Biodegradation of polyethylene terephthalate (PET) by diverse marine bacteria in deep-sea sediments

PET plastic waste entering the oceans is supposed to take hundreds of years to degrade and tends to accumulate in the deep sea. However, we know little about the bacteria capable of plastic degradation therein. To determine whether PET-degrading bacteria are present in deep-sea sediment, we collected the samples from the eastern central Pacific Ocean and initiated microbial incubation with PET as the carbon source. After enrichment with PET for 2 years, we gained all 15 deep-sea sediment communities at five oceanic sampling sites. Bacterial isolation for pure culture and further growth tests confirmed that diverse bacteria possess degradation ability including Alcanivorax xenomutans BC02_1_A5, Marinobacter sediminum BC31_3_A1, Marinobacter gudaonensis BC06_2_A6, Thalassospira xiamenensis BC02_2_A1 and Nocardioides marinus BC14_2_R3. Furthermore, four strains were chosen as representatives to reconfirm the PET degradation capability by SEM, weight loss and UPLC-MS. The results showed that after 30-day incubation, 1.3%-1.8% of PET was lost. De-polymerization of PET by the four strains was confirmed by the occurrence of the PET monomer of MHET and TPA as the key degradation products. Bacterial consortia possessing PET-degrading potential are prevalent and diverse and might play a key role in the removal of PET pollutants in deep oceans.