From Industrial and Plastic Waste to Bioplastics: Harnessing Haloferax mediterranei for Sustainable PHBV Production (FREE)

In the European Union (EU) between 118 and 138 million tonnes of biowaste are generated annually, and about 40 % is currently being landfilled or incinerated. Landfilling is considered a principal source of methane (11 %) and accounts for 15-22 % of greenhouse gas emissions related to food losses and waste in the EU. Moreover, over 70 million tons of polyethylene terephthalate (PET) are produced globally, primarily for packaging. While conventional waste management strategies focus on disposal or limited recycling, emerging biotechnological approaches aim to convert these waste streams into valuable and sustainable materials. A promising example is the production of polyhydroxyalkanoates (PHAs), such as polyhydroxybutyrate-valerate (PHBV), using specialised microorganisms.

The upPE-T Project introduces an innovative framework for bioplastic production by combining industrial and plastic waste streams in a circular economy model. Industrial confectionery residues and PET-derived hydrolysates—primarily containing terephthalic acid (TPA)—serve as feedstocks in a two-step microbial process developed by CETEC Biotechnology. TPA is first metabolised by Comamonas testosteroni, a bacterium capable of degrading phthalates, to generate biomass. This biomass, rich in nutrients, is then utilised alongside the confectionery waste by the halophilic archaeon Haloferax mediterranei. Through this process, H. mediterranei produces Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biodegradable bioplastic with diverse industrial applications.

This integrated strategy not only demonstrates an effective approach for recycling PET and organic waste but also emphasises the potential of microbial and enzymatic technologies to address environmental challenges. By turning waste into sustainable resources, the project paves the way for scalable bioplastic production while reducing reliance on traditional, fossil fuel-based materials.

A two-step process: from PET hydrolysates to PHBV

This innovative system combines the strengths of two microbial species to repurpose plastic and organic waste into PHBV.

Enzymatic hydrolysis of PET results in terephthalic acid (TPA) and ethylene glycol as primary by-products. TPA monomers are classified as reproductive toxicants due to their ability to contaminate the environment and potentially disrupt biological systems. Their stable aromatic ring structure poses a significant challenge for upcycling, as it resists both biodegradation and chemical transformation. However, Comamonas testosteroni has shown promise in overcoming this barrier. This bacterium produces specialised enzymes capable of breaking the aromatic ring of TPA, metabolising it into simpler compounds. Through this process, C. testosteroni generates biomass enriched with essential nutrients, which can be further utilised in other biotechnological processes.

In the framework of the upPE-T project, the biomass produced by C. testosteroni is combined with the confectionary waste to serve as a carbon and nitrogen source for Haloferax mediterranei, which is a halophilic archaeon recognised for its ability to synthesize PHAs, particularly PHBV, using a wide variety of nutrient sources.

PHBV is highly valued for its versatility, as it combines excellent mechanical properties similar to conventional plastics with the advantage of being biodegradable. PHBV has a wide range of applications, including packaging, agricultural films, and biomedical uses such as wound dressings and drug delivery systems.

Optimising Haloferax mediterranei for scalable PHBV production

PHBV production using microorganisms like Haloferax mediterranei offers a sustainable alternative to petroleum-derived plastics, reducing environmental impact and aligning with global efforts to promote a circular bioeconomy. Haloferax mediterranei is particularly suited for industrial-scale PHBV production due to its extreme halophilic nature, which enables it to thrive in highly saline environments. This unique characteristic allows the microorganism to utilise alternative water sources such as seawater, brines, or industrial saline wastewaters, further enhancing its environmental and economic benefits. Additionally, its halophilic metabolism lowers the risk of contamination, reducing the need for strict sterile conditions, and minimises energy consumption and operational costs, as it eliminates the need for expensive stainless-steel equipment typically required in conventional biotechnological processes.

As part of the upPE-T project, CETEC Biotechnology has developed a robust process for producing PHBV with varying monomer compositions at both laboratory and pilot scales, optimising the nutrient composition of the production medium and fine-tuning the operational parameters to achieve high-quality PHBV suitable for packaging applications. This process has also been scaled up to pilot plant level, where it was successfully tested in 300 L plastic bioreactors designed by CETBIO, demonstrating the feasibility of large-scale PHBV production using this innovative biotechnological approach.

The project’s latest findings will be presented in a final webinar this April, where professionals from industry and academia will discuss enzymatic PET upcycling, PHBV production, and its potential role in future plastic waste management strategies.

Learn more about upPE-T: https://www.uppet.eu/

CETEC Biotechnology: https://www.cetecbiotechnology.es/

upPE-T project has received funding from the European Union’s H2020 Programme for research, technological development and demonstration under Grant Agreement 953214.

CETEC Biotechnology S.L.

CETEC Biotechnology is a spin-off from the Technological Center of Footwear and Plastic of the Region of Murcia (CETEC). It is specialised in the research and development of biotechnological processes for the production of bio-based and biodegradable polymers, mainly focusing on polyhydroxyalkanoates (PHAs). The company aims to transform bioplastics into a sustainable and competitive alternative to conventional plastics through circular economy innovations: using industrial waste as raw material and employing halophilic microorganisms in the process.

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