A comparison of antibiotic resistance genes from animal and human waste-based fertilizers: A case for changing farming practices?
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Date
2022-08-14
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Other Conference Item
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yes
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Abstract
Human excreta-derived fertilizers contribute to sustainable agriculture by reusing valuable nutrients. However, consumer prejudice, farmer hesitance and strict regulations discourage utilization of these fertilizers, while animal manure is widely accepted. Yet, both fertilizers may contain antibiotics and antibiotic resistance genes which spread among soil microorganisms by horizontal gene transfer. Here, we conducted a meta-analysis to compare antibiotic resistance gene presence, abundance and diversity in human excreta-derived fertilizers and animal manure.
We created a co-occurrence keyword network using the litsearchr R package to find suitable papers and reduce bias. We collected data such as the antibiotic resistance gene determination method, fertilizer base (human or animal), fertilizer type (i.e. manure, sewage sludge), and assessed antibiotic resistance genes. This resulted in 7918 datapoints from 43 papers on human excreta-derived fertilizers, 7558 datapoints from 24 papers on animal manure and 3321 datapoints of untreated soil from 14 papers.
Antibiotic resistance genes were most often detected in soil amended with animal manure (91.1%), followed by animal manure directly (81.6%), human excreta-derived fertilizers directly (68.2%), soil amended with human excreta-derived fertilizers (45.2%) and lastly in untreated soil (35.1%). Moreover, antibiotic resistance gene diversity was highest in animal manure, compared to human excreta-derived fertilizers and untreated soil. Animal manure and human excreta-derived fertilizers soil amendments added, respectively, 70 and 28 unique antibiotic resistance genes that were not detected in untreated soil.
Our results indicate that, in the context of the soil resistome, human excreta-derived fertilizers are a safe alternative to animal manure. However, studies covering a larger diversity of soil and environmental settings are needed to better understand antibiotic resistance gene dissemination and to identify safe application rates for using human excreta as fertilizer.
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ETH Zurich, Institute of Terrestrial Ecosystems
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18th International Symposium on Microbial Ecology (ISME 2022)
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Subject
microbial ecology; antibiotic resistance; antibiotics; Sustainable agriculture; human excreta-derived fertilizers; animal excreta-derived fertilizers
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09646 - Dötterl, Sebastian / Dötterl, Sebastian
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Funding
193118 - Understanding the impacts of antibiotics from human excreta derived fertilizers on the soil-microbial-plant nexus (SNF)