Your next Mojito could help save the world

Want to save the world from plastic? Have another Mojito. The Bacardi rum that turns an innocuous lime, sugar and soda drink into something delightfully not kid-friendly will soon be poured from a 100% biodegradable bottle made by microorganisms.

Polyhydroxyalkanoates, or PHA for short, are biobased and biodegradable polymers created through bacterial fermentation, and they may be our best bet for an alternative to plastics made from petrochemicals. Bacardi – owner of brands like Grey Goose vodka, Martini, Dewar’s and Bombay Sapphire – has committed to full-scale adoption of PHA packaging to reach their sustainability goals. The drinks manufacturer has vowed to be plastic free by 2030, a promise that includes replacing an annual 80 million bottles in conventional plastic with PHA-based bottles by 2023.

PHA is made when microorganisms biosynthesize polymers through fermentation of biomass – something they have been doing passionately by nature for millions of years. The biomass can also be used cooking oil, for example, that gets a second chance and is thus reused in a sensible way. The most widely commercialized microorganisms for this are Escherichia coli, but there’s a dizzying variety of wonderfully-named microorganisms being tested and commercialized as well, including Aeromonas, Azotobacter, Cupriavidus, Clostridium, Methylobacterium, Ralstonia, Pseudomonas, and Syntrophomonas. Many companies like Italy’s MAIP or the US-based Danimer Scientific have developed their own proprietary recipes for producing PHA from specific varieties. With the variety of microorganisms comes a variety of PHA biopolymers, each categorized by the length of its carbon chain (short, medium and long) and each with its own distinct thermochemical properties.

These different properties determine not just strength and heat resistance, but how long they take to biodegrade. The biodegradation of Bacardi’s new bottles is said to take 18 months, although this period can be even shorter for products with thinner material diameters. Phade, a new PHA drink straw, takes a mere 58 days to biodegrade in marine conditions (compared to more than 200 years for a conventional plastic straw). But however long it takes – and most producers of existing PHA consumer products tout biodegradation times from one to two years maximum, versus up to thousands of years for conventional plastics – the main point is that PHA is 100% biodegradable in the first place. The only by-products are water and carbon dioxide, but absolutely zero microplastics.

Despite this promising record, the industrial use of PHA is still at its very beginning. And even though organizations like GO!PHA are certainly making great efforts to bring science, industry, and the public together, challenges still remain. Because although PHA is perfect for numerous industrial applications, including food packing and even ballpoint pens, it still cannot replace all types of conventional plastics, particularly those requiring high heat resistance or longer lifespans under challenging climatic conditions.

Another challenge is the disposal of PHA products. And even though TÜV Austria, as a global certifier for industrial bioplastics, has declared PHA to be fully biodegradable in soil, water and marine conditions, you still shouldn’t chuck your rum bottle into the sea, no matter how many Mojitos you had. The more PHA and other bioplastics will be used – and this is more than desirable – the more opportunities need to be created to ensure that its great advantage, namely returning it to the cycle of nature, will be organized and open and clear to all.

Despite these challenges, PHA use is growing by leaps and bounds, so keep your spyglass handy to look out for biobased and biodegradable PHA products popping up everywhere. And hoist your drink, matey – that PHA bottle your rum came from may just save the world from plastic.

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