Antibiotic and antibiotic-resistant gene loads in swine slurries and their digestates: Implications for their use as fertilizers in agriculture

Impact of organic soil amendments in antibiotic levels, antibiotic resistance gene loads, and microbiome composition in corn fields and crops

“…We conclude from these two lines of evidence that there was an impact of a repeated use of fertilizers in two consecutive harvest cycles. A similar temporal trend was observed in experimental orchards fertilized with either organic or mineral fertilizers, as ARG total loads, ARG profiles and ASV distribution among soil samples depended on the time elapsed between fertilization and sampling (Sanz et al, 2021).…”

“…ARG loads in soils appeared linked mostly to the orders Micrococcales and Bacillales for the first harvest cycle, and intI1 and sul1 to the orders Micromonosporales, Clostridiales, Polyangiales and to the Gamma-Proteobacteria orders Steroidobacterales and Pseudomonadales for the second harvest cycle. Some of these groups were also found linked to high ARGs loads in fertilizers (Sanz et al, 2021) and to high ARG prevalence in soils, plants, and fruits (Cerqueira et al, 2019b;Fogler et al, 2019). The data also showed higher levels of intI1 and sul1 and higher diversification of the microbiomes for the soils of the second cycle relatively to the first-cycle soils, and that the type of fertilizer was only determinant in the ASV distribution for the second cycle samples.…”

“…More than a direct cause-relationship between AB and ARG levels in soils, we consider these coincidences as an indicator of a higher impact of this fraction in soils relative to digested fertilizers, liquid fraction, or even to the raw slurry. Our current hypothesis is that these levels correspond to the selective pressure occurring either in the pig guts or, less likely, in the decantation ponds, as revealed by the very high loads of intI1, sul1, tetM, and Tetracyclines we find in fertilizers derived from pig slurry (Sanz et al, 2021), this paper).…”

“…Organic fertilizers, and particularly those originated from animal farm slurry, present high levels of pharmaceuticals (including antibiotics), antibiotic resistant bacteria and ARGs, partially due to illcontrolled pharmaceutical treatments of animals (Sanz et al, 2021). This presence should be taken into consideration on the use of these potentially very advantageous source of nutrients in agriculture, and should promote the setting of legal requirements regarding the intensity and timing of their application.…”

Anaerobic Digestion and Removal of Sulfamethoxazole, Enrofloxacin, Ciprofloxacin and Their Antibiotic Resistance Genes in a Full-Scale Biogas Plant

“…Because manure is commonly used as feed for anaerobic digesters, the possible presence and fate of antibiotic resistant genes (ARGs) in the AD process needs to be better investigated [ 13 , 14 ]. The presence of antibiotics in digesters might lead to antibiotic resistant bacteria (ARBs) and ARGs in digestate and subsequently in soil if the digestate is used as a fertilizer [ 15 ].…”