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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #333305

Research Project: Improvement of Soil Management Practices and Manure Treatment/Handling Systems of the Southern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Hydrothermal carbonization of livestock mortality for the reduction of pathogens and microbially-derived DNA

Author
item Ducey, Thomas
item Collins, Jessica
item Ro, Kyoung
item Woodbury, Bryan
item Griffin, D. Dee - University Of Nebraska

Submitted to: Frontiers of Environmental Science & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2017
Publication Date: 4/10/2017
Citation: Ducey, T.F., Collins, J.C., Ro, K.S., Woodbury, B.L., Griffin, D. 2017. Hydrothermal carbonization of livestock mortality for the reduction of pathogens and microbially-derived DNA. Frontiers of Environmental Science & Engineering. 11(3):9.

Interpretive Summary: Treatment of agricultural waste using high temperature and pressure (a process known as hydrothermal carbonization or HTC) has the potential to kill pathogens, degrade antibiotic resistance genes (ARGs), and destroy contaminants of emerging concern (CEC) in an environmentally and economically friendly manner. In this report we focused on a specific agricultural waste known as livestock mortality, which is the carcass of animals that have died on farm. While a number of methods are utilized to treat livestock mortality, there is little information on what happens to the deoxyribonucleic acid (DNA) during these treatment practices. This DNA, most notably ARGs, if it survives treatment can be reintroduced into agricultural environments where it could potentially be taken up by pathogens that may pose a risk to both animal and human populations. While HTC treatments have been shown to be effective in the treatment of CECs, very little is understood on how ARGs in livestock mortality survive HTC treatment conditions. This study aims to fill this knowledge gap by examining the survivability of microbially-mediated DNA in the treatment of livestock mortality by HTC. We examined three treatment temperatures (100 °C, 150 °C, and 200 °C) under high pressure at three residence times (30, 60, and 240 minutes), and examined the amplification of a mobile DNA element carried by Escherichia coli introduced to both beef bone and tissue. Results indicate that while all three temperatures and all three residence times were suitable for killing all pathogens, only temperatures of 150 °C and 200 °C were sufficient for eliminating microbially-derived DNA. These results serve as the basis for future potential HTC treatment recommendations for livestock mortality when considering the elimination of pathogens and ARGs.

Technical Abstract: Hydrothermal carbonization (HTC), utilizing high temperature and pressure, has the potential to treat agricultural waste and inactivate pathogens, antibiotic resistance genes (ARG), and contaminants of emerging concern (CEC) in an environmentally and economically friendly manner. Livestock mortality is one facet of agricultural waste that can pose a threat to the surrounding environment. While a number of methods are utilized to treat livestock mortality, there remains a paucity of data on the elimination of microbially-derived DNA in these treatment practices. This DNA, most notably ARGs, if it survives treatment can be reintroduced in agricultural environments where it could potentially be taken up by pathogens that may pose a risk to both animal and human populations. While HTC treatments have been shown to be effective in the treatment of CECs, very little is understood on how ARGs in livestock mortality survive HTC treatment conditions. This study aims to fill this knowledge gap by examining the survivability of microbially-mediated DNA in the treatment of livestock mortality by HTC. We examined three treatment temperatures (100 °C, 150 °C, and 200 °C) at autogenic pressures at three residence times (30, 60, and 240 minutes), and examined the amplification of a plasmidborne reporter gene carried by Ec introduced to both beef bone and tissue. Results indicate that while all three temperatures, at all three residence times, were suitable for complete pathogen kill, only temperatures of 150 °C and 200 °C were sufficient for eliminating microbially-derived DNA. These results serve as the basis for future potential HTC treatment recommendations for livestock mortality when considering the elimination of pathogens and ARGs.