Introducing the potential of a newly isolated yeast strain, SlgEBL۵ in untreated polyethylene terephthalate microplastic biodegradation

BACKGROUND AND OBJECTIVESPolyethylene terephthalate (PET), a heteroatomic, semi-aromatic polyester, is among the most manufactured and used plastic polymers, only ۴۰% of its post-consuming products are recycled and the remaining are released to nature. Facing these plastic residues to the abiotic factors of the environment will fragment them into micro-sized secondary particles, called microplastics that could enter the food web and reach the human body through biomagnification. Among the methods for microplastic remediation, biodegradation is known as an eco-friendly and cost-effective method to remove environmental pollutants and draw scientific society's attention to removing microplastics in recent years. This study aims to introduce a new PET-degrading yeast strain and assess its biodegradation efficiency.MATERIALS AND METHODSA PET-degrading yeast strain was isolated from activated sludge in the mineral-based carbon-free medium containing PET microplastics as the sole carbon source and selected based on the qualified lipase and esterase assessments. The selected isolate was identified through ITS sequencing and assessed for PET microplastic biodegradation ability through Scanning Electron Microscopy (SEM), Gas Chromatography-Mass Spectroscopy (GC-MS), Fourier Transform Infrared spectroscopy (FTIR), Detection-Light Scattering (DLS), zeta potential analysis, and microplastic's weight loss measurement.RESULTS AND DISCUSSIONThe results showed that the isolate is a new strain of Vanrija sp., that could decrease ۱۰% of the PET microplastic weight after ۳۰ days. SEM micrographs revealed its colonization and crack creation on PET microplastic surface, making them ۴۰.۶ times smaller, as the DLS results revealed, and shifting their zeta potential from -۱۹.۳ to +۳۱.۰. Comparing the FTIR spectrum of treated and untreated microplastics also proved the decrement in PET crystallinity and intensity of the amorphous fragments of this polymer, releasing benzene and alkane derivates as by-products.CONCLUSIONCombining these findings, it can be concluded that Vanrija sp. SlgEBL۵ has an acceptable degrading function as a biological treating agent for PET microplastics.

کلیدواژه ها:

Biodegradation ، Microplastic ، Polyethylene Terephthalate ، Vanrija sp.