Single-use plastics are essential but cause significant environmental issues, particularly due to inadequate recycling. The large-scale production of plastic, its long lifetime, and its pollution due to landfilling necessitate the development of new, more sustainable,and more effective recycling strategies. Polyolefins like polyethylene (PE) and polypropylene (PP), are very inert to biodegradation and chemical recycling. Most current chemical recycling methodologies rely on high-energy processes or require harsh conditions like high temperatures or toxic chemicals. Especially the generation and distribution of microplastic represent a growing environmental problem and require alternative methodologies for its degradation. One possibility for the degradation of polyolefin microplastic is photoinduced oxidative degradation. Photocatalysts like TiO2 accelerate the formation of hydroxyl radical (HO•), a reactive oxygen species (ROS),which is a powerful oxidant that initiates the degradation of polyolefins.In this study we explored a novel bio-based approach for PE degradation using light drivenprotein-based photocatalysts that create ROS upon visible light exposure,promoting the oxidative degradation of PE. Different photosensitizing proteins (PSPs)were analyzed, regarding their ROS-producing activity. Two representatives of LOV (lightoxygen-voltage-sensing) domain proteins, which harbor a blue-light sensitive flavinchromophore, were selected. Due to the short lifetime of ROS, efficient adsorption of the LOV protein to the hydrophobic polyolefin surface would improve oxidation efficiency. Apreviously reported concept was implemented, where different hydrophobins (smallfungal proteins containing a hydrophobic patch) were fused to the LOV proteins.Therefore, different genetic constructs encoding the fusion proteins were created by molecular cloning. Fusion proteins were produced in Escherichia coli and purified by immobilized metal affinity chromatography (IMAC).Improved adsorption of the fusion proteins to a PE/PP surface was proven by different surface analysis methods. Among these, water contact angle measurement (WCA) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) resulted to be the most suitable methods. In this context, protocols for the generation of smooth polymer surfaces by spin coating were developed. Besides the analysis of the adsorption behavior of the fusion proteins, the stability of the fusion proteins towards blue light was analyzed by fluorescence and oxygen consumption measurements. Moreover, ROS specificassays (including HO•, 1O2, H2O2, and O2•-) were conducted for the evaluation of ROS production by the fusion proteins. The LOV protein DsFbFpM49I (Dinoroseobactershibae) fused to the hydrophobin mHGF1 (Grifola frondosa) showed the highest ROSproduction.For the verification of in situ generation of HO• by the protein on a polyolefin surface, a HO• specific assay was incorporated into a PE layer. The production of HO• directly on the PE surface by the adsorbed fusion protein could be proven, while with solubilizedprotein no HO• production could be detected.Finally, the concept that the protein is capable of oxidative polyolefin degradation was proven. A degradation experiment was conducted with the fusion protein mHGF1-xiDsFbFpM49I and commercially available PE. A positive control for the oxidation of the PEsurface (with Fenton’s reagent) was conducted. The oxidation of the PE surface was analyzed by ATR-FTIR, laser-induced breakdown spectroscopy (LIBS), and X-rayphotoelectron spectroscopy (XPS). Surface-bound oxygen could be detected,suggesting surface oxidation by the protein.