Download the full-sized PDF of Composting as a method for disposal of specified risk material and degradation of prionsDownload the full-sized PDF



Permanent link (DOI):


Export to: EndNote  |  Zotero  |  Mendeley


This file is in the following communities:

Graduate Studies and Research, Faculty of


This file is in the following collections:

Theses and Dissertations

Composting as a method for disposal of specified risk material and degradation of prions Open Access


Other title
Bovine spongiform encephalopathy
Specified risk material
Chronic wasting disease
Greenhouse gas emission
Type of item
Degree grantor
University of Alberta
Author or creator
Xu, Shanwei
Supervisor and department
Leonard, Jerry (Agricultural, Food and Nutritional Science)
Examining committee member and department
McAllister, Tim (Agriculture and Agri-Food Canada)
Guan, Leluo (Agricultural, Food and Nutritional Science)
Neumann, Norman (School of Public Health)
Ghaly, Abdel (Dalhousie University)
Belosevic, Miodrag (Biological Sciences)
Department of Agricultural, Food, and Nutritional Science
Bioresource and Food Engineering
Date accepted
Graduation date
Doctor of Philosophy
Degree level
Provided that infectious prions (PrPTSE) are inactivated, composting of specified risk material (SRM) may be a viable alternative to rendering and land filling. The overall objective of this research was to utilize laboratory-scale composters to assess the degradation of SRM and PrPTSE during composting. Under non-containment conditions, co-composting of SRM with cattle manure revealed that SRM was degraded rapidly in compost, with approximately 60% and 80% dry matter loss after 14 and 28 days, respectively. Composter depth, types of bulking agent, or prolongation of thermophilic temperature using a water jacket did not influence SRM degradation. However, mixing of feathers with manure increased the extent of SRM degradation. Phospholipid fatty acid (PLFA) profiles demonstrated that both mesophilic and thermophilic microbial communities were responsible for SRM degradation. Furthermore, PCR-denaturing gradient gel electrophoresis (DGGE) analysis suggested that bacterial genera of Thermoactinomycetaceae, Thiohalospira, Pseudomonas, Enterobacter, Corynebacterium, Promicromonospora, Pseudonocardia, Thermobifida, Mycobacterium, Nocardia, Saccharomonospora, Streptomyces, Actinomadura, and fungal genera of Dothideomycetes, Cladosporium, Chaetomium, and Trichaptum may play a role in SRM degradation in compost. Prior to and after 14 or 28 days of composting, PrPTSE was detected by Western blotting (WB) after extraction using sodium dodecyl sulphate (SDS) and sodium phosphotungstic acid (PTA) precipitation. The WB findings suggested at least 1-2 log10 reduction of PrPTSE signals after 14 to 28 days of composting. Although scrapie prions (PrPSc) degradation can not be definitively concluded, the disappearance of chronic wasting disease prions (PrPCWD) and bovine spongiform encephalopathy prions (PrPBSE) may reflect biological degradation in compost. This is the first study to investigate possible biological degradation of PrPCWD and PrPBSE during composting, suggesting that it has merit as a means of SRM disposal.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Xu, S., McAllister, T.A., Leonard, J.J., Clark, O.G. and Belosevic M. 2010. Assessment of microbial communities in decomposition of specified risk material using a passively aerated laboratory-scale composter. Compost Science & Utilization. 18(4): 255-265.Xu, S., Inglis, G.D., Reuter, T., Clark, O.G., Belosevic, M., Leonard J.J. and McAllister, T.A. 2011. Biodegradation of specified risk material and characterization of actinobacterial communities in laboratory-scale composters. Biodegradation. 22(5): 1029-1043.

File Details

Date Uploaded
Date Modified
Audit Status
Audits have not yet been run on this file.
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 2413082
Last modified: 2015:10:12 18:36:59-06:00
Filename: Xu_Shanwei_Fall 2012.pdf
Original checksum: 328dffc1c2d2c80758aaf2b0ffa9c49b
Well formed: true
Valid: true
Page count: 277
File language: en-CA
Activity of users you follow
User Activity Date