Plastic pollution in the world’s oceans remains one of the most urgent environmental challenges. While biobased plastics have been promoted as alternatives, many fail to degrade in marine conditions, persisting as long as conventional plastics. A research team from Shinshu University, in collaboration with JAMSTEC and Gunma University, has now demonstrated a new material that may overcome this limitation: poly(D-lactate-co-3-hydroxybutyrate), or LAHB.

Proven Biodegradation in Deep-Sea Conditions

In an experiment near Hatsushima Island, Japan, researchers submerged LAHB films at a depth of 855 metres under real-world deep-sea conditions. Over the course of 13 months, the material lost more than 80% of its mass as microbial communities colonised and actively decomposed the bioplastic. By contrast, a conventional biobased plastic, polylactide (PLA), showed no measurable signs of degradation during the same period.

The results are groundbreaking because deep-sea environments—cold, high-pressure, and nutrient-poor—are among the most challenging for microbial activity. The study confirms that LAHB can be mineralised into harmless compounds like water and carbon dioxide, even in these extreme conditions.

Microbes at Work

The researchers analysed the plastisphere, the microbial ecosystem that developed on the LAHB films. They found a network of bacteria working together to break the polymer into progressively smaller fragments, ultimately converting it into environmentally safe byproducts. PLA films, in contrast, remained intact and free from microbial colonisation.

Potential for Sustainable Design

These findings open the door for the development of truly marine-biodegradable plastics, offering designers new opportunities for reducing long-term plastic waste. For packaging design, LAHB holds particular promise as an alternative to materials that frequently end up in waterways. Product designers exploring sustainable alternatives for consumer goods may also find applications in disposable or short-lifecycle products.

For the wider design community, this innovation highlights the importance of circular and biobased materials that not only derive from renewable sources but also degrade safely at end-of-life. If scaled successfully, LAHB could contribute significantly to reducing ocean plastic pollution and advancing the transition to a circular bioeconomy.

Source: Shinshu University
Photo: Nataliya Vaitkevich