Fifteen-Year Application of Manure and Chemical Fertilizers Differently Impacts Soil ARGs and Microbial Community Structure

Manure as a Potential Hotspot for Antibiotic Resistance Dissemination by Horizontal Gene Transfer Events

“…The use of antibiotics during animal growth favors the appearance of antibiotic-resistant bacteria in the gut microbiota, which consequently may be released within feces and be disseminated by manure application [30]. The application of organic fertilizers, as well as inorganic fertilizers to a less extent, has been shown to impact the soil microbial community and it is the major driver of the shaping of the antibiotic resistome [36,37].…”

“…A strong correlation between the high use of certain antibiotics in livestock (and their residues) and the presence of ARGs and MGEs, such as plasmids, integrative conjugative elements, transposons and integrons, involved in the spread of ARGs via HGT pathways from manure to soil microbes, has been found [38][39][40]. ARGs and MGEs, especially integrons and transposons, in manure have been showed to be closely related, and their increased abundance is related to manure application [24,37]. Manure has a higher impact on the abundance and diversity of ARGs in soil than chemical fertilizers [37].…”

“…ARGs and MGEs, especially integrons and transposons, in manure have been showed to be closely related, and their increased abundance is related to manure application [24,37]. Manure has a higher impact on the abundance and diversity of ARGs in soil than chemical fertilizers [37].…”

“…In addition to the antibiotic administration patterns [49], feed administration, exposure to heavy metals, animal age, time and manure nitrogen content may all contribute to the ARG content in manure [24,46,48]. The major concern about the presence of ARGs in manure is the possibility of their transfer to the soil bacteria via HGT mechanisms, which can promote the spread of antimicrobial resistance among different microbial communities [30,37,48]. In this context, it is important to understand the differences in the content of antibiotic-resistant bacteria and ARGs in soils in response to manure application.…”

“…After a one-time manure application, persistence times in soil vary among different ARGs [48]. However, ARGs are stable in the microbial community of a soil that regularly receives manure applications [36,37,52].…”