Abstract：
Polyethylene terephthalate (PET) is widely used for various industrial applications. However, owing to its extremely slow breakdown rate, PET accumulates as plastic trash, which negatively affects the environment and human health. Here, we report two novel PET hydrolases: PpPETase from Pseudomonas paralcaligenes MRCP1333, identified in human feces, and ScPETase from Streptomyces calvus DSM 41452. These two enzymes can decompose various PET materials, including semicrystalline PET powders (Cry-PET) and low-crystallinity PET films (gf-PET). By structure-guided engineering, two variants, PpPETaseY239R/F244G/Y250G and ScPETaseA212C/T249C/N195H/N243K were obtained that decompose Cry-PET 3.1- and 1.9-fold faster than their wild-type enzymes, respectively. The co-expression of ScPETase and mono-(2-hydroxyethyl) terephthalate hydrolase from Ideonella sakaiensis (IsMHETase) resulted in 1.4-fold more degradation than the single enzyme system. This engineered strain degraded Cry-PET and gf-PET by more than 40% and 6%, respectively, after 30 d. The concentrations of terephthalic acid (TPA) in the Cry-PET and gf-PET degradation products were 37.7% and 25.6%, respectively. The discovery of these two novel PET hydrolases provides opportunities to create more powerful biocatalysts for PET biodegradation.
摘要：
聚对苯二甲酸乙二醇酯(PET)广泛用于各种工业应用。然而,由于其故障率极其缓慢，PET积聚成塑料垃圾，这会对环境和人类健康产生负面影响。这里,我们报道了两种新的PET水解酶：在人类粪便中鉴定的副产碱假单胞菌MRCP1333的PpPETase，和ScPETase来自小牛链霉菌DSM41452。这两种酶可以分解各种PET材料，包括半结晶PET粉末(Cry-PET)和低结晶度PET薄膜(gf-PET)。通过结构引导工程，两种变体,获得了PpPETaseY239R/F244G/Y250G和ScPETaseA212C/T249C/N195H/N243K，它们分解Cry-PET的速度比野生型酶快3.1和1.9倍，分别。ScPETase和sakaiensis的单（2-羟乙基）对苯二甲酸酯水解酶（IsMHETase）的共表达导致的降解比单酶系统多1.4倍。该工程菌株将Cry-PET和gf-PET降解超过40％和6％，分别,30d后。Cry-PET和gf-PET降解产物中对苯二甲酸（TPA）的浓度分别为37.7%和25.6%，分别。这两种新型PET水解酶的发现提供了产生用于PET生物降解的更强大的生物催化剂的机会。
