Biodegradation of low-density polyethylene (LDPE) sheet

Plastic (polyethylene) pollution is a severe cause of deterioration of a healthy environment. For example, ingestion of plastics in the animal gut, clogging of water canals and retarded solid waste management. Many conventional methods of polyethylene degradation include UV photooxidation, thermal oxidation, incineration, chemical oxidation and landfill are being practiced. However, these methods are not feasible, costlier and not a complete solution for this global issue. Therefore, plausible, alternative solution for this issue is biodegradation. Microbes such as bacteria, fungi and algae are involved in polyethylene degradation in its natural habitat. Among them, algae were given very less importance. In our present study, a potential microalga, morphologically identified asUronema africanum Borge, isolated from a waste plastic bag collected from a domestic waste dumping site in a freshwater lake. This microalga was further treated with the LDPE sheet in BBM culture medium. Based on the results obtained from light microscopy, dark field microscopy, GC–MS, FT-IR, SEM and AFM, it was concluded that the microalga has initiated degradation of LDPE sheet within 30 days of incubation.

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Fig: (A) Topographical view of the Indian sub-continent showing all states and its borders, where the sample were taken from the state of Tamil Nadu (TN) situated down-south of India; (B) The image showing topographical view of the state TN, showing the sampling site in the city Chennai, present top North East of TN; (C) Figure showing the Chennai city, where the sampling site is located nearby Velachery town; (D) This image showing the exact sampling location (Longitude: 12°58′41.60″ North and Latitude: 80°14′08.43″ East) of Kallukuttai Lake, nearby Taramani Railway Station, Chennai, Tamil Nadu, India showing rapid urbanization on all the borders of the lake (Google Earth Pro 7.3.3.7699).

Concurrently, the cFonfiguration of corrosions, abrasions, grooves and ridges were found similar with the morphological features of the microalga. For example, the configuration of the radial disc-like attachment structure of the microalga was found corresponding to the abrasions on the surface of LDPE sheet at an average size of 20–30 µm in diameter. Whereas, the configuration of ridges and grooves were found similar with the filamentous nature of the microalga (10–15 µm width). This is a hitherto report on the biodegradation of LDPE sheet by the microalga Uronema africanum Borge.

Sanniyasi, E., Gopal, R.K., Gunasekar, D.K. et al. Biodegradation of low-density polyethylene (LDPE) sheet by microalga, Uronema africanumBorge. Sci Rep 11, 17233 (2021). https://doi.org/10.1038/s41598-021-96315-6

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