Effectiveness of Windrow Composting Methodology in Killing a Thermo-Tolerant Species of Salmonella During Mortality Composting

<p>In a large agricultural operation, such as the one at Cal Poly San Luis Obispo, disposal of deceased animals is an immense issue. The cost of transporting and rendering every dead animal is inhibitory to the general function of the agricultural operations and their thin budget. Therefore, we propose that composting mortalities could be an economical alternative. Composting is a recognized method for taking animal waste products along with carbon waste and turning it into a pathogen-free, nutrient-rich topsoil. Carcass composting is in fact performed in other countries and states to varying degrees of success. However, the California EPA limits carcass composing to only private land. Therefore, the purpose of this work was to determine the efficacy of killing pathogens by composting using bench top composting models. Ultimately, our goal is to provide “proof of concept” data in order to gain permission for a full-scale carcass compost pile to be set up at Cal Poly San Luis Obispo.</p> <p>Using thermo tolerant <em>Salmonella senftenberg </em>as an indicator organism, we performed bench top trials of traditional and carcass compost in the lab. Samples were inoculated with <em>S. senftenberg </em>and kept at 55°C for 15 days in accordance with the California EPA and Test Method for the Examination of Composting and Compost (TMECC). Samples were then plated and processed for multiple tube analysis and most probable number. Samples were also partitioned for a viability qPCR with propidium monoazide (PMA) to compare to the classic techniques. Using these methods we were then able to track and produce thermal death time data for <em>S. senftenberg </em>in both traditional and carcass compost. By comparing the types of compost, we were able to determine that the composting method presented by the California EPA and the TMECC produces safe, pathogen free compost, even when inoculated carcasses were introduced. However, even with removal of dead cells by PMA, qPCR did not outperform the classical microbiological methods for as tracking pathogen killing.</p>

Name thesis:degree_name

MS in Biological Sciences

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2019

Author dc:creator

• Myers, Spencer Gabriel

Contributors dc:contributor

• Pat Fidopiastis

• Compost
• Mortality Compost
• Salmonella
• Biosecurity
• Environmental Microbiology and Microbial Ecology
• Microbial Physiology
• Microbiology
• Other Microbiology
• Pathogenic Microbiology
• Soil Science
• Sustainability

Identifier

10.15368/theses.2018.155

OAI identifier oai:identifier

oai:digitalcommons.calpoly.edu:theses-3356