Bioplastics

Current status in the field

In 2021, 390.7 million tons of plastic were produced, with 98.5% derived from fossil fuels^[1], leading to substantial CO2 emissions of approximately 2 kg of CO2 per kg of plastic produced^[2]. Bioplastics, made from renewable sources like plants or waste, offer an eco-friendly alternative but only make up 1.5% of total production. Bioplastics are created from renewable resources such as starch, cellulose, and even proteins^[3].

Microorganisms play a key role by producing some types of bioplastics including PHA (flexible and fully biodegradable in natural environments) and PLA (rigid, biodegradable under industrial composting)^[4,5]. These plastics are currently used in many applications such as food packaging or 3D printing.

Leading companies and innovators producing PLA bioplastics include NatureWorks^[6], BASF^[7], or Total Energies Corbion^[8]; in PHA bioplastics, companies like Danimer^[9], Kaneka^[10], or TerraVerdae^[11] are pioneering sustainable solutions.

The current R&D efforts are centered on enhancing polymer production efficiency, utilizing waste as a carbon source, and improving bioplastic durability and flexibility through structural modifications^[12,13].

Figure showing 3D PLA filament from NatureWorks and straws made of PHA (https://www.goodstartpackaging.com/guide-to-pha-bioplastic-polyhydroxyalkanoates/#:~:text=PHA%2C%20or%20polyhydroxyalkanoates%2C%20is%20a,but%20without%20the%20environmental%20effects.).

Bioplastic production utilizes specific organisms: lactic acid bacteria like Lactobacillus rhamnosus and L. bulgaricus for PLA, and a range of microorganisms such as Pseudomonas, Bacillus, and Alcaligenes for PHA¹⁴.

Pseudomonas putida with PHA granules; ref 15, figure 6

These organisms provide a foundation for producing sustainable plastics, and our focus would lie on enhancing production through genetic optimization, by identifying genes that increase yield and evaluating how extremophiles can help simplify fermentation by reducing the need for sterilization or heating. Another focus on genetic tractability involves the development of tools like Tn screening and recombineering to improve bioplastic properties and enable cost-effective production.

However, some challenges in the bioplastics sector persist. Raw material costs are high, and starch-based bioplastics are currently more affordable but limited by supply chains. Production costs for bioplastics often exceed those of petroleum-based plastics, reducing their market competitiveness. Additionally, many bioplastics still lack the durability and moisture resistance of conventional plastics, impacting their application in diverse industries.