Degradation Activity Screening for Compostable Bioplastics of Fungal species isolated from Freshwater Environment

Degradation Activity Screening for Compostable Bioplastics of Fungal species isolated from Freshwater Environment

Sangkyu Park*, Hye Yeon Mun, Wonsu Cheon, Yoosun Oh

Fungi Research Division, Biological Resource Research Department, Freshwater Bioresources Research Office, Nakdonggang National Institute of Biological Resources, Sangju, Gyeongsangbuk-do, 37242, South Korea

*Email: skpark79@nnibr.re.kr

Biodegradable plastics have been developed to replace conventional petroleum-based plastics to reduce plastic waste. Biodegradable plastics are divided into two types: “biodegradable” plastics and “compostable” plastics. Compostable plastics account for the largest market size in the bioplastic market due to their excellent physical properties. However, they require harder conditions(industrial composting condition, 58℃) to decompose. Therefore, compostable plastics have significantly low decomposition rate under general landfill condition, which also affects the reduction of waste. Therefore, it is important to make the decomposition conditions of these biodegradable plastics easier.

In this study, we tried to find fungal strains which able to decompose compostable plastics under biodegradable condition, 25℃. We selected poly lactic acid(PLA), the most widely used compostable plastic, as target material. First, we studied the decomposition mechanism of PLA and related enzymes with previous study. Then we quantitatively analyzed the activity of enzymes involved in the degradation of PLA among 130 fungal strains which isolated from freshwater related environment. selected 4 fungal strains which have high enzyme activity. We selected fungal strains with high enzyme activity and treated commercially available PLA product with liquid cultured media. Finally, we analyzed the degradation rates over time under biodegradable condition. As the result, 4 fungal strains including Apiotrichum porosum NNIBRFG1603 strain showed high PLA degradation rate under biodegradable conditions. Under 25℃ condition, 90% of PLA product was degraded within 6 months which means that PLA can be decomposed under general landfill condition.