Identification of novel polyethylene-degrading fungi from South African landfill soils: Arthrographis kalrae, Lecanicillium coprophilum, and Didymosphaeria variabile.

The persistent inefficiency of landfill operations and plastic waste management in South Africa has intensified environmental contamination, underscoring the urgent need for innovative bioremediation strategies. This study aimed to identify and evaluate fungal isolates from landfill soils for their ability to biodegrade polyethylene (PE), thereby contributing to sustainable plastic waste management solutions. A total of eighteen fungal isolates were recovered from local landfill soils using plastic-enriched soil dilution techniques. These isolates were screened for PE biodegradation by incubating pre-weighed polyethylene strips with each fungal culture for 45 days at ambient temperature. Biodegradation efficiency was assessed through gravimetric weight loss, while structural alterations in the polymer matrix were examined using fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Several isolates demonstrated significant PE degradation, including the novel PE degraders Arthrographis kalrae SP5INT, Lecanicillium coprophilum SP7MK, and Didymosphaeria variabile SP11INT, reported here for the first time. Penicillium chrysogenum SP17MK and Engyodontium album SP3MK showed the highest degradation rates, achieving over 20% weight loss. FTIR analysis revealed the appearance of carbonyl groups (~ 1700 cm⁻¹) and a reduction in characteristic PE peaks at 719 and 1472 cm⁻¹, suggesting oxidative degradation. SEM imaging further confirmed surface erosion and structural disintegration of the polymer, supporting the biochemical evidence of degradation. These findings represent the first report of novel fungal species capable of degrading PE in South African landfill soils and significantly expand the known diversity of plastic-degrading fungi. This work highlights South Africa's emerging role in microbial bioremediation research and provides a foundation for the development of locally relevant, biologically based plastic waste management strategies.