Polyethylene Terephthalate (Pet)-Degrading Bacteria in the Pelagic Deep-Sea Sediments of the Pacific Ocean

Abstract

PET is the most common type of plastic debris found in deep-sea sediments. Furthermore, it remains unknown whether it can be naturally degraded via bacteria. Herein, we surveyed the pelagic sediments obtained from the Pacific Ocean to identify bacteria capable of degrading PET. With PET as the sole carbon and energy source, 10 of 19 sites over a wide geographic range showed bacterial growth, and 1.8%–16.2% of the PET mass in these sites was removed within 2 months. Attenuated total reflectance–Fourier-transform infrared analysis confirmed PET depolymerization, which was indicated by a decrease in carbonyl and aliphatic hydrocarbon groups, and bacterial diversity analysis revealed that Alcanivorax and Pseudomonas were predominant in all 10 PET consortia. Ultraperformance liquid chromatography–mass spectrometry analysis revealed that Alcanivorax sp. A02-7 and Pseudomonas sp. A09-2 degrade PET to produce mono-(2-hydroxyethyl) terephthalate (MHET), even under mimicked deep-sea conditions of 40 MPa and 10°C. In addition, bacteria of Thalassospira, Nitratireductor, Nocardioides, Muricauda, and Owenweeksia also possess PET degradation properties. In reverse transcription quantitative PCR analysis, the gene expression level of the putative PETases and MHETases in Alcanivorax sp. A02-7 and Pseudomonas sp. A09-2 was highly increased during PET degradation. Our study highlights the role of the ubiquitous marine bacteria in plastic removal in deep-sea sediments, and provides resources and references for the acquisition of more PET hydrolytic enzymes.

Keywords: Pacific deep sea, polyethylene terephthalate, plastic biodegradation, bacterial diversity, hydrolase