Overusing non-degradable plastics causes a series of environmental issues, inferring a switch to biodegradable plastics. Polyhydroxyalkanoates (PHAs) are promising biodegradable plastics that can be produced by many microbes using various substrates from waste feedstock. However, the cost of PHAs production is higher compared to fossil-based plastics, impeding further industrial production and applications. To provide a guideline for reducing costs, the potential cheap waste feedstock for PHAs production have been summarized in this work. Besides, to increase the competitiveness of PHAs in the mainstream plastics economy, the influencing parameters of PHAs production have been discussed. The PHAs degradation has been reviewed related to the type of bacteria, their metabolic pathways/enzymes, and environmental conditions. Finally, the applications of PHAs in different fields have been presented and discussed to induce comprehension on the practical potentials of PHAs.
DOCUMENT
Melt electrowriting (MEW) enables precise scaffold fabrication for biomedical applications. With a limited number of processable materials with short and tunable degradation times, polyhydroxyalkanoates (PHAs) present an interesting option. Here, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a blend of PHBV and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHBV+P34HB) are successfully melt electrowritten into scaffolds with various architectures. PHBV+P34HB exhibits greater thermal stability, making it a superior printing material compared to PHBV in MEW. The PHBV+P34HB scaffolds subjected to enzymatic degradation show tunable degradation times, governed by enzyme dilution, incubation time, and scaffold surface area. PHBV+P34HB scaffolds seeded with human dermal fibroblasts (HDFs), demonstrate enhanced cell adherence, proliferation, and spreading. The HDFs, when exposed to the enzyme solutions and enzymatic degradation residues, show good viability and proliferation rates. Additionally, HDFs grown on enzymatically pre-incubated scaffolds do not show any difference in behavior compared those grown on control scaffolds. It is concluded that PHAs, as biobased materials with enzymatically tunable degradability rates, are an important addition to the already limited set of materials available for MEW technology.
LINK
Polyhydroxyalkanoates (PHAs) are biodegradable biopolymers (polyesters), produced by a wide range of bacterial strains. They are gaining increasing interest in different research fields, due to their sustainability and environmental-friendly properties. Additionally, PHAs are also biocompatible, which makes them interesting for tissue engineering and regenerative medicine. At the same time, they are characterized by properties ideal for 3D printing processing, such as high tensile strength, easy processability and thermoplasticity. To date, the techniques employed in PHAs printing mostly include fused deposition modeling (FDM), selective laser sintering (SLS), electrospinning (ES), and melt electrospinning (MES). In this review, we provide a comprehensive summary of the versatile and sustainably sourced bacterial PHAs, also modified by blending with natural and synthetic polymers (e.g., PLA, PGA) or combining them with inorganic fillers (e.g., nanoparticles, glass), used for 3D printing in biomedical applications. We specify focus on the printing conditions and the properties of the obtained scaffolds with a focus on the print resolution and scaffolds mechanical and biological properties. New perspectives in the emerging field of PHAs biofabrication process, characterized by sustainability and efficiency of the scaffold production, are demonstrated. The use of alternative printing techniques, i.e. melt electrowriting (MEW), and producing smart and functional materials degrading on demand under in vitro and in vivo conditions is proposed.
LINK
The valorization of biowaste, by exploiting side stream compounds as feedstock for the sustainable production of bio-based materials, is a key step towards a more circular economy. In this regard, chitin is as an abundant resource which is accessible as a waste compound of the seafood industry. From a commercial perspective, chitin is chemically converted into chitosan, which has multiple industrial applications. Although the potential of chitin has long been established, the majority of seafood waste containing chitin is still left unused. In addition, current processes which convert chitin into chitosan are sub-optimal and have a significant impact on the environment. As a result, there is a need for the development of innovative methods producing bio-based products from chitin. This project wants to contribute to these challenges by performing a feasibility study which demonstrates the microbial bioconversion of chitin to polyhydroxyalkanoates (PHAs). Specifically, the consortium will attempt to cultivate and engineer a recently discovered bacterium Chi5, so that it becomes able to directly produce PHAs from chitin present in solid shrimp shell waste. If successful, this project will provide a proof-of-concept for a versatile microbial production platform which can contribute to: i) the valorization of biowaste from the seafood industry, ii) the efficient utilization of chitin as feedstock, iii) the sustainable and (potentially low-cost) production of PHAs. The project consortium is composed of: i) Van Belzen B.V., a Dutch shrimp trading company which are highly interested in the valorization of their waste streams, hereby making their business model more profitable and sustainable. ii) AMIBM, which have recently isolated and characterized the Chi5 marine-based chitinolytic bacterium and iii) Zuyd, which will link aforementioned partners with students in creating a novel collaboration which will stimulate the development of students and the translation of academic knowledge to a feasible application technology for SME’s.
