Degradation of scrapie infected brain homogenateby a novel bacterial keratinase

Prion protein is central to Transmissible Spongiform Encephalopathy (TSE) pathogenesis. Characteristically prion is resistant to conventional methods of sterilization and the most effective means of its degradation are incineration and alkaline hydrolysis. These methods are limited by environmental acceptability, application compatibility, cost and loss of reusable materials. Enzymatic degradation provides a viable alternative for decontaminating animal carcasses, specified risk materials, as well as surgical and dentistry instruments. The objective of this research was to isolate and characterise microbial keratinases and to investigate their ability to degrade keratinaceous materials and possibly scrapie prions. Microbial isolates from farmyard waste were grown on feather meal medium and the synthesised keratinase characterised by MALDI-MS and SDS-PAGE. Keratinolytic activity was determined using keratin azure, casein and melanised feather as substrates. Degradation of scrapie prion was evaluated by western blotting analysis. One specific isolates, identified as a strain of Bacillius licheniformis, demonstrated considerable promise. The molecular weight of the enzyme produced by this bacteria was found to be ≈28KDa, with optimum pH and temperature at 8.0 and 50 °C respectively. This novel keratinase demonstrated significant activity on keratin azure (11 U/mL) and casein substrates, and completely degraded melanised feather within 48h. Western blotting analysis shows significant reduction in prion signal and immunoreactivity for scrapie infected mouse (ME7) brain homogenate after incubation with this keratinase. Inclusion of a biosurfactant also further enhanced degradation of scrapie prion. The ability of this novel bacterial keratinase to degrade keratin materials and scrapie prion suggests its potential use as an environmental alternative in prion decontamination and other applications.