Targeting microplastic particles in the void of diluted suspensions

  Photos of Shohana Islam and Lina Apitius Copyright: BioVI

Shohana Islam#, Lina Apitius#, Felix Jakob, and Ulrich Schwaneberg. 2019, Environ. Int. 123: 428-435. #shared co-authorship.

In the present publication, the application of the anchor peptide Tachystatin A2 as adhesion promoter is described, which enhances the degradation of polyester-polyurethane nanoparticles by the cutinase Tcur1278.

  Field emission scanning electron microscopic image of microplastic degradation by cutinases Copyright: Environ. Int. Field-scanning electron micrograph of the enzymatic degradation of polyester-polyurethane after 24 h. Only when treated with the cutinase anchor fusion protein is a degradation of the material to visible..

The accumulation of microplastics in the environment as well as in the food chain will be a grand upcoming challenge for our society. Polyurethanes belong to the accumulating plastics as they are widely used in medical, e.g. catheters, and industrial products, especially as foams. Polyurethane is a man-made polymer and therefore not abundant in nature. Hence, only a few fungal and microbial strains as well as enzymes, such as polyurethaneases and cutinases, have been reported to efficiently degrade polyurethane. An estimated degradation of plastic in nature takes at least 50 to 100 years. A minimization of existing environmental pollution requires sustainable management strategies for microplastics. Material binding peptides like anchor peptides strongly bind to synthetic polymers such as polypropylene, polyethylene terephthalate, and polyurethane. In this publication, we report the fusion of the anchor peptide Tachystatin A2 to the bacterial cutinase Tcur1278. The fusion enzyme Tcur1278-Tachystatin A2 accelerated the degradation of polyester-polyurethane nanoparticles by a factor of 6.6 in comparison to wild-type Tcur1278 without any anchor peptide. Additionally, the degradation half-life of polyester-polyurethane nanoparticles was reduced from 41.8 h to 6.2 h indicating a 6.7-fold improvement in a highly diluted polyester-polyurethane suspension by the fusion enzyme. Taken together, anchor peptides provide a versatile tool for a targeted degradation of micro- and nanoplastics at ambient temperature in highly diluted particle suspensions.

This work was financed by the German Federal Ministry of Education and Research and the German Federation of Industrial Research Associations. We acknowledge Prof. Wolfgang Zimmermann and Dr. Ren Wei for the sequence of the cutinase Tcur1278. We thank Thorsten Palmer for dynamic light scattering measurements and finally the Center for Chemical Polymer Technology especially Sabrina Mallmann for field emission scanning electron microscopy.