Plastic is biodegradable, new study shows

Amid the bleak scenario of Metro Manila’s worsening garbage problem comes this bit of good news: a new study finds that plastic, which to date has only been disposed of through recycling, is also biodegradable.

The results of the study by Jose Mallari, which discovered that microorganisms in Philippine soil can degrade or turn polybeta-hydroxybutyrate (PHB) or plastic into compost, was announced by the Philippine Council for Health Research and Development of the Department of Science and Technology (PCHRD-DOST) in a recent public health forum held at the University of the Philippines-Manila.

The finding was actually an offshoot of Mallari’s thesis on "Antibiotic Production by Polybeta-hydroxybutyrate (PHB)-degrading Microorganisms," which primarily aimed to show the potential of PHB degraders for antibiotic production. In the process of conducting the study, the organisms isolated were found to be useful in composting plastic.

Mallari’s thesis builds on previous studies on the biodegradability of natural and synthetic polymers. Among the biodegradable plastics that attracted the most attention in industry and biomedicine are the aliphatic polyesters such as polybeta-hydroxybutyrate (PHB).

These polymers are decomposed through the action of organisms, particularly bacteria and fungi. Polybeta-hydroxybutyrate, a linear polymer of B-hydroxylate, is produced within the cells as energy reserve by a range of prokaryotic cells.

These bacteria create hydroxybutyrate from glucose, which can be sourced from corn, molasses, wheat, starch or alcohol. Since glucose source materials are readily available in our country, PHB offers an inexpensive alternative to petrochemically derived plastic.

The results of Mallari’s study also provide a new perspective to composting. Prior to the study, composting was only thought to be applicable to biodegradable wastes. That plastic is also biodegradable should be welcome news to environmentalists.

The disposal of used plastic has long been a cause of concern. In the Philippines, approximately 120,000 tons of plastic are generated each year, 50 percent of which end up as litter. Like other solid wastes, conventional plastic is resistant to microbial degradation. Plastic cannot also be disposed of through burning since plastic fumes cause a wide range of ailments, including skin diseases, asthma and some forms of cancer. Even recycling, widely endorsed to reduce solid wastes, does not effectively reduce the volume of used plastic.

Like other bright ideas, however, Mallari’s study needs the support, not only of the public, but more so of industry players and policy-makers.

Developed countries have legislations in place that mandate the use of degradable plastic. Philippine lawmakers have also been recommending the phaseout of non-biodegradable materials. But unless industry players provide their full support, this breakthrough finding in waste management would end up like other innovations in the past – shelved and forgotten.