Development of a novel "4E" polyethylene terephthalate bio-recycling process with the potential for industrial application: Efficient, economical, energy-saving, and eco-friendly

Recently, clean PET biodegradation has gained widespread attention in tackling white pollution. Nonetheless, the development of industrial biotechnology is still impeded by its contamination susceptibility, high energy input, and consumption of substantial freshwater resources. Thus, a novel PET biodegradation process was developed based on host screening and by-product circulation to address the aforementioned issues. The fastgrowth host halophilic Vibrio natriegens (V. natriegens) was used and exhibited an increased protein expression level of 87.3% compared to E. coli. Meanwhile, the new process utilized a seawater-based medium for fermentation under non-sterile conditions, leading to energy-saving (energy reduced by 2.48-fold) and cost-reduction (cost reduced by 47.9%). Moreover, the large amount of saline wastewater from terephthalic acid purification was ingeniously reused for the cultivation of V. natriegens, thereby avoiding resource wastage and secondary pollution. Therefore, an efficient, economical, energy-saving, and eco-friendly process was designed, potentially addressing the industrial bottleneck in PET bio-recycling.