Screening for potent Polyethylene terephthalate (PET) degrading fungi: optimization of lipase production media and assessment of PET fabric waste degradation

Abstract

The escalating environmental impact of polyethylene terephthalate (PET) waste, particularly from synthetic fabrics, necessitates sustainable degradation strategies. This study focused on the screening of potent fungal isolates capable of degrading PET, with a specific emphasis on optimizing lipase production, a key enzyme involved in ester bond hydrolysis. The isolates were primarily screened for the production of PET degradation enzymes qualitatively and quantitatively. Among the screened isolates, PPS3 showed the highest PET fabric waste degradation efficiency of 13.6 ± 1.31% in quantitative screening. Based on 18S rRNA partial gene sequencing, this potent isolate was identified as Aspergillus niger and was utilized for further optimization and degradation experiments. Bioprocess variables influencing fungal lipase enzyme production were optimized through ‘One-factor-at-a-time’ (OFAT) approach. The optimized lipase production media was inoculated with the potent fungal isolate along with the PET waste and kept for 10 weeks of incubation. A weight loss of approximately 55 ± 2.38% was recorded, corresponding to the reduction in PET substrate mass, which demonstrates the degradation potential of the lipase enzyme. The PET degradation potential of the selected isolate was assessed through surface morphology changes (FESEM), and functional group modification (FTIR). Results demonstrated substantial PET fabric degradation, confirming the efficacy of the fungal strain and the importance of lipase in the biodegradation process. This study presents a promising biotechnological approach for mitigating PET pollution through microbial intervention and enzyme optimization.