Surface modification ability of Paracoccus sp. indicating its potential for polyethylene terephthalate degradation

Plastic products are now globally used for their superior performance, they have brought tremendous conve-nience to modern life. While the ensuing plastic contamination during the whole life cycle poses significant pressure to the ecosystem. Therefore, scientific methods for tackling this issue are urgently needed. Here in this paper, we isolated and purified a bacterial strain (LSH-W) from Loushanhe Estuary by using concentration gradient as pressure for selection and this strain can grow in the mineral medium with bis (2-hydroxyethyl) terephthalate (BHET) as the sole carbon and energy source. The strain was later identified as Paracoccus sp. by 16S rRNA gene sequencing. Based on the optimization experiment, 30 C and pH = 8 were proved to be the optimal culture condition. Afterwards, the potential of strain LSH-W for PET degradation was verified through an experiment with PET film as the sole substrate in mineral medium. We found that after 40 days of biotreatment, surface properties of PET film were modified, the decrease of water contact angle (WCA) indicated an improvement of surface hydrophobicity, the analysis of functional groups on the surface by using FTIR and XPS showed that the ester bonds were hydrolyzed. Together with erosions, breakages and gullies demonstrated in SEM micrograph, surface modification ability and potential for PET degradation of LSH-W can be demonstrated. The surface modification can further contribute to the attachment and colonization of bacteria on PET film, which is widely recognized to play a key role in the proceeding of further biodegradation, and this study would be a valuable attempt with its application in treatment of plastic pollution.