## 1 Introduction  
Cutinase-like enzymes are gaining interest because some exhibit degradation activity on polyethylene terephthalate (PET). Since the first report on a PET-active cutinase was published in 2005 [1], reports on PET-depolymerizing enzymes have significantly increased in recent years, after the publication of the _Ideonella sakianensis_ bacterium that was able to grow using PET as the sole carbon source [2]. It is worth emphasizing that the amorphous domain of PET can be more accessible to an enzyme attack than crystalline domains. Indeed, thermostabilized PETase, acting at temperatures closer to the glass transition temperature of PET, has shown a better depolymerizing performance [3]. However, mesophilic enzymes and microorganisms could play an important role in the systems where high temperatures are not suitable, such as in wastewater plants. The annual production of plastics was estimated to be 348 million tons in 2017, of which \(\sim\)90% was derived from fossil fuels [4; 5]. By 2030, it is expected to increase to 590 million tons [6]. Owing to their expanding use and versatility, plastic products have become a part of everyday life [7]. Polyethylene terephthalate (PET) consists of ethylene glycol (EG) and terephthalatic acid (TPA) monomers linked by ester bonds. It is considered one of the most widely used synthetic polymers and has many applications in drinking bottles, food packaging, and textile fiber materials [8; 9]. In 2017, PET production exceeded 30 million tons. Packaging materials always rank high, accounting for \(\sim\)40% of the total plastics produced [4]. They accumulate in urban solid waste, landfills, and oceans, causing global environmental pollution [10]. This situation has caused severe damage to marine life and threatened some species as most plastic waste on land ends up in water bodies [11]. Plastics are recalcitrant materials for biological degradation. However, 30,000 non-redundant enzyme homologs with putative activity in 10 different plastic types were recently found using bioinformatics methods [12], supporting the current trend of developing enzymatic processes for plastic recycling. Nevertheless, only a small number of fungi and bacteria capable of partially depolymerizing PET have been experimentally studied [13]. The crystallinity of PET is one of the main obstacles to its biodegradation. The enzymes that hydrolyze PET are serine hydrolases, such as cutinases, lipases, and carboxylesterases. The _I. sakianensis_ enzyme, PETase (PET-active enzyme), mainly produces mono(2-hydroxyethyl) terephthalatic acid (MHET) and, to a lesser extent, terephthalatic acid (TPA) and bis(2-hydroxyethyl)-TPA [2]. The cutinases are part of the \(\alpha/\beta\) family of serine hydrolases that perform ester bond hydrolysis using the canonical Ser-His-Asp catalytic triad. PET and cutin generally share small structural features; they have ester bonds that can be cleaved by cutinases [14; 15]. Plastic pretreatment is an important process before enzymatic depolymerization. Plastic crystallinity is one of the main obstacles to an enzymatic attack [16]. Therefore, several pretreatment strategies focus on increasing the amorphization. For example, extrusion and micromization are processes widely used in the plastic industries that amorphize and increase the exchange surface of plastics, facilitating an enzymatic attack. These technologies have maximized PET depolymerization by using an outperforming engineered leaf-branch compost cutinase (LCC), resulting in an outstanding depolymerization yield in a few hours [3]. At the laboratory level and for research purposes, as in this work, PET and other polyesters can also be dissolved in organic solvents and then precipitated as powders [17]. These polyester powders have a lower crystallinity and are suitable for assessing enzymatic activities. On the other hand, green plastic pretreatments should be developed for practical purposes and industrial processes.