Nylonase screening
Global production of synthetic polyamides (PA), or nylons, is increasing while recycling rates are currently below 5 % contributing to the global plastics crisis. Enzymatic depolymerization is a powerful strategy to overcome the drawbacks of mechanical and chemical recycling and has the potential to increase PA recycling rates. However, enzymatic depolymerization of PA is currently limited to a small group of nylonases (NylC) that exhibit low activities making them unsuitable for efficient enzymatic recycling. In this study, we extend the diversity of nylonases by library screenings and in silico analysis. Six novel nylonase candidates were successfully purified that showed varying sequence identities ranging from 84.2 % to 30.0 % towards the previously characterized NylCp2 from Paenarthrobacter ureafaciens. Activity of some nylonase candidates towards cyclic PA-oligomers and polymeric substrates was confirmed via the detection of soluble degradation products. These nylonases were also active on synthesized poly(ester-amides) (PEA), and this activity was synergistically increased by combination with the cutinase LCC. Overall, our discoveries greatly increase the input of NylC enzymes for future enzyme engineering strategies to boost their activities, and they show the potential of PEA for tuning the biodegradability of performance polymers. Thereby, this study leads the path for developing efficient enzymatic PA and PEA depolymerization processes, revealing significant insights into combining the contrary parameters of performance and biodegradability of polymers.
Global production of synthetic polyamides (PA), or nylons, is increasing while recycling rates are currently below 5 % contributing to the global plastics crisis. Enzymatic depolymerization is a powerful strategy to overcome the drawbacks of mechanical and chemical recycling and has the potential to increase PA recycling rates. However, enzymatic depolymerization of PA is currently limited to a small group of nylonases (NylC) that exhibit low activities making them unsuitable for efficient enzymatic recycling. In this study, we extend the diversity of nylonases by library screenings and in silico analysis. Six novel nylonase candidates were successfully purified that showed varying sequence identities ranging from 84.2 % to 30.0 % towards the previously characterized NylCp2 from Paenarthrobacter ureafaciens. Activity of some nylonase candidates towards cyclic PA-oligomers and polymeric substrates was confirmed via the detection of soluble degradation products. These nylonases were also active on synthesized poly(ester-amides) (PEA), and this activity was synergistically increased by combination with the cutinase LCC. Overall, our discoveries greatly increase the input of NylC enzymes for future enzyme engineering strategies to boost their activities, and they show the potential of PEA for tuning the biodegradability of performance polymers. Thereby, this study leads the path for developing efficient enzymatic PA and PEA depolymerization processes, revealing significant insights into combining the contrary parameters of performance and biodegradability of polymers.
Forschungszentrum Juelich