayed strong fluorescence stability and demonstrated sensitivity to pH variations. Building upon these findings, we propose a novel concept for a wearable device capable of intelligently detecting changes in sweat pH during human exercise. This work presents a straightforward and effective method for preparing multifunctional GQDs, thereby expanding the potential applications of PHAs in the realm of green packaging and intelligent sensing.

Exploiting Polyhydroxyalkanoates for Biomedical Applications.

Polyhydroxyalkanoates (PHA) are biodegradable plastic. Numerous bacteria produce PHAs under environmental stress conditions, such as excess carbon-rich organic matter and limitations of other nutritional elements such as potassium, magnesium, oxygen, phosphorus, and nitrogen. In addition to having physicochemical properties similar to fossil-fuel-based plastics, PHAs have unique features that make them ideal for medical devices, such as easy sterilization without damaging the material itself and easy dissolution following use. PHAs can replace traditional plastic materials used in the biomedical sector. PHAs can be used in a variety of biomedical applications, including medical devices, implants, drug delivery devices, wound dressings, artificial ligaments and tendons, and bone grafts. Unlike plastics, PHAs are not manufactured from petroleum products or fossil fuels and are, therefore, environment-friendly. In this review, a recent overview of applications of PHAs with special emphasis on biomedical sectors, including drug delivery, wound healing, tissue engineering, and biocontrols, are discussed.

Recent advances of medical polyhydroxyalkanoates in musculoskeletal system.

Infection and rejection in musculoskeletal trauma often pose challenges for natural healing, prompting the exploration of biomimetic organ and tissue transplantation as a common alternative solution. Polyhydroxyalkanoates (PHAs) are a large family of biopolyesters synthesised in microorganism, demonstrating excellent biocompatibility and controllable biodegradability for tissue remodelling and drug delivery. With different monomer-combination and polymer-types, multi-mechanical properties of PHAs making them have great application prospects in medical devices with stretching, compression, twist in long time, especially in musculoskeletal tissue engineering. This review systematically summarises the applications of PHAs in multiple tissues repair and drug release, encompassing areas such as bone, cartilage, joint, skin, tendons, ligament, cardiovascular tissue, and nervous tissue. It also discusses challenges encountered in their application, including high production costs, potential cytotoxicity, and uncontrollable particle size distribution. In conclusion, PHAs offer a compelling avenue for musculoskeletal system applications, striking a balance between biocompatibility and mechanical performance. However, addressing challenges in their production and application requires further research to unleash their full potential in tackling the complexities of musculoskeletal regeneration.

Microbial Production of Bioplastics: An Eco-friendly Alternative

Accumulation of non-biodegradable plastic has shown adverse impacts on the environment and calls for a dire need for a sustainable alternative. Various microbial strains can produce bioplastics in the form of Polyhydroxyalkanoates (PHAs) as energy reserves. Many bacteria, fungi and microalgae have been studied to produce such biopolymers. PHAs are biodegradable and meet the basic requirements of life cycle environmental impact or life cycle assessments for proper disposal. They are also biocompatible and renewable. They have high Elastic modulus, Tensile modulus, melting temperature, and crystallinity with many other properties similar to synthetic plastics currently in use, making them a more reliable and sustainable substitute. Bioplastics produced from PHAs have found a myriad of applications in medicine, pharmaceuticals, agriculture and the packaging industry. This review emphasizes the structure of PHAs, their biosynthesis and relevant microbial strains employed, including genetically engineered strains, microbes from extreme niches and mixed microbial cultures. It focuses on using cheap and sustainable carbon feedstocks, including agricultural residues, lignocellulosic biomass and crude glycerol, on making the production of PHAs cleaner and commercially feasible. Industrially scaled production using different fermentation strategies, downstream processing and purification, along with the wide range of applications of PHAs, is also discussed.

Potential of polyhydroxyalkanoate and nanocellulose from oil palm trunk as raw materials for additive manufacturing: A review

AbstractAdditive manufacturing (AM) is beneficial due to its fast prototyping, non‐complexity process, flexibility, which allows for a wide range of innovations. The AM presented in this review concentrated solely on the fused deposition modeling method. The application of polyhydroxyalkanoate (PHA) biopolymer in conjunction with AM technology in accordance with the interest of researchers in practicing sustainable development. Most studies discovered that the features of PHA, such as its brittleness, slow crystallization, and small processing window, may be overcome by blending it with other polymers. In particular, the physical and chemical properties of PHA have a strong influence on its printability in three‐dimensional printing. Furthermore, this article discussed the use of nanocellulose as a reinforcing material in PHA blends due to its high‐surface area, lightweight, and excellent biocompatibility. The limitations in creating and applying PHA were also highlighted, as it was expensive and difficult to process at high temperatures. Overall, this article provided an overview of AM, including the potential of oil palm trunk as a source of PHA and nanocellulose for bio‐composite products.

Beta-tricalcium phosphate enhanced mechanical and biological properties of 3D-printed polyhydroxyalkanoates scaffold for bone tissue engineering

Polyhydroxyalkanoates (PHA) is a naturally degradable polyester with good biocompatibility. However, several disadvantages including poor bioactivity and mechanical properties limit the biomedical application of PHA. To circumvent these drawbacks, PHA needs to be blended with other materials to improve performance. Beta-tricalcium phosphate (β-TCP) has emerged as one of the most promising bone repair materials due to its good biocompatibility, satisfactory mechanical properties, and excellent bone osteoconductivity. In this study, PHA filled with β-TCP in 0 wt%, 5 wt%, 10 wt%, 20 wt%, and 30 wt% of concentrations were produced using a twin-screw extruder. The extruded 3D filaments made with 20% β-TCP exhibited the maximum mechanical properties to manufacture 3D scaffolds for bone tissue engineering. We then prepared the 3D-printed PHA/β-TCP scaffolds by using the fused deposition modeling (FDM) technique. The compressive strength and the shore hardness of the PHA/20%β-TCP scaffold were 36.7 MPa and 81.1 HD. The produced scaffolds presented compressive strength compatible with natural bone. In addition, the scaffolds with a well-controlled design of pore shape and size provided sufficient space for cellular activity. In vitro studies demonstrated that the addition of β-TCP could significantly improve the proliferation, adhesion, and migration of MC3T3-E1 cells in the PHA/β-TCP scaffold. Moreover, the osteogenesis-related genes expression of the PHA/β-TCP scaffold was enhanced compared to the PHA scaffolds. Therefore, the 3D-printed PHA/β-TCP scaffold represents an effective strategy to promote mechanical and biological properties, showing huge potential for bone tissue engineering applications.

Polyhydroxyalkanoates in tissue repair and regeneration

Developing advanced biocompatibility materials is of critical importance in biomedical engineering. Polyhydroxyalkanoates (PHA), being famous for its flexible mechanical properties, thermal properties, biocompatibility, and biodegradability, has been widely used in wound dressings, artificial blood vessels, heart valves, nerve conduits, bone and cartilage scaffolds, surgical sutures, and other fields. However, reports on the application of PHA in tissue repair and regeneration are often lacking in systematics. Here, a comprehensive and in-depth perception of the performance advantages and application value of PHA is provided. In this review, the following applications of PHA in biomedical engineering are covered: i) soft tissue, ii) organ tissue, iii) vascular tissue, iv) heart valve tissue, v) nerve conduit tissue, vi) bone tissue, vii) cartilage tissue and viii) others. Finally, an outlook on the future research directions and challenges of PHA is presented.

The Synthesis, Characterization and Applications of Polyhydroxyalkanoates (PHAs) and PHA-Based Nanoparticles.

Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.

A Review of the Applications and Biodegradation of Polyhydroxyalkanoates and Poly(lactic acid) and Its Composites.

Overconsumption of plastic goods and improper handling of petroleum-derived plastic waste have brought a plethora of negative impacts to the environment, ecosystem and human health due to its recalcitrance to degradation. These drawbacks become the main driving force behind finding biopolymers with the degradable properties. With the advancement in biopolymer research, polyhydroxyalkanoate (PHA) and poly(lacyic acid) (PLA) and its composites have been alluded to as a potential alternative to replace the petrochemical counterpart. This review highlights the current synthesis process and application of PHAs and PLA and its composites for food packaging materials and coatings. These biopolymers can be further ameliorated to enhance their applicability and are discussed by including the current commercially available packaging products. Factors influencing biodegradation are outlined in the latter part of this review. The main aim of this review article is to organize the scattered available information on various aspects of PHAs and PLA, and its composites for packaging application purposes. It is evident from a literature survey of about 140 recently published papers from the past 15 years that PLA and PHA show excellent physical properties as potential food packaging materials.

Multifunctional Biocomposites Based on Polyhydroxyalkanoate and Graphene/Carbon Nanofiber Hybrids for Electrical and Thermal Applications

Most polymers are long-lasting and produced from monomers derived from fossil fuel sources. Bio-based and/or biodegradable plastics have been proposed as a sustainable alternative. Amongst those available, polyhydroxyalkanoate (PHA) shows great potential across a large variety of applications but is currently limited to packaging, cosmetics and tissue engineering due to its relatively poor physical properties. An expansion of its uses can be accomplished by developing nanocomposites where PHAs are used as the polymer matrix. Herein, a PHA biopolyester was melt blended with graphene nanoplatelets (GNPs) or with a 1:1 hybrid mixture of GNPs and carbon nanofibers (CNFs). The resulting nanocomposites exhibited enhanced thermal stability while their Young's modulus roughly doubled compared to pure PHA. The hybrid nanocomposites percolated electrically at lower nanofiller loadings compared to the GNP-PHA system. The electrical conductivity at 15 wt.% loading was ~ 6 times higher than the GNP-based sample. As a result, the electromagnetic interference shielding performance of the hybrid material was around 50% better than the pure GNPs nanocomposites, exhibiting shielding effectiveness above 20 dB, which is the threshold for common commercial applications. The thermal conductivity increased significantly for both types of bio-nanocomposites and reached values around 5 W K-1 m-1 with the hybrid-based material displaying the best performance. Considering the solvent-free and industrially compatible production method, the proposed multifunctional materials are promising to expand the range of application of PHAs and increase the environmental sustainability of the plastic and plastic electronics industry.

Poly‐3‐hydroxybutyrate‐based constructs with novel characteristics for drug delivery and tissue engineering applications—A review

AbstractHerein, we reviewed polymeric constructs of polyhydroxyalkanoates (PHAs) at large and poly‐3‐hydroxybutyrate (P3HB), in particular, for drug delivery and tissue engineering applications. Polymeric constructs that can efficiently respond to numerous variations in their surroundings have gained notable attention from different industrial sectors such as biomedical, clinical, pharmaceutical, and cosmeceutical. Among them, considerable importance is given to their drug delivery and tissue engineering applications. PHAs with peculiar reference to P3HB are gaining prominence attention as candidate materials with such requisite potentialities. The unique structural and functional characteristics of PHAs and P3HB are of supreme interest and being used to engineer novel constructs for efficient drug delivery and tissue regeneration purposes. So far, an array of methodological approaches, such as in vitro, in vivo, and ex vivo techniques have been exploited though using different materials with different geometries for a said purpose. However, a low‐level production majorly limits their proper exploitation. Various physiochemical characteristics and production strategies have been introduced in this review. The data have been summarized on PHAs production by several microorganisms aiming to cover the scope of the last 10 years. The present review highlights the recent applications of PHAs and P3HB‐based constructs, such as micro/nanoparticles, biocomposite, nanofibers, and hydrogels as novel drug carries for regenerative medicine and tissue engineering. In summary, drug delivery and tissue engineering potentialities of PHAs and P3HB‐based constructs are discussed with suitable examples and envisioned directions of future developments.

Microbial Polyhydroxyalkanoates (PHAs): Efficient Replacement of Synthetic Polymers

Microbial polyhydroxyalkanoates (PHAs) are biopolyesters produced by microorganisms as intracellular granules under nutrient stress. Due to non-toxic and biodegradable behavior these polyesters are a sustainable source of wide range of biomaterials such as bioplastics. As a result of excellent polymeric properties such as melting temperatures (Tm), glass transition temperature (Tg), crystallinity, Young’s modulus and stress to break ratio these polyesters are capable of replacing the synthetic plastics. Bioplastics produced using PHAs as biomass source can be used for packaging material and disposable products on the other hand biofuels can also be generated using PHAs. PHAs find countless applications in industry, agriculture, pharmaceuticals and health. A large number of bacterial, microalgal and fungal species can produce these polyesters. Bacterial species such as Bacillus megaterium, Pseudomonas aeruginosa, P. oleovorans, P. stutzeri and Cupriavidus necator are some highly studied microorganisms for PHA production. This review summarizes the most important aspects of PHAs, crystalline and granular structure of PHA biosynthesizing genes and their relevant proteins. Thermal and physical properties, sources, extraction, purification methods of PHAs are briefly discussed. Applications of PHAs, phylogenetic analysis of Pseudomonas sp. in term of its PHAs synthesizing genes, future prospects and possible outcomes are discussed.

Research progress in polyhydroxyalkanoates (PHA) and their blend fibers

Polyhydroxyalkanoate (PHA) is a representative biodegradable polymer with more than 150 varieties and various properties. This article reviews the research status and potential applications of PHA, and introduces the properties of four-generation commercial PHA and its research progress in blend fibers with other biodegradable materials.

Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC.

SummaryBiodegradable polyester polyhydroxyalkanoate (PHA) is a promising bioplastic material for industrial use as a replacement for petroleum-based plastics. PHA synthase PhaC forms an active dimer to polymerize acyl moieties from the substrate acyl-coenzyme A (CoA) into PHA polymers. Here we present the crystal structure of the catalytic domain of PhaC from Chromobacterium sp. USM2, bound to CoA. The structure reveals an asymmetric dimer, in which one protomer adopts an open conformation bound to CoA, whereas the other adopts a closed conformation in a CoA-free form. The open conformation is stabilized by the asymmetric dimerization and enables PhaC to accommodate CoA and also to create the product egress path. The bound CoA molecule has its β-mercaptoethanolamine moiety extended into the active site with the terminal SH group close to active center Cys291, enabling formation of the reaction intermediate by acylation of Cys291.

Microbial Polyhydroxyalkanoates and Nonnatural Polyesters.

Microorganisms produce diverse polymers for various purposes such as storing genetic information, energy, and reducing power, and serving as structural materials and scaffolds. Among these polymers, polyhydroxyalkanoates (PHAs) are microbial polyesters synthesized and accumulated intracellularly as a storage material of carbon, energy, and reducing power under unfavorable growth conditions in the presence of excess carbon source. PHAs have attracted considerable attention for their wide range of applications in industrial and medical fields. Since the first discovery of PHA accumulating bacteria about 100 years ago, remarkable advances have been made in the understanding of PHA biosynthesis and metabolic engineering of microorganisms toward developing efficient PHA producers. Recently, nonnatural polyesters have also been synthesized by metabolically engineered microorganisms, which opened a new avenue toward sustainable production of more diverse plastics. Herein, the current state of PHAs and nonnatural polyesters is reviewed, covering mechanisms of microbial polyester biosynthesis, metabolic pathways, and enzymes involved in biosynthesis of short-chain-length PHAs, medium-chain-length PHAs, and nonnatural polyesters, especially 2-hydroxyacid-containing polyesters, metabolic engineering strategies to produce novel polymers and enhance production capabilities and fermentation, and downstream processing strategies for cost-effective production of these microbial polyesters. In addition, the applications of PHAs and prospects are discussed.

Biomedical applications of microbially engineered polyhydroxyalkanoates: an insight into recent advances, bottlenecks, and solutions.

Biopolymeric polyhydroxyalkanoates (PHAs) are fabricated and accumulated by microbes under unbalanced growth conditions, primarily by diverse genera of bacteria. Over the last two decades, microbially engineered PHAs gained substantial interest worldwide owing to their promising wide-range uses in biomedical field as biopolymeric biomaterials. Because of non-hazardous disintegration products, preferred surface alterations, inherent biocompatibility, modifiable mechanical properties, cultivation support for cells, adhesion devoid of carcinogenic impacts, and controllable biodegradability, the PHAs like poly-3-hydroxybutyrate, 3-hydroxybutyrate and 3-hydroxyvalerate co-polymers, 3-hydroxybutyrate and 4-hydroxybutyrate co-polymers, etc., are available for various medical applications. These PHAs have been exploited to design in vivo implants like sutures as well as valves for direct tissue repairing as well as in regeneration devices like bone graft substitutes, nerve guides as well as cardiovascular patches, etc. Furthermore, they are also emerged as attractive candidates for developing effective/novel drug delivery systems because of their biocompatibility and biodegradability with the ability to deliver and release the drugs at a specific site in a controllable manner and, therefore widen the therapeutic window with reduced side effects. However, there still remain some bottlenecks related to PHA purity, mechanical properties, biodegradability, etc., that are need to be addressed so as to make PHAs a realistic biomaterial. In addition, innovative approaches like PHAs co-production with other value-added products, etc., must be developed currently for economical PHA production. This review provides an insight toward the recent advances, bottlenecks, and potential solutions for prospective biomedical applications of PHAs with conclusion that relatively little research/study has been performed presently toward the viability of PHAs as realistic biopolymeric biomaterials.