PET biodegradation

Background and Aim: Introduction: Polyethylene terephthalate (PET) is a high-molecular-weight thermoplastic polymer consisting of diethyl terephthalate (DET) monomers of terephthalic acid (TPA) and ethylene glycol. This polymer is one of the most widely used plastics in the world with applications in industries such as packaging, furniture, body implants. Due to the high consumption of these polymers and features of this polymer such as non-degradability, resistance to moisture and high durability, PET accumulates in nature and is eventually consumed as microplastics by fish and other aquatic organisms. PET therefore, enters the food chain with negative effects on human and animal health as well as dire environmental consequences. Only few bacteria and fungi have been identified that are capable of PET degradation. Most of the bacteria identified with the ability to degrade PET belong to gram-positive of Actinobacteria. The enzymes involved in PET degradation are often α/β hydrolases like cutinase. Methods: Methods: In this study, the ability of PET degradation by Actinomycetes capable of degrading polyethylene (PE) was assessed.. Samples were cultured in LB broth medium, incubated in ۳۷˚c and ۱۵۷ rpm for ۴۸ hours and centrifuged at ۷۰۰۰rpm for ۱۰ min. The pellet was washed several times with Bushnell Hass (BH) broth medium and inoculated in ۳۰ cc this medium. PET films were cut in ۲x۳ cm sizes and shaken in ۷۰% ethanol for ۱ hour. These films were then placed in inoculated BH broth medium and incubated in ۳۷˚c and ۱۵۷ rpm for ۷۰ days. The growth of bacterial cells on PET films and degradation of PET were evaluated with SEM imaging. Result and Discussion: According to the SEM images, bacterial isolates K۲, T۲, K۱, K۳, Y۲, T۵, Y۳, T۳, T۱, Y۱ (Figure ۱) and fungal isolatesY۳C, T۱F of (Figure ۲) formed biofilms and degraded PET films.Results: Result and Discussion: According to the SEM images, bacterial isolates K۲, T۲, K۱, K۳, Y۲, T۵, Y۳, T۳, T۱, Y۱ (Figure ۱) and fungal isolatesY۳C, T۱F of (Figure ۲) formed biofilms and degraded PET films.Conclusion: Conclusion: It seems that Actinomycetes are capable of PET degradation and further study of their mode of action via degrading enzymes can be useful. Figure ۱: Growth of samples on PET film after ۷۰ days: a:K۲,b:T۲, c:K۱, d:K۳, e:Y۲, f:T۵, g:Y۳, h:T۳, i:T۱, j:Y۱, k:Y۳c, l:T۱F, m:blank