Production of Polyhydroxyalkanoate (PHA) Biopolymers from Waste Materials

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Circular and Green Polymer Science".

Deadline for manuscript submissions: closed (28 February 2022) | Viewed by 16579

Special Issue Editor

Department of Microbiology and Mycology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10719 Olsztyn, Poland
Interests: biopolymers; antimicrobial agents; microbial fermentation; metabolic engineering; synthetic biology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Problems related to plastic waste and its negative effects on the environment have resulted in the emergence of a wide range of biodegradable polymer materials. Among the biomass-derived polymers, there is a growing interest in polyhydroxyalkanoates (PHAs). They are polyesters synthesized intracellularly by microorganisms and stored as reserve materials, allowing for survival under unbalanced nutritional conditions. Despite the highly satisfactory properties of PHAs, their production costs are still high compared with their synthetic alternatives. Therefore, there is a growing need for the development of novel microbial processes using inexpensive carbon sources. Such substrates could be waste materials that create problems with waste management and water pollution.

This Special Issue intends to cover the latest developments in the microbial synthesis of polyhydroxyalkanoates using waste streams. Topics will include the utilization of wastes for PHAs production by pure, recombinant, and mixed microbial cultures; new approaches to produce PHA in a sustainable fashion; novel microbes as PHAs producers; and polymer characterization.

Keywords

  • high cell-density culture
  • polyhydroxyalkanoate
  • pure/mixed cultures
  • metabolic engineering
  • waste materials

Published Papers (4 papers)

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Research

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15 pages, 1178 KiB  
Article
Screening for Methane Utilizing Mixed Communities with High Polyhydroxybutyrate (PHB) Production Capacity Using Different Design Approaches
by Rana Salem, Moomen Soliman, Ahmed Fergala, Gerald F. Audette and Ahmed ElDyasti
Polymers 2021, 13(10), 1579; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13101579 - 14 May 2021
Cited by 12 | Viewed by 2925
Abstract
With the adverse environmental ramifications of the use of petroleum-based plastic outweighing the challenges facing the industrialization of bioplastics, polyhydroxyalkanoate (PHA) biopolymer has gained broad interest in recent years. Thus, an efficient approach for maximizing polyhydroxybutyrate (PHB) polymer production in methanotrophic bacteria has [...] Read more.
With the adverse environmental ramifications of the use of petroleum-based plastic outweighing the challenges facing the industrialization of bioplastics, polyhydroxyalkanoate (PHA) biopolymer has gained broad interest in recent years. Thus, an efficient approach for maximizing polyhydroxybutyrate (PHB) polymer production in methanotrophic bacteria has been developed using the methane gas produced in the anaerobic digestion process in wastewater treatment plants (WWTPS) as a carbon substrate and an electron donor. A comparison study was conducted between two experimental setups using two different recycling strategies, namely new and conventional setups. The former setup aims to recycle PHB producers into the system after the PHB accumulation phase, while the latter recycles the biomass back into the system after the exponential phase of growth or the growth phase. The goal of this study was to compare both setups in terms of PHB production and other operational parameters such as growth rate, methane uptake rate, and biomass yield using two different nitrogen sources, namely nitrate and ammonia. The newly proposed setup is aimed at stimulating PHB accumulating type II methanotroph growth whilst enabling other PHB accumulators to grow simultaneously. The success of the proposed method was confirmed as it achieved highest recorded PHB accumulation percentages for a mixed culture community in both ammonia- and nitrate-enriched media of 59.4% and 54.3%, respectively, compared to 37.8% and 9.1% for the conventional setup. Finally, the sequencing of microbial samples showed a significant increase in the abundance of type II methanotrophs along with other PHB producers, confirming the success of the newly proposed technique in screening for PHB producers and achieving higher PHB accumulation. Full article
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19 pages, 2518 KiB  
Article
Blends of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) with Fruit Pulp Biowaste Derived Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate-co-3-Hydroxyhexanoate) for Organic Recycling Food Packaging
by Beatriz Meléndez-Rodríguez, Sergio Torres-Giner, Maria A. M. Reis, Fernando Silva, Mariana Matos, Luis Cabedo and José María Lagarón
Polymers 2021, 13(7), 1155; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13071155 - 04 Apr 2021
Cited by 20 | Viewed by 3979
Abstract
In the present study, a new poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) [P(3HB-co-3HV-co-3HHx)] terpolyester with approximately 68 mol% of 3-hydroxybutyrate (3HB), 17 mol% of 3-hydroxyvalerate (3HV), and 15 mol% of 3-hydroxyhexanoate (3HHx) was obtained via the mixed microbial culture (MMC) [...] Read more.
In the present study, a new poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) [P(3HB-co-3HV-co-3HHx)] terpolyester with approximately 68 mol% of 3-hydroxybutyrate (3HB), 17 mol% of 3-hydroxyvalerate (3HV), and 15 mol% of 3-hydroxyhexanoate (3HHx) was obtained via the mixed microbial culture (MMC) technology using fruit pulps as feedstock, a processing by-product of the juice industry. After extraction and purification performed in a single step, the P(3HB-co-3HV-co-3HHx) powder was melt-mixed, for the first time, in contents of 10, 25, and 50 wt% with commercial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Thereafter, the resultant doughs were thermo-compressed to obtain highly miscible films with good optical properties, which can be of interest in rigid and semirigid organic recyclable food packaging applications. The results showed that the developed blends exhibited a progressively lower melting enthalpy with increasing the incorporation of P(3HB-co-3HV-co-3HHx), but retained the PHB crystalline morphology, albeit with an inferred lower crystalline density. Moreover, all the melt-mixed blends were thermally stable up to nearly 240 °C. As the content of terpolymer increased in the blends, the mechanical response of their films showed a brittle-to-ductile transition. On the other hand, the permeabilities to water vapor, oxygen, and, more notably, limonene were seen to increase. On the overall, this study demonstrates the value of using industrial biowaste derived P(3HB-co-3HV-co-3HHx) terpolyesters as potentially cost-effective and sustainable plasticizing additives to balance the physical properties of organic recyclable polyhydroxyalkanoate (PHA)-based food packaging materials. Full article
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Review

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21 pages, 1161 KiB  
Review
What Is New in the Field of Industrial Wastes Conversion into Polyhydroxyalkanoates by Bacteria?
by Paulina Marciniak and Justyna Możejko-Ciesielska
Polymers 2021, 13(11), 1731; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13111731 - 26 May 2021
Cited by 10 | Viewed by 3107
Abstract
The rising global consumption and industrialization has resulted in increased food processing demand. Food industry generates a tremendous amount of waste which causes serious environmental issues. These problems have forced us to create strategies that will help to reduce the volume of waste [...] Read more.
The rising global consumption and industrialization has resulted in increased food processing demand. Food industry generates a tremendous amount of waste which causes serious environmental issues. These problems have forced us to create strategies that will help to reduce the volume of waste and the contamination to the environment. Waste from food industries has great potential as substrates for value-added bioproducts. Among them, polyhydroxyalkanaotes (PHAs) have received considerable attention in recent years due to their comparable characteristics to common plastics. These biodegradable polyesters are produced by microorganisms during fermentation processes utilizing various carbon sources. Scale-up of PHA production is limited due to the cost of the carbon source metabolized by the microorganisms. Therefore, there is a growing need for the development of novel microbial processes using inexpensive carbon sources. Such substrates could be waste generated by the food industry and food service. The use of industrial waste streams for PHAs biosynthesis could transform PHA production into cheaper and more environmentally friendly bioprocess. This review collates in detail recent developments in the biosynthesis of various types of PHAs produced using waste derived from agrofood industries. Challenges associated with this production bioprocess were described, and new ways to overcome them were proposed. Full article
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19 pages, 1529 KiB  
Review
Volatile Fatty Acids as Carbon Sources for Polyhydroxyalkanoates Production
by Karolina Szacherska, Piotr Oleskowicz-Popiel, Slawomir Ciesielski and Justyna Mozejko-Ciesielska
Polymers 2021, 13(3), 321; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13030321 - 20 Jan 2021
Cited by 40 | Viewed by 4841
Abstract
Waste of industrial origin produced from synthetic materials are a serious threat to the natural environment. The ending resources of fossil raw materials and increasingly restrictive legal standards for the management of plastic waste have led to research on the use of biopolymers, [...] Read more.
Waste of industrial origin produced from synthetic materials are a serious threat to the natural environment. The ending resources of fossil raw materials and increasingly restrictive legal standards for the management of plastic waste have led to research on the use of biopolymers, which, due to their properties, may be an ecological alternative to currently used petrochemical polymers. Polyhydroxyalkanoates (PHAs) have gained much attention in recent years as the next generation of environmentally friendly materials. Currently, a lot of research is being done to reduce the costs of the biological process of PHA synthesis, which is the main factor limiting the production of PHAs on the industrial scale. The volatile fatty acids (VFAs) produced by anaerobic digestion from organic industrial and food waste, and various types of wastewater could be suitable carbon sources for PHA production. Thus, reusing the organic waste, while reducing the future fossil fuel, originated from plastic waste. PHA production from VFAs seem to be a good approach since VFAs composition determines the constituents of PHAs polymer and is of great influence on its properties. In order to reduce the overall costs of PHA production to a more reasonable level, it will be necessary to design a bioprocess that maximizes VFAs production, which will be beneficial for the PHA synthesis. Additionally, a very important factor that affects the profitable production of PHAs from VFAs is the selection of a microbial producer that will effectively synthesize the desired bioproduct. PHA production from VFAs has gained significant interest since VFAs composition determines the constituents of PHA polymer. Thus far, the conversion of VFAs into PHAs using pure bacterial cultures has received little attention, and the majority of studies have used mixed microbial communities for this purpose. This review discusses the current state of knowledge on PHAs synthesized by microorganisms cultured on VFAs. Full article
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