Fate and seasonality of antimicrobial resistance genes during full‐scale anaerobic digestion of cattle manure across seven livestock production facilities

Abstract

Anaerobic digestion has been suggested as an intervention to attenuate antibiotic resistance genes (ARGs) in livestock manure but supporting data have typically been collected at laboratory scale. Few studies have quantified ARG fate during full-scale digestion of livestock manure. We sampled untreated manure and digestate from seven full-scale mesophilic dairy manure digesters to assess ARG fate through each system. Samples were collected biweekly from December through August (i.e., winter, spring, and summer; n = 235 total) and analyzed by quantitative polymerase chain reaction for intI1, erm(B), sul1, tet(A), and tet(W). Concentrations of intI1, sul1, and tet(A) decreased during anaerobic digestion, but their removal was less extensive than expected based on previous laboratory studies. Removal for intI1 during anaerobic digestion equaled 0.28 ± 0.03 log 10 units (mean ± SE), equivalent to only 48% removal and notable given intI1's role in horizontal gene transfer and multiple resistance. Furthermore, tet(W) concentrations were unchanged during anaerobic digestion (p > 0.05), and erm(B) concentrations increased by 0.52 ± 0.03 log 10 units (3.3-fold), which is important given erythromycin's status as a critically important antibiotic for human medicine. Seasonal log 10 changes in intI1, sul1, and tet(A) concentrations were ≥50% of corresponding log 10 removals by anaerobic digestion, and variation in ARG and intI1 concentrations among digesters was quantitatively comparable to anaerobic digestion effects. These results suggest that mesophilic anaerobic digestion may be limited as an intervention for ARGs in livestock manure and emphasize the need for multiple farm-level interventions to attenuate antibiotic resistance.

Microbial source tracking and land use associations for antibiotic resistance genes in private wells influenced by human and livestock fecal sources

“…It is unclear whether manure or wastewater is a more significant source of ARGs. Antibiotic use is difficult to quantify in livestock populations (Van Boeckel et al., 2015), and concentrations of ARGs range by orders of magnitude in both manure and wastewater (Ashbolt et al., 2018; Burch, Firnstahl, et al., 2022). In addition to manure's variability on the landscape, low statistical power may also contribute to the lack of significance in multivariable models, especially as two agricultural risk factors were excluded due to limiting sample size.…”

“…For the current study, qPCR analyses were conducted to quantify the integrase gene of class 1 integrons ( intI1 ) and five ARGs: erm (B), sul1 , tet (A), tet (W), and tet (X). All six targets are found in dairy manure as well as human wastewater and/or sewage (Ashbolt et al., 2018; Burch, Firnstahl, et al., 2022; McKinney et al., 2018). The ARGs collectively represent three classes of antibiotics (macrolides, sulfonamides, and tetracyclines) (Keenum et al., 2022), and the tetracycline resistance genes represent each of three distinct resistance mechanisms: an efflux pump ( tet (A)), a ribosomal protection protein ( tet (W)), and enzymatic modification ( tet (X)) (Roberts & Schwarz, 2016).…”

Pesquisa De Genes De Resistência a Tetraciclinas Em Escherichia Coli Isoladas De Sistema De Biodigestão Anaeróbica

“…As tetraciclinas são antimicrobianos de amplo uso na pecuária leiteira e saúde humana (BURCH et al 2021;ANDERSON, et al 2023). O uso excessivo de antimicrobianos em animais de produção resulta no desenvolvido de resistência a antimicrobianos em patógenos (ISKANDAR et al, 2020).…”

The Antibiotics Degradation and Its Mechanisms during the Livestock Manure Anaerobic Digestion

“…Globally, the livestock business utilizes around 60,000 tons of antibiotics per year, such for basic veterinarian care, prophylaxis, and growth promotion is a significant contributor of ARGs to the environment [ 40 ]. Various waste treatment processes are being researched to minimize ARGs in livestock manure before land application.…”