|GURMESSA, BIYENSA - Polytechnic University Of Marche|
|MILANOVI, VESNA - Polytechnic University Of Marche|
|PEDRETTI, ESTER - Polytechnic University Of Marche|
|AQUILANTI, LUCIA - Polytechnic University Of Marche|
|CORTI, GIUSEPPE - Polytechnic University Of Marche|
|COCCO, STEFANIA - Polytechnic University Of Marche|
|FERROCINO, ILARIO - University Of Turin|
|CORVAGLIA, MARIA - University Of Turin|
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2021
Publication Date: 8/6/2021
Citation: Gurmessa, B., Milanovi, V., Pedretti, E.F., Aquilanti, L., Corti, G., Cocco, S., Ashworth, A.J., Ferrocino, I., Corvaglia, M.R. 2021. Post-digestate composting shifts microbial composition and degrades antimicrobial resistance genes. Bioresource Technology. 340. Article 125662. https://doi.org/10.1016/j.biortech.2021.125662.
Interpretive Summary: Anaerobic digestion turns organic waste, such as crop residue and animal manure into electricity via fermentation and may also minimize the occurrence of antibiotic resistance genes in the byproduct, which may be used as a soil amendment to improve soil fertility. However, it is expected that changes in the compositing conditions may affect the microbiological communities and in turn impact soil amendment quality and antibiotic resistant gene occurrence. Researchers in the U.S. and Italy evaluated the abundance of antibiotic resistant genes following composting of this byproduct and found that more than 75% of antibiotic resistance genes were removed after 90 days of composting. Overall, this study found that composting can be an effective strategy for removing antibiotic resistant genes in this byproduct. Therefore, this study identified a novel composting process for reducing the amount of antibiotic resistant genes released in to the soil-water environment while providing a bioenergy source and a valuable soil amendment.
Technical Abstract: Anaerobic digestion has been recognized for its inefficiency to reduce the prevalence of antibiotic resistant genes (ARGs) from agricultural wastes, however, post-digestate treatments have been suggested to reduce the risk of ARGs release with digestate use. This study aimed to evaluate post-digestate composting effects on the abundance of the gene erm(B), encoding for resistance to macrolide-lincosamide-streptogramin B and the genes tet(K), tet(M), tet(O) and tet(S), encoding for resistance to tetracyclines. Large quantities of all ARGs were found in digestate and more than 75% were removed after 90 days of composting with relatively lower removal rates for erm(B). Bacteroidetes, Firmicutes, and Proteobacteria dominated fresh digestate and a network analysis indicated they were potential hosts of ARGs in feedstock. Canonical correspondence analysis showed more than 90% variations in ARGs abundance were explained by water extractable trace elements, suggesting a strong co-occurrence.