Biodegradation of specified risk material and fate of scrapie prions in compost

Abstract

Composting may be a viable alternative to rendering and land filling for the disposal of specified risk material (SRM) provided that infectious prion proteins (PrP(TSE)) are inactivated. This study investigated the degradation of SRM and the fate of scrapie prions (PrP(Sc)) over 28 days in laboratory-scale composters, with and without feathers in the compost matrices. Compost was mixed at day 14 to generate a second heating cycle, with temperatures exceeding 65°C in the first cycle and 50°C in the second cycle. Approximately 63% and 77% of SRM was degraded after the first and second cycles, respectively. Inclusion of feathers in the compost matrices did not alter compost properties during composting other than increasing (P < 0.05) total nitrogen and reducing (P < 0.05) the C/N ratio. However, addition of feathers enhanced (P < 0.05) SRM degradation by 10% upon completion of experiment. Scrapie brain homogenates were spiked into manure at the start of composting and extracted using sodium dodecyl sulphate followed by detection using Western blotting (WB). Prior to composting, PrP(Sc) was detectable in manure with 1-2 log(10) sensitivity, but was not observable after 14 or 28 days of composting. This may have been due to either biological degradation of PrP(Sc) or the formation of complexes with compost components that precluded its detection.

Can plants serve as a vector for prions causing chronic wasting disease?

“…4). 21 It should be noted that 1% SDS extracted protein less efficiently than the extraction kit and likely lowered our detection limit in plant tissue as demonstrated by the decreased intensity of cross-reaction bands in the root and stem (Fig. 4).…”

“…When considering the strong interaction between recombinant PrP C and the roots, it is worth noting that this prion protein is also N-terminally truncated as compared with mammalian PrP C (Fig. 1) 21 an outcome that may increase its interaction with plant roots.…”

Impacts of sporulation temperature, exposure to compost matrix and temperature on survival of Bacillus cereus spores during livestock mortality composting

“…) and prions associated with diseases such as scrapie (Xu et al . ), which like bacterial spores are known for their resistance to thermal, chemical and enzymatic degradation (Franke‐Whittle and Insam ).…”

Microbial keratinases: characteristics, biotechnological applications and potential.

“…A thermophilic condition and alkaline environment is highly conducive for microbial keratinase activity (see section 5.1 5.1). A number of studies have demonstrated biodegradation of prion protein using compost (Huang et al 2007;Xu et al 2013). In a field trial, Xu et al (2014) also observed that composting reduced PrP TSE , resulting in one 50% infectious dose (ID50) remaining in every 5,600 kg of final compost for land application.…”