Plastic is the staple material of modern life, and a sustainable future will need bioplastics. What is Biotech doing to make this happen?
“What do you include in bioplastics? Because bioplastics is a very large word“, laughed Emmanuel Maille, Director of Strategy and Development at Carbios. It’s a large word indeed. Bioplastics can be ‘bio’ in different ways: they can be biodegradable, they can be made of materials or chemicals of biological origin (like corn or lactic acid), or they can be produced directly through fermentation. We asked Maille, as well as Evonic and BASF, to help us break it down.
Despite all the exciting research and breakthroughs in the field, the market for bioplastics remains small. According to World Watch, the worldwide production of plastic is now roughly 300 million tons. Meanwhile, the production capacity for bio-based plastics was estimated to be around 1.7 million tons in 2014 – a meager 0.6% of the total market – and the production of plastics that are both bio-based and biodegradable was 700k tons.
Both are expected to grow fast, however. An estimated 7.8 million tons of bio-based plastic could be produced by 2019, with the share of biodegradable polymers reaching 1.2 million tons.
A key driver in the field is governmental policy, specifically regulations and incentives. The ‘stick’ moving the field forward in Europe appears to be strict French regulation, including a ban on oxo-biodegradable plastics, whose fragments persist in nature, and enforcing increases in bio-based material content in plastic blends.
As the ‘carrot’, the governments and the European Union supported research and initiatives in bioplastics. For example, EU’s main funding scheme, Horizon 2020, supported bioplastic programs like Synpol. Bioplastic-focused companies also usually find funding in government institutions.
Come on, Biology, let’s go party!
Plastics are a tough waste problem, as many types can persist in the environment for centuries. Some plastics, however, can be degraded by microorganisms. One example is BASF’s biodegradable polymers, which include Ecoflex, a petrochemical-based polyester.
However, switching entirely to biodegradable plastics is a big challenge. Plastic is used in many different applications, which have different requirements regarding physical and chemical properties, met by different types of polymers. A biodegradable alternative may not be easily available.
Biotech is hard at work on this degradation problem. Possible solutions range from developing plastics that can degrade in the ocean, finding microbes with exotic enzymes capable of degrading a type of plastic (through bio-mining, for example) as part of waste treatment, evolution machines, or developing the relevant enzymes through protein engineering (one of toughest parts of SynBio).
For example, Carbios developed an ‘infinite recycling‘ process, where enzymes break down polymers into monomers. These monomers can then be reused to make plastic again. Unlike the traditional method of recycling, where plastics are shredded, ‘melted’ and processed again, this enzymatic recycling still allows for high-quality plastic. This strategy was successful with PET, a type of plastic that is everywhere (plastic bottles) and is hard to recycle.
In the future, we expect to have enzymes for each type of polymer. So we could have an iterative process to recycle any type of plastic, without the need for sorting, and we can recover the monomers that interest us.” Emmanuel Maille (Carbios)
These enzymes can also be incorporated in certain polymers to create custom biodegradability. Carbios develops this technology for single-use plastics that have a defined lifetime, such as packaging or agriculture films.
“Imagination…your creation”: What about bio(based) plastics?
Bioplastics is also a common term for plastics that were made out of biomass – be it corn starch, vegetable oils or fats, or chemicals produced by microbes. The main goal is to be able this much-needed material for everyday life, without relying on petroleum, since it is a finite resource. To be more accurate, they should be called bio-based polymers (according to IUPAC, the royalty of chemical-related terminology).
The star of bio-based polymers is probably PLA, which has the potential to replace PET in many applications. PLA the result of polymerizing lactic acid, a chemical obtainable by fermentation. Netherlands-based Corbion Purac is producing PLA and other bio-based alternatives; other European players include Synbra (Netherlands) and Futerro (France).
Another company in the field is Avantium (also Dutch), a Shell spin-off developing polyethylene furanoate (PEF) from corn-derived sugars to replace PET in bottles. Unlike PLA, PEF can be told apart from PET during sorting for recycling. It was successful enough to strike a deal to make Coca-Cola bottles.
However, for bio-based plastics to compete with using petrochemical resources, there’s the challenge of price. Of all the tons of plastic produced annually, a large part are for industrial, disposable or mass-produced applications. This means the plastics market navigates the cutthroat economics of commodities, where price is king.
One solution is to take the knowledge of bioplastics to value-added applications, such as medicine. For example, Evonik is currently investing in medical implants made out of biocompatible and biostable platstic to replace metal. There are also other niche applications bio-based plastics can have an edge, such as packaging for cosmetics. L’Oréal, for example, boasts its 100% bio-sourced bottles.
However, some bio-based plastics may not be a sustainable solution. Like first-generation biofuels, competition with food resources is a problem. Access to raw materials can also be tricky for the bioplastic industry. For instance, there are sugar access quotas that can change over time and make the production suddenly unfeasible. In fact, these quotas have been tightening up, even in places like China.
Access to sugars is a major challenge for the industry of bio-based plastics”. Emmanuel Maille
Biotech also has solutions for this, such as the biorefinery concept. The idea is to develop microbial strains that can ‘eat’ green waste (like wood residues), which are cheap and widely available. From the waste, the biorefinery would produce key chemicals, that are later used for a wide range of applications – including plastics.
Corbion and BASF formed a joint venture, Succinity, to realize this idea. Another example is Italy-based Novamont with its Matrica project to produce chemicals used in the plastic industry, such as PVC plasticizers. Global Bioenergies is also pursuing bio-based isobutene to make plastics.
“I can act like a star”: Cells as Plastic Factories
So, we have covered how cells can be used to create the building blocks of plastic and bypass the need for oil. But synbio can go even further, and create a cell factory of plastic.
Some microbes naturally produce polymers that we can use as plastics. PHAs, for example, are produced by a number of microorganisms and can be used in food packaging and other disposable items like diapers.
Through strain and fermentation optimization, some companies like US-based Metabolix have managed to produce PHAs from bacteria at an industrial scale. Last year, Bio-on and Cristal Union announced plans to build a PHA plant in France. However, Metabolix recently announced it was cutting back its biopolymers operations, mostly due to price and the limited applications of the polymer.
There are other highly-versatile polymers but there are no known natural metabolic pathways. Metabolic and protein engineering can help. Carbios recently announced that it had managed to create a metabolic pathway for production of PLA in collaboration with its academic partner, INRA Toulouse. For Carbios, creating a metabolic pathway for PLA made it a more cost-effective material so the company could compete directly with petrochemical plastics.
When I asked if there were more types of polymers that could be unlocked with cell factories, Carbios did say it had a similar solution for PHA. However, it will not be its main focus as the company develops the other three sides of its bioplastics business.
On the other hand, bioplastics still have a hard time competing head-on with petrochemical plastics. The future of bioplastics is mainly driven by regulations and the principle of environmental concern rather than a ‘real’ market need. Although it’s far from ideal to be largely dependent on political goodwill, the requirements for biodegradable and bio-based plastics are getting more and more stringent, which will drive not only the growth of bioplastics but the technology behind it.
There are a lot of different ways for bioplastics to grow, and a lot of work has to be done. But in the short-term, watch out for soon-to-be-mandated 50% bio-based plastic bags in French supermarkets!
Feature Image Credit: Pixabay
Figure 1 Credit: Lasure et al. (2004) Bioconversion and Biorefineries of the Future. Report from the Pacific Northwest National Laboratory and National Renewable Energy Lab.
Figure 2 (left) Credit: Tian et al. (2005) Kinetic Studies of Polyhydroxybutyrate Granule Formation in Wautersia eutropha H16 by Transmission Electron Microscopy. Journal of Bacteriology (doi: 10.1128/JB.187.11.3814-3824.2005)
Figure 2 (right) Credit: Korotkova and Lidstrom (2001) Connection between Poly-β-Hydroxybutyrate Biosynthesis and Growth on C1 and C2 Compounds in the Methylotroph Methylobacterium extorquens AM1. Journal of Bacteriology (doi: 10.1128/JB.183.3.1038-1046.2001)
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