EVALUATION OF THE BIODEGRADATION CAPACITIES OF BACTERIA ISOLATED FROM MICROPLASTICS COLLECTED IN THE BARENTS SEA

During the Third National Arctic Scientific Research Expedition (TASE-III), bacterial isolates were obtained from microplastics collected using manta trawl net at 20 stations in the Barents Sea. The biodegradation capacities of these isolates were investigated for commercial polyethylene (PE) and fibril-type microplastics (MPs). From the 80 strains isolated, 10 strains with the highest biodegradation potential were selected in the first phase and subjected to detailed analysis in the second phase. In the second phase, the selected isolates were incubated for 40 days at 25°C in 500 mL flasks containing 300 mL Minimal Salt Medium, with a 1% bacterial inoculation rate. Each flask was supplemented with 0.5 g of commercial PE and fibril MPs collected from the field. Growth curves were recorded by measuring absorbance at OD600 nm using a spectrophotometer, with samples taken every 5 days. Gravimetric weight loss was calculated by filtering the microplastics through a 0.45-μm membrane filter, washing them with 70% ethanol, drying at 50°C for one day, and weighing on a precision balance, applying the relevant formula. The highest biodegradation rate on commercial PE was recorded at 43.46% by Bacillus pumilus (D2SRB20.3). On MPs, the highest biodegradation rate of 20.51% was observed with the Staphylococcus hominis (D3SRB30) isolate. Additionally, FTIR and SEM analyses were performed on the samples with high biodegradation rates. FTIR results revealed chemical bond changes and degradation of aliphatic chains on the polymer surface, while SEM images confirmed morphological changes such as cracks and roughness on the polymer surface. This study was supported by the TUBITAK KUTUP-1001 program (Project No: 122G270). We would like to thank TUBITAK for their support. FTIR and SEM analyses were performed by Yıldız Technical University Science and Technology Application and Research Center (BİTUAM).