Fungal Enzymes as Catalytic Tools for Polyethylene Terephthalate (PET) Degradation

Abstract

The ubiquitous persistence of plastic waste in diverse forms and different environmental matrices is one of the main challenges that modern societies are facing at present. The exponential utilization and recalcitrance of synthetic plastics, including polyethylene terephthalate (PET), results in their extensive accumulation, which is a significant threat to the ecosystem. The growing amount of plastic waste ending up in landfills and oceans is alarming due to its possible adverse effects on biota. Thus, there is an urgent need to mitigate plastic waste to tackle the environmental crisis of plastic pollution. With regards to PET, there is a plethora of literature on the transportation route, ingestion, environmental fate, amount, and the adverse ecological and human health effects. Several studies have described the deployment of various microbial enzymes with much focus on bacterial-enzyme mediated removal and remediation of PET. However, there is a lack of consolidated studies on the exploitation of fungal enzymes for PET degradation. Herein, an effort has been made to cover this literature gap by spotlighting the fungi and their unique enzymes, e.g., esterases, lipases, and cutinases. These fungal enzymes have emerged as candidates for the development of biocatalytic PET degradation processes. The first half of this review is focused on fungal biocatalysts involved in the degradation of PET. The latter half explains three main aspects: (1) catalytic mechanism of PET hydrolysis in the presence of cutinases as a model fungal enzyme, (2) limitations hindering enzymatic PET biodegradation, and (3) strategies for enhancement of enzymatic PET biodegradation.

Fungal Enzymes Involved in Plastics Biodegradation

“…This technique enhances catalytic activity and increases the stability, specificity and selectivity of the immobilized enzymes, thus significantly reducing production costs [242]. A number of studies have reported that the immobilisation of PET-degrading bacterial enzymes enhances their catalytic activity and thermal stability [243][244][245], but few studies have focused on fungi [246]. Su et al [247] immobilised cutinase from Aspergillus oryzae, Humicola insolens and Thielavia terrestris on the macroporous support Lewatit VP OC 1600 obtaining immobilization yields higher than 98%.…”

Waist-to-height ratio assessment device

“…It is a portable device with a rechargeable battery that can be taken anywhere. The case is 3D printed and the material used was a glycolmodified version of polyethylene terephthalate (PET), which is a lightweight and strong plastic [18], [19]. The The waist and height of twenty (20) individuals composed of ten (10) males and ten (10) females were used to test the features of the device.…”

The Use of Mycelial Fungi to Test the Fungal Resistance of Polymeric Materials

“…This transparent, durable, and lightweight plastic is widely used for packaging, including disposable drink bottles. The fungi of the genera Aspergillus , Fusarium , and Humicola [ 43 ] are involved in its degradation in nature.…”