Daejeon, South Korea – With so much polyurethane waste ending up in landfill, new ways of breaking it down effectively and safely are very much needed. One way would be by biodegradation, and while PU-degrading enzymes have started to be identified as the bacteria that produce them evolve to accommodate changing environmental conditions, much more research is needed if biodegradation is to become a viable waste management option.
Now, a team at the Korea Research Institute of Bioscience and Biotechnology’s Microbiome Convergence Research Centre has looked at the potential of a lipase enzyme isolated from the Asian mantis Hierodula patellifera. The insects were collected in the Bomoon mountain area near Daejeon.
A Serratia sp. HY-72 bacterial strain that produces a PU-degrading lipase was isolated from the insects’ intestines. After incubating a bacterial filtrate with the colloidal polyester-PU dispersion Impranil for 72h, a bacterial filtrate gave 85% degradation. A recombinant form of the hydrolytic enzyme degraded the PU by 78%.
They also found that the strain was able to degrade a commercial polyester PU foam, giving 24% weight loss after two weeks of incubation at 30°C. Similarly, it gave an 11% weight reduction for a commercial polyether PU foam. Scanning electron microscopy showed that in both cases the foam structure had been disrupted, with holes, cracks and roughness developing. The foams were supplied by Seoul-based KPX Chemical.
The team suggested that this insect-associated microbe could indeed prove a promising resource for the biodegradation of waste PU. They added that this is the first time PU degrading ability has been identified in a species of Serratia bacteria.
The work has been published in the journal Frontiers in Microbiology.
