Fukushima Univ. team finds world's 1st polypropylene-dissolving microbe

A team of researchers at Fukushima University has found a microorganism that efficiently dissolves polypropylene, a type of plastic used for bottle caps and other products, the first discovery of its kind in the world. Daisuke Sugimori, a professor at the university's Faculty of Symbiotic Systems Science who heads the team, announced the discovery on May 11. It is difficult to recycle polypropylene for reuse and the material is usually disposed of by incineration. However, if the dissolution process involving the microbe is commercialized, it is expected to lead to significant restraints on carbon dioxide (CO2) emissions and the recycling of more resources. Polypropylene is very strong and used in items that prevent drinks from leaking, including plastic bottle caps. It is generally incinerated because of the difficulty in recycling, leading to CO2 emissions, considered the leading cause of global warming. How to dispose of polypropylene has become a challenging issue. While Sugimori and his team continued dissolution experiments using microorganisms, Shiori Hotta, a 19-year-old team member and a second-year student at the Faculty of Food and Agricultural Sciences, found last year a microbe in a sample of soil taken from the university's campus that efficiently dissolves polypropylene. In an experiment in which a flake taken from a plastic bottle cap was soaked in a solution containing the microbe, up to 64% of the flake in terms of weight was dissolved into fine filamentous pieces. Sugimori said the dissolution appears to be the work of a type of enzyme in the microbe, but the actual mechanism has yet to be known. His team will push ahead with research primarily on what enzyme characteristics are at play in the microbe, giving it the ability to dissolve polypropylene. Soon after the mechanism is made clear, the research team will acquire genetic information from the microbe and culture a microbe that would have an enzyme capable of completely dissolving polypropylene in order for recycling to be possible in the future. Of the total amount of waste plastics, polypropylene is the second largest behind polyethylene, known for being used for plastic shopping bags. Incinerating plastic bottle caps generates a huge amount of CO2, as well as harmful materials such as dioxin, according to Sugimori. Bacteria that dissolve polyethylene terephthalate (PET), a material used widely for plastic bottles, have already been discovered and put into practical use. Sugimori and his team have set their sights on setting up a business venture to be originated from Fukushima University in the future as they hope to take advantage of technology that would enable total dissolution and recycling of polypropylene. "We would like to move our research forward, then firmly establish a new business in our prefecture and continue making contributions to preserve the global environment," Sugimori said. (Translated by Kyodo News)